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| June 24 (Wednesday) | |
|---|---|
| 18:30-20:30 | Registration & Welcome Reception (Venue: Suntec City Guild House) |
| Address: 3 Temasek Boulevard (Tower 5)
#02- 401/402 Suntec City Mall Singapore 038983 Click here for a map with some public transport directions, or here for the official website of the Suntec Guild House | |
Keynote Lectures
Biosynthetic PLA-related polymers improved by the metabolic engineering and enzyme engineering
Division of Biotechnology and macromolecular Chemistry,
Graduate School of Engineering -
Hokkaido Univeristy, Japan
Email: staguchi@eng.hokudai.ac.jp
From the viewpoint of realizing the environmentally eco-friendly society, biologically synthesized polyhydroxyalkanoates (PHAs) are attractive materials as bio-based alternatives to petroleum-derived thermoplastics. We developed a microbial platform carrying engineered PHA synthetic enzymes that confer high enantio-selectivity and broad substrate specificity toward monomeric constituents. The finding of an engineered PHA synthase with lactate (LA)-polymerizing activity (Lactate Polymerizing Enzyme, LPE) was a major breakthrough to achieve the microbial production of unusual polymers, particularly LA-based polymers. Poly(lactic acid) (PLA) is most widespread bio-based polymer because of its superior transparency and processability. Unlike the most of current chemical processes for PLA production including the LA fermentation and chemical polymerization of LA, our microbial processes produce LA-based polymers from renewable resources via one pot fermentation. In addition, the enzymatic polymer synthesis under mild conditions allowed us to obtain extremely high enantio-pure polymers (nearly 100% ee). We have also synthesized copolymers containing the other monomers with varied side-chain lengths of 3-hydroxyalkanoates (3HAs) using an evolved LPE.
In this talk, topics for the engineering approaches to synthesize new biopolymers will be introduced. Especially, combination of metabolic engineering and enzyme engineering are very powerful toolboxes. Recently, using liquid chromatography mass spectroscopy, we established the quantitative metabolite analysis procedure to address the rate-limiting step for synthesis of LA-based polymers. This new analytical system actually provided us with improved production of PLA-related polymers. This strategy should be applicable to a wide range of PHA-producing systems. It should be also noted that the unusual substrate specificity of LPE was found to be applicable to the synthesis of PLA-related polymers incorporating even other 2-hydroxyalkanoate (2HA) monomers; glycolate and 2-hydroxybutyrate. This finding further expands the structural diversity in microbial polyesters. Xylose utilization was also an effective for production of PLA-related polymers with respect to realizing the value chain system from raw biomass to value-added biomaterials.
Strategies for Implementing (Multi)functionality in Polymer-based Materials
Institute of Biomaterial Science, Helmholtz-Zentrum Geesthacht, Teltow, Germany
Institute of Chemistry, University of Potsdam, Potsdam, Germany
E-mail: andreas.lendlein@hzg.de
The successful usage of polymeric materials strongly depends on their ability to fulfill the specific and complex demands of applications. Scientific challenges originate from the need to tailor properties as well as to combine almost independent functions in one material system. In this presentation strategies are introduced to create bio-based polymer systems, in which different material properties and functions can be adjusted by only small variations in their chemical composition. Polymer network architectures allow modular approaches for the creation of multifunctional polymers on the molecular level. Three dimensional structures of shaped bodies, such as foams or multimaterial systems, offer additional options to implement further functions associated to different hierarchical organization levels. These principles are illustrated by examples such as gelatine-based 3D architectured hydrogels, active multimaterial systems with defined internal phase geometries or multiphase copolymer networks. Besides structural functions different shape-memory capabilities, degradability and biofunctionality are considered. Potential applications are discussed ranging from actuators to biomaterial based regenerative therapies and implants for minimally invasive surgery.
Current development of biobased polymers: Focusing on high-performance polylactides
Department of Biobased Materials Science, Kyoto Institute of Technology Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan
E-mail: ykimura@kit.ac.jp
Bio-synthesis of a number of key monomers (platform chemicals) such as succinic and itaconic acids has been progressing quite rapidly. Even terephthalic and adipic acids may possibly be replaced by the ones synthesized from biomass feedstock. Until now, not a few polymers have been synthesized from these bio-based monomers and chemicals. However, their application has been limited until now, mainly because of their lower cost-performance and inferior properties compared with the oil-based polymers. In particular, for replacing structural materials made of oil-based polymers, development of high-performance bio-based polymers having toughness and durability is required. We have recently shown that polylactides (PLA) consisting of controlled stereo-sequences of L- and D-lactates provide heat-resistant materials that are characterized by the high melting temperature (Tm) of 220-230 ºC, i.e., 50 ºC higher than that of PLLA. A typical example is the stereocomplex-type PLA (sc-PLA) formed in a mixture of poly(L-lactide) (PLLA) and its enantiomer poly(D-lactide) (PDLA). Another example is the stereoblock-type PLA (sb-PLA) consisting of PLLA and PDLA block sequences. In the former case the stereocomplex (sc) crystallization is likely accompanied by homo-chiral (hc) crystallization of PLLA and PDLA homopolymers, whereas the preferential sc crystallization can readily be performed in the latter case. In the 1st SSP process, a mixture of PLLA and PDLA having medium molecular weights is subjected to solid-state polycondensation (SSP). In the 2nd two-step ROP, the polymer prepared by the first polymerization of L- or D-lactide is subjected to the subsequent polymerization of the other enantiomeric lactide. In the 3rd polymer coupling route, PLLA and PDLA having anthracene and maleimide terminals are prepared and subjected to terminal Diels-Alder reaction. The sb-PLA polymers thus prepared can be utilized as the high-performance bio-based materials that retain sustainability. The development of biobased polymers as sb-PLAs ought to provide a new paradigm of polymer science and engineering.
Thermo-sensitive Hydrogel as Cell Carrier for Nucleus Pulposus Regeneration on Early Treatment of IVD Degeneration
Director,Institute of Biomed Eng & Nano-med, National Health Research Institutes, Taiwan
Tenure Distinguished Professor,Institute of Biomedical Engineering, National Taiwan University, Taipei, Taiwan
e-mail: double@ntu.edu.tw
Intervertebral disc degeneration usually starts at the nucleus pulposus. In the past decades, several techniques and prosthetics (artificial disc) have been developed to regenerate or replace the nucleus pulposus. However, these kind of pre-formed devices have to remove the nucleus pulposus and then replace an artificial one to relief the symptom of intervertebral disc degeneration. Recently, cell-based tissue engineering provides a rational approach to regenerate active nucleus pulposus cells (NP cells) to restore intervertebral disc architecture and function. However, the source of autologous nucleus pulposus cells are limited and their functional state does not favor regeneration. Besides, nucleus pulposus cells grown in monolayer may result in fibroblast-like transformation. Thus, the 3D hydrogel co-culture system maybe an alternative method to provide an adequate environment for nucleus pulposus cells proliferation, extracellular matrix production, cytokines secretion. In this study, we demonstrated that cell proliferation, total DNA and sulfated glycosaminoglycans synthesis of nucleus pulposus cells were significantly increased in the 3D hydrogel co-culture system. Furthermore, the extracellular matrix related gene expression and anabolism-related gene expression in 3D hydrogel co-culture system were significantly higher than other culture condition (such as monolayer culture or cultured in 3-D hydrogel without mesenchymal stem cells regulation).The gene expression of TIMP-1 and MMP-3 decreased in 3D hydrogel with mesenchymal stem cells co-culture system. This study suggests that the thermo-sensitive hyrogel could be an adequate material for nucleus pulposus cells proliferation and extracellular matrix production. Moreover, mesenchymal stem cells could regulate the isolated nucleus pulposus cells back to normal state through paracrine communications in the developed 3-D co-culture system.
Nanobiomaterials
Dept. of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong
Email: memwang@hku.hk
The era of modern biomaterials began in the middle of the last century when major efforts were started on developing new materials specifically for biomedical applications. In recent years, nanoscience and nanotechnology have advanced rapidly and are making an enormous impact in the biomedical field. Using various nanotechnologies, nanobiomaterials are developed mainly along two directions: (1) nano-structured biomaterials, and (2) biomaterials of nano-sizes or nano-feature(s). Nano-structured biomaterials can provide desired properties which are not attainable with conventional, micro-structured biomaterials. On the other hand, biomaterials of nano-sizes or nano-feature(s) can affect/direct cellular and tissue responses. Nano- or micro-sized biomaterials can be used as drug, biomolecule or gene carriers for the targeted delivery and controlled and sustained release. Nanomedicine emerged a decade ago and involves using nanotechnologies to detect and treat diseases. For example, nanoparticles (polymer-, metal- or ceramic-based) have attracted great attention for their potential as diagnostic and/or therapeutic tools in oncology. A major direction in cancer nanotechnology is the design and development of multifunctional nanodevices, the so-called “theranostics”. Tissue engineering has made great advances over the past two decades and simple tissues such as skin or bone can now be successfully regenerated in the body. Researchers are now poised to tackle difficult problems such as the regeneration of complex human body tissues. Nanobiomaterials, nanomedicine and tissue engineering are high-impact developments in the engineering and medical fields from which huge benefits can be gained for both patients and the healthcare system. For more than 10 years now, we have been conducting research on nanoparticles, nanofibers and nanocomposites for biomedical applications, including theranostics and tissue regeneration. The nanoparticles, polymeric, metallic, ceramic or hybrid, are synthesized in different ways. Nanofibers are produced via electrospinning and used for tissue engineering or controlled release applications. We have investigated various techniques, including 3D printing, for fabricating nanocomposite tissue engineering scaffolds. Stem cells have been used for studying both cell-scaffold interactions and targeted cell differentiation as well as for evaluating the scaffolds. This presentation will give an overview of our research in nanobiomaterials and their applications in nanomedicine and tissue engineering. Some critical issues are discussed in the design and development of nanobiomaterials.
From Fundamentals to Applications: Biopolymer Engineering for Delivery of Active Molecules to the Skin, for Bone and Beyond
School of Chemical and Biomedical Engineering, Nanyang Technological University,Singapore 639457
Emails: SLim@ntu.edu.sg and TeohSH@ntu.edu.sg
INTRODUCTION: Biopolymers find applications in various fields raging from industrial and environment to medicine. In this talk we will focus on the engineering of protein-based and biopolymers as carriers to deliver active molecules to the skin for potential in wound healing and engineering micro architecture to trap stem cells for bone regeneration. The. protein-based material is formed by self-assembly of the subunits of pyruvate dehydrogenase multi-enzyme complex into hollow caged structure and is referred to as protein nanocage (PNC). The biopolymer polycaprolactone (PCL) has demonstrated implant applications in bone regeneration for more that a decade. Future incorporation of PNC into PCL membrane will expand the utility of PNC/PCL for extended release.
METHODS: The engineering of PNC interior, exterior, and inter-subunit interfaces is achieved through recombinant DNA technology. The cell penetrating ability of the engineered PNC was examined in vitro on keratinocyte cell culture and imaged using confocal microscope and flow cytometry. Applications of PCL biopolymers were carried out via 3D printing technology and bi-axial stretching.
RESULTS: The interior of the PNC is engineered to allow attachment of active ingredients while the exterior is decorated with skin penetrating and cell entering (SPACE) peptides. pH-responsive property for the release of active molecules from the interior has been achieved by modifying the inter-subunit interfaces of the PNC with the amino acid histidines. SPACE-decorated PNC shows enhanced cellular penetration.
DISCUSSION: Engineering of the carrier to deliver active molecules to the skin for wound healing application requires meticulous design. In this study we have shown that PNC can be engineered for encapsulation of active molecules with triggered release property. Cellular penetration is enhanced by decorating the PNC with SPACE peptides. Incorporation of the engineered PNC together with factors important in wound healing into PCL membrane will expand the utility of the biopolymer applications
Designing for end-of-life of Biobased Polymers - Understanding the Science and Role of Biodegradability and Recyclability in Material Design.
Department of Chemical Engineering & Materials Science, Michigan State University
Email: narayan@msu.edu
Biobased polymer materials/plastics offers the value proposition of removing carbon dioxide from the environment and embodying it into the polymer molecule via plant photosynthesis at a rate and time scale (1-10 years) that is in harmony with Nature’s biological carbon cycle. Petro/fossil carbon materials cannot be credited with any CO2 removal as they have been formed over millions of years. However, it is important that biobased materials have a clearly defined and environmentally responsible end-of-life option based on the application and end-use.
Recycling (chemical or mechanical) is a viable and important end-of-life option for non-biodegradable, durable, and recoverable products. Biobased PET bottles, PE containers, polyurethanes are exemplars – they are not biodegradable, but can be collected and recycled.
Designing for complete biodegradability in concert with a disposal system like composting (compostable plastics) and anaerobic digestion offers an environmentally responsible end-of-life for biobased polymer products. Biobased and biodegradable-compostable single use disposable packaging, particularly food packaging, disposable products and plastic ware is an "enabling technology" to divert food and other biowastes (40-50% of a country’s municipal solid waste) from landfills to environmentally responsible composting and anaerobic digestion disposal systems. Biobased and biodegradable agricultural plastics and mulch film also offer an environmentally responsible value proposition provided one can design for performance, cost and complete soil biodegradability in 1-2 year time frame.
The marine environment is NOT a disposal environment. There may be value if products that "inadvertently" enter into the marine environment are designed to be not persistent and utilized by marine microorganisms. However, they can persist over long time periods in ocean environments causing serious environmental and human health impacts.
Misleading and false biodegradability claims based on additives added into conventional polyolefin resins like polyethylene, polypropylene, and PET are proliferating in the marketplace and the scientific community needs to be proactively involved.
Updates on Bioplastic Developments in Korea: Industrial Perspective
Department of Polymer Science and Engineering, Inha University, Incheon, Korea
Korean Bioplastics Association, Korea
Email: ichin@inha.ac.kr
Research and development efforts of bioplastics in Korea has made significant achievement over the last couple of decades thanks to the government drive which strongly endorses biochemical business as one of the top-priority, new growth engines for the future Korea. However, although several chemical companies had actively engaged by investing in bioplastics, the bioplastic industry has not reached the economy of scale yet. Many bioplastic products on the market still rely on biodegradable feature; however, issues such as sustainability, renewability of resources and carbon neutrality are becoming more important. Thus, biomass-based plastics are gaining more attention by being increasingly used for semi-durable and durable applications. While Korea lacks in biomass feedstocks that are commercially available, a handful of companies and research centers have developed proprietary technologies to produce several different biomass-based monomers. In this lecture industrial development activities of representative chemical companies and research institutes in recent years will be reviewed. Status quo and future outlook of Korean bioplastic industry will be discussed in global perspective. Critical issues that need to be overcome to further grow the market will also be addressed.
Invited Lectures
Production of tailor-made Alginates by engineered Bacteria
Institute of Fundamental Sciences and MacDiarmid Institute for Advanced Materials and Nanotechnology, Massey University, Palmerston North, New Zealand
Alginates are polysaccharides composed of two building blocks, mannuronic acid and guluronic acid, and the sequence and arrangement of these monomers strongly impact their material properties. The mannuronic acid can also be acetylated. Physical properties can range from viscous solutions to self-assembling pseudoplastic materials. Its unique material properties and biocompatibility has led to uses as a viscosity regulator and stabilizer in foods, cosmetics and high-value medical applications including wound dressings, drug delivery systems and more recently in tissue encapsulation for regenerative therapy. Commercial alginates are extracted from brown algae and suffer from heterogeneity and lack purity. Increasing knowledge about bacterial alginate biosynthesis and our recent studies suggest the use of bioengineered bacteria to produce a range of defined and tailor-made alginates with desirable material properties. In this study, the membrane spanning multiprotein complex involved in alginate synthesis and modification was investigated with the aim to produced tailor-made alginates. For example, the protein-protein interactions and interactive role of membrane-anchored proteins Alg8 (polymerase) and Alg44 (co-polymerase) as well as periplasmic proteins AlgG (epimerase), AlgX (acetyltransferase) and AlgK (lipoprotein) on alginate polymerization and modification was studied by using site-specific deletion mutants, inactive variants and overproduction of subunits. The composition, molecular weight and materials properties of resulting novel alginates were analyzed. Interestingly the molecular weight was reduced by epimerization while it was increased by acetylation. Overproduction of Alg44, AlgG and the non-epimerizing variant AlgG(D324A) increased the degree of acetylation while epimerization was enhanced by AlgX and its non-acetylating variant AlgX(S269A). This study demonstrated that engineering of the alginate synthesis/modification multiprotein complex enables the production of various novel alginates.
Recovery of Polyhydroxyalkanoate from Bacterial Cells: Is there an Easier Way?
School of Biological Sciences, Universiti Sains Malaysia, Malaysia
Email: ksudesh@usm.my
INTRODUCTION: Polyhydroxyalkanoate (PHA) is a bacterial storage polyester accumulated as water insoluble granules in the cell cytoplasm. PHA has been researched extensively for its potential application as biodegradable plastics. The cost of PHA is currently high compared to similar polymers in the market, which hinders successful commercialization. Recovery and purification of PHA from bacterial cells are among the costly processes involved in the production of PHA.
METHODS: Cupriavidus necator cells were cultivated in mineral medium with palm oil or used cooking oil as the carbon source. The cells were harvested after 48-72 hours and freeze-dried. Dried cells containing poly(3-hydroxybutyrate) [P(3HB)] and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) [P(3HB-co-3HHx) granules were fed to animal models. The resulting fecal matter was collected and subjected to GC, GPC, DSC, TGA, rheology and protein analyses. Fecal matter was also subjected to further mild washing treatments with detergents.
RESULTS: The animal models used in this study readily consumed the freeze-dried C. necator cells that contained PHA granules and produced whitish fecal pellets. GC analysis of the fecal pellets revealed that they contained PHA of up to more than 90 wt%. Further washing treatments with detergents resulted in more than 95 wt% PHA. DSC, GPC and TGA analyses showed that the PHA granules recovered using this method had similar characteristics to the PHA obtained by chloroform extraction. However, the rheological properties of the PHA obtained from both these methods demonstrated clear difference. Proteins were detected in the biologically extracted PHA granules, which may be the reason for the observed differences in rheological properties.
DISCUSSION: The biological extraction method reported here is simple, scalable and can be integrated into some existing animal production systems. The resulting PHA may be suitable for some agricultural applications such as in the development of slow release fertilizer systems.
Production of lactic acid using thermophilic bacteria from lignocellulose
Institute of Chemical and Engineering Sciences, A*SATR, 1 Pesek Road, Jurong Island, Singapore 627833
Email: wu_jinchuan@ices.a-star.edu.sg
INTRODUCTION: The demand for optically pure lactic acid is increasing owing to the rapid growth of poly lactic acid (PLA) industry. Lactic acid is currently produced by microbial fermentation from starchy materials. To avoid the competition with the supply of foods and feeds, it is essential to produce lactic acid from lignocellulose, the most abundant renewable resource on earth.
METHODS: Oil palm empty fruit bunch (EFB) was hydrolyzed to get hemicellulose sugars by the combined use of dilute H2SO4 and H3PO4 in a 2-step process without any additional concentration steps, giving >110 g/L of total sugars in the hydrolysate. Furfural, 5-hydroxymethyl furfural and acetic acid in hydrolysate were sequentially degraded by simply adding the whole cells of the bacteria that were isolated from nature. Thermophilic Bacillus coagulans strains were isolated from the natural environment and used to convert all lignocellulose sugars to L-lactic acid at 50°C without the requirement of sterilizing the medium before fermentation.
DISCUSSION: In a simultaneous detoxification, saccharification and co-fermentation process, 80.6 g/L of L-lactic acid was obtained at a productivity of 3.4 g/L/h from total EFB including both hemicellulosic and cellulosic fractions. A 1-pot, 1-step process for simultaneous saccharification and fermentation (SSF) was developed to convert starch to L-lactic acid at 50°C under non-sterilized condition, giving 202 g/L of L-lactic acid from 200 g/L of corn starch. To reduce the nitrogen source cost for fermentation, expensive yeast extract was replaced with the same amount of cheap dry yeast achieving almost the same lactic acid titer, productivity and yield. Ca(OH)2 was found to be a better neutralizing agent to control the pH during fermentation than NaOH and NH4OH in terms of the higher lactic acid titer and productivity.
Amphiphilic Peptides That Mimic Nature – A versatile platform for combining and controlling biofunctional signaling, mechanical strength and chemical degradation
Dept of Chemical and Biomolecular Engineering ,National University of Singapore
The self-assembling behavior of peptide amphiphiles has been studied for over 20 years, and has been found to have interesting behaviors and applications. Recently, our group has worked on using these peptide amphiphiles to mimic nature in a multi-scale manner, from molecular signaling through receptor interactions, to hierarchical assembly that changes nanofibers into micro- and macro-fibers, and at the physiological level in controlling mechanical strength. The eventual goal is to mimic nature to produce synthetic materials that behaves like extracellular matrices with its corresponding biological, mechanical and chemical behavior and function. The peptide amphiphiles are more than a versatile platform, as it is also surprisingly simple to design a range of these functions through logical peptide selection and by learning from nature. We have achieved mimicry of ECM molecules from collagen to elastin, and from spider to silkworm silk. Our applications are currently aimed at tissue engineering of soft tissues such as liver and brain, to hard tissues of bone, and elastic tissues of the skin and fat.
Amino Acids Make 3HB-Based PHA Copolymers More Diverse
Tokyo Institute of Technology, Japan
Email: tsuge.t.aa@m.titech.ac.jp
Nowadays, over 150 different building blocks are known for polyhydroxyalkanoate (PHA). Poly[(R)-3-hydroxybutyrate], P(3HB), is the most common type of PHA but P(3HB) is brittle and has poor flexibility due to high crystallinity. Therefore, 3HB-based copolymers are now recognized as a practical material.
P(3HB-co-3-hydroxyvalerate), P(3HB-co-3HV), is the first developed copolymer; however, 3HB and 3HV are co-crystallized each other, thus, P(3HB-co-3HV) still has low flexibility. P(3HB-co-3-hydroxyhexanoate), P(3HB-co-3HHx), has more flexible than P(3HB-co-3HV), and has attracted a great deal of industrial attention in recent times.
Other than linear side-chain monomer units, amino acids can potentially provide diverse side-chain monomers such as branched side-chain and aromatic side-chain. For example, leucine and valine can provide 3-hydroxy-4-methylvalerate (3H4MV) unit, which has branched side-chain. Phenylalanine is also potential precursor for 3-hydroxy-3-phenylpropionate (3H3PhP) unit, which has phenyl side-chain.
These 3HB-based copolymers, P(3HB-co-3H4MV) and P(3HB-co-3H3PhP), exhibit better material properties than conventional P(3HB) and P(3HB-co-3HV). Additionally, almost of all PHA-producing bacteria possess complete amino acid biosynthesis pathways, thus, it would be possible to conduct metabolic engineering of amino acid biosynthesis pathway for supplying such amino acid-derived monomers. This presentation will cover mainly resent advantages in amino acid-derived PHA synthesis.
Effect of the electrospinning conditions on the higher-order structure and the stereocomplex formation of the PLLA/PDLA blend nanofibers
1*Dept. of Bio-based Materials Science, Graduate School of Science and Technology, Kyoto Institute of Technology, Kyoto 606-8585, JAPAN.
2Dept. of Mechanical Engineering, University of Malaya, 50603 Kuala Lumpur, MALAYSIA
Email: hyamane@kit.ac.jp
Nowadays, over 150 different building blocks are known for polyhydroxyalkanoate (PHA). Poly[(R)-3-hydroxybutyrate], P(3HB), is the most common type of PHA but P(3HB) is brittle and has poor flexibility due to high crystallinity. Therefore, 3HB-based copolymers are now recognized as a practical material.
P(3HB-co-3-hydroxyvalerate), P(3HB-co-3HV), is the first developed copolymer; however, 3HB and 3HV are co-crystallized each other, thus, P(3HB-co-3HV) still has low flexibility. P(3HB-co-3-hydroxyhexanoate), P(3HB-co-3HHx), has more flexible than P(3HB-co-3HV), and has attracted a great deal of industrial attention in recent times.
Other than linear side-chain monomer units, amino acids can potentially provide diverse side-chain monomers such as branched side-chain and aromatic side-chain. For example, leucine and valine can provide 3-hydroxy-4-methylvalerate (3H4MV) unit, which has branched side-chain. Phenylalanine is also potential precursor for 3-hydroxy-3-phenylpropionate (3H3PhP) unit, which has phenyl side-chain.
These 3HB-based copolymers, P(3HB-co-3H4MV) and P(3HB-co-3H3PhP), exhibit better material properties than conventional P(3HB) and P(3HB-co-3HV). Additionally, almost of all PHA-producing bacteria possess complete amino acid biosynthesis pathways, thus, it would be possible to conduct metabolic engineering of amino acid biosynthesis pathway for supplying such amino acid-derived monomers. This presentation will cover mainly resent advantages in amino acid-derived PHA synthesis.
Preparation of Novel Sustainable Polymers from Resin Acids and Plant Oils
Department of Chemistry & Biochemistry, University of South Carolina, Columbia, SC 29208, USA
Email: tang4@sc.edu
Sustainable chemicals and materials from renewable natural resources have a great potential in replacing petroleum-derived counterparts. Research in this field is becoming one of the cornerstones in polymer science for next generations and beyond. Natural molecular biomass plays an important role in the field of renewable polymers, as they can be directly used or derivatized as monomers for polymerization, in a way similar to many petroleum-derived monomers. This presentation will be focused on the synthesis of renewable polymers from a class of hydrocarbon-rich biomass by controlling macromolecular architectures for desirable applications. I will discuss the preparation of renewable thermoplastics and thermoplastic elastomers derived from natural resin acids (rosin), fatty acids and plant oils. I will also talk about how to utilize the unique structure and function of natural hydrophobic moiety for the development of novel antimicrobial biomaterials against a wide spectrum of bacteria including superbugs.
References
- Yao K.; Tang C. Controlled Polymerization of Next-Generation Renewable Monomers and Beyond. Macromolecules, 2013, 46, 1689-1712
- Jiang F.; Wang Z.; Qiao Y.; Wang Z. G.; Tang C. A Novel Architecture toward 3rd-Generation Thermoplastic Elastomers by a Grafting Strategy, Macromolecules, 2013, 46, 4772-4780.
- Ganewatta M. S.; Chen Y.-P.; Wang J.; Zhou J.; Ebalunde J.; Nagarkatti M.; Decho A. W.; Tang C. Bio-inspired Resin Acid-Derived Materials as Anti-Bacterial Resistance Agents with Unexpected Activities. Chem. Sci., 2014, 5, 2011 - 2016.
Controlled/Living Polymerization of Renewable Vinyl Monomers into Novel Bio-Based Polymers
Department of Applied Chemistry, Graduate School of Engineering, Nagoya University, Nagoya, Japan
Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency (JST), Japan
Email: satoh@apchem.nagoya-u.ac.jp
In this talk, the author will present the overview of our recent research topic in bio-based polymers by the controlled/living polymerization of naturally-occurring or -derived renewable monomers, such as terpenes, phenylpropanoids, and itaconic derivatives. The judicious choice of initiating system, which was borrowed from conventional petrochemical monomers, allowed not only the polymerization to proceed well but also afforded well-defined controlled/living polymers from these renewable monomers. We were able to find several controlled/living systems for the renewable monomers, which resulted in novel bio-based polymers including cycloolefin polymer, AAB alternating copolymer with an end-to-end sequence, phenolic and high-Tg alternating styrenic copolymer, and acrylic thermoplastic elastomer. For example, beta-pinene was cationically polymerized as alicyclic hydrocarbon monomers in a controlled fashion to result in a promising novel bio-based cycloolefin polymer. The beta-pinene or limonene underwent unprecedented 1:2 alternating radical copolymerization with maleimide derivatives, and the combination with a reversible addition-fragmentation chain transfer (RAFT) agent for the controlled/living radical polymerization resulted in end-to-end sequence-regulated copolymers with both highly-sequenced chain ends and main-chain repeating units as well as controlled molecular weights.
Chemo-enzymatic modification of microbial polyesters PHAs: preparation of thermoplastic or shape-memory block co-polymers
Department of Chemical & Biomolecular Engineering National University of Singapore, 4 Engineering Drive 4, Singapore 117585
Poly-[(R)-3-hydroxyalkanoates] (PHAs) are biodegradable and biocompatible materials produced by microorganisms. While these biopolyesters can be used directly for many applications, PHAs oligomers are excellent segments for engineering block co-polymers with desired material properties. We recently developed new concepts and methods for the preparation of PHAs-based block co-polymers with good thermoplastic or shape-memory properties for biomedical applications via chemo-enzymatic setting of PHAs oligomers. In this presentation, the following topics will be addressed: a) development of a green method for the preparation of thermoplastic block co-polyesters containing poly[(R)-3-hydroxybutyrate] (PHB) and poly[(R)-3-hydroxyoctanoate] (PHO) blocks via enzyme-catalysed polycondensation of telechelic PHB-diol and PHO-diol with divinyl Adipate; b) development of a new synthetic method for the preparation of thermoplastic di-block co-polyesters containing PHB and poly(ε -caprolactone) (PCL) blocks via enzyme-catalysed ring-opening polymerization of ε-caprolactone with PHB-diol; c) preparation of novel thermoplastic di-block co-(polyester-carbonate) containing PHB and poly(trimethylene carbonate) blocks via enzyme-catalyzed ring-opening polymerization of trimethylene carbonate with PHB-diol; and d) synthesis and characterization of novel biodegradable shape-memory block co-polymers containing PHBV hard block and hyperbrached MDI-linked PCL switching block as fast self-expandable stents.
Synthesis and Characterization of Biobased Copolyester Containing Biomass Monomer
Department of Nano and Organic engineering, Faculty of Engineering, Hanyang University, Seoul, Korea
Abtsrcat not available online.
Syntheses and Structure of Copolymers with Alternating Sequences of 3-Hydroxybutyrate and Lactate Units
Bioplastic Research Team, RIKEN Center for Sustainable Resource Science, Japan
Email: habe@riken.jp
We focused the structure and physical properties of alternating copolymers consisting of α-hydroxyl acid monomeric unit of lactate (2-hydroxypropionate: 2HP) and β-hydroxyl acid monomer unit of (R)-3-hydroxybutyrate ((R)-3HB). Taking into account the chiral structure of monomeric units, two types of stereoisomeric dimers ((R)-3HB-(R)-2HP and (R)-3HB-(S)-2HP) were respectively prepared, and the alternating copolymers with different stereocompositions were synthesized from the dimeric monomers by condensation reaction. Based on the NMR analyses, it was confirmed that the obtained copolymers had an alternating sequence of (R)-3HB and 2HP units. In contrast to random copolymers of (R)-3HB and 2HP units, the repeating sequence of alternately connected (R)-3HB and 2HP units formed crystalline region. The copolymer with alternating sequence of (R)-3HB and (S)-2HP units had a melting temperature at 83 °C. On the other hands, the melting temperature of copolymer of (R)-3HB and (R)-2HP units was quite higher than those of the corresponding homopolymers (around 180 °C) and reached to 233 °C. When the alternating copolymers were prepared from a mixture of stereoisomeric dimers, both the melting temperature and crystallinity varied in the wide ranges depending on the composition of stereoisomeric dimmers. In addition, the crystalline structure of alternating copolymers was characterized from the X-ray and electron diffraction patterns of lamellar singe crystals. The relationship between the crystalline structure and thermal properties in the alternating copolymers were discussed.
Dynamic Covalent Polymers from Bio-based Furan
Institute of Industrial Science, The University of Tokyo, Komaba, Tokyo 153-8505, Japan
E-mail:yoshie@iis.u-tokyo.ac.jp
A bio-based polyester, poly(2,5-furandimethylene succinate) [PFS], was prepared from bis(hydroxymethyl)furan and succinic acid, both of which are obtainable from biomass. This polyester possesses many furan rings in the main chain, allowing the formation of reversible cross-links by the Diels-Alder reactions with bis-maleimido [M2]. By controlling the amount of M2, the networked furan polymers, PFS/M, with a wide variety of properties were obtained. They include relatively hard materials with a yield point and flexible elastic ones. Among the networked furan polymers, the elastic ones had good self-healing ability: when it broke, their surfaces could be rejoined without any external stimulus at room temperature. Healing was more effective when the broken surfaces were activated by a solvent (chloroform) or by an M2 solution. For example, PFS/M2 with furan-to-maleimide ratio of 6/1 recovered as much as 74% of the toughness of the original sample by self-healing and over 90% of the toughness by treatment with chloroform or 70 g l−1 M2 solution. To the best of our knowledge, this is the first report on the room temperature self-healing of furan−maleimide polymers. Further, the network polymers show unique multi-shape memory controlled by local glass transition temperature. Local glass transition temperatures of a PFS/M film were changed by immersing sections of the film in a M2 solution with a different concentration. Each section memorizes a temporary shape, which recovers its permanent shape at a different recovery temperature depending on the local glass transition temperature. The PFS/M polymer offers the possibility of materials having practical mechanical properties and unique functionalities of self-healing and shape memory.
Construction and New Applications of Biomass-based Cyclic Polylactones
Institute of Chemical and Engineering Sciences, 1, Pesek Road, Jurong Island, Singapore 627833
Email: zhu_yinghuai@ices.a-star.edu.sg
Biodegradable polymers produced from renewable resources such as lactones, attract growing interest and become more important both in academia and industry. These materials have high potential to replace the existing fossil oil-based materials in many areas such as in packaging and agriculture due to the depletion of fossil oil in future [1,2]. In our lab, we are developing biodegradable materials in synthetic methodology and looking for new applications of cyclic polylactones [3,4]. Cyclic polymers have unique properties and inherent advantages such as low melting viscosity, controllable Mw and rapid crystallization when compared with long-chain-based linear polymer architectures [5]. Therefore, the cyclic polymers are expected to find specific applications in microelectronics, textiles, biomedical and pharmaceutical industries, as well as catalysis. In the presentation, we report the preliminary results regarding synthesis and application as catalyst support of cyclic polylactone-clay hybrid. The hybrid has been prepared by a zwitterionic ring opening polymerization catalyzed by in situ generated N-heterocyclic carbenes. The resulting hybrid has been found a good support for palladium nanoparticles-based catalysts [4,6].
References
- Dechy-Cabaret, O.; Martin-Vaca, B.; Bourissou, D. Chem. Rev. 2004, 104, 6147.
- Kamber, N. E.; Jeong, W.; Waymouth, R. M.; Pratt, R. C.; Lohmeijer, B. G. G.; Hedrick, J. L. Chem. Rev. 2007, 107, 5813.
- Prasad, A. V.; Stubbs, L. P.; Ma, Z.; Zhu, Y. J. Appl. Poly. Sci. 2012, 123, 1568.
- Prasad, A. V.; Zhu, Y. J. Appl. Poly. Sci. 2013, 128, 3411.
- Y. Zhu, N. S. Hosmane, Chemistry Open, 2015 manuscript accepted.
- Y. Zhu, N. S. Hosmane, Coord. Chem. Rev. 2015, on-line.
Interfacial Polyelectrolyte Complexation Fibers for Tissue Engineering
Institute of Bioengineering and Nanotechnology, 31 Biopolis Way, The Nanos, Singapore 138669
Chitin, the second most abundant natural polymer after cellulose and a constituent of shellfish exoskeleton, and alginic acid, a well-studied biopolymer commonly derived from seaweed, form the basis of a fiber type that our laboratory has extensively investigated for biomedical application. Interfacial polyelectrolyte complexation (IPC) fibers are drawn from the interface of two oppositely charged polyelectrolytes. Being a mild, aqueous-based process, IPC is amenable towards the encapsulation of cells at near-neutral pH solutions, providing a 3D matrix that is permissible to both cells and the factors that support their viability and function. We have used IPC fibers for stem cell expansion and differentiation, to create pre-vascularized constructs for tissue engineering, and to set up 3D in vitro models for drug screening. While our earlier efforts were based on the use of non-woven scaffolds, we have since developed multicomponent fibers and fiber-assembly processes that allow us to spatially pattern biological components in three dimensions, to recapitulate cell-cell and cell-ECM interactions that are necessary in the tissue engineering endeavor.
Uses of Agricultural Waste Product, Silk Sericin, in Medical Applications
Department of Pharmacy Practice, Faculty of Pharmaceutical Sciences, Chulalongkorn University, Bangkok, Thailand
Silk derived from the silkworm Bombyx mori is composed of two major protein components, fibroin and sericin. Fibroin is a fibrous protein, presented as a delicate twin thread linked by disulfide bonds, enveloped by sericin with successive sticky layers that help in the formation of a cocoon. Sericin or silk glue constitutes 25–30% of silk protein. It contains 18 amino acids, most of which have strong polar side chains as hydroxyl, carboxyl and amino groups made it easily soluble in water. Sericin has been studied for various potential applications because of its unique biochemical and biophysical properties, including biocompatibility, biodegradability, antibacterial, antioxidant, anti-tyrosinase, anticancer, UV light protecting activity, coagulant and moisturising.
We have found that sericin can activate collagen production from fibroblast cells. Due to that property, sericin has been widely investigated for its use as wound healing material. The results from clinical study showed that silk sericin scaffold and silk sericin cream can significantly promote partial-thickness wound healing compared to commercial, standard wound dressing. Since sericin can suppress interleukin and tumor necrosis factor production, it show not only benefit in wound care, but applying sericin cream can also reduce the itching intensity of the skin in hemodialysis patients and can be used as a treatment choice for psoriasis. The mechanism of action of sericin in reducing oxidative stress and COX-2 made it applicable for decreasing skin tumor incidence and tumor multiplicity from ultraviolet B damages.
Consumption of sericin also shows benefit in clinical applications. In vivo study indicated that sericin, especially low molecular weight one, can reduce colon tumorigenesis by activate apoptosis of cells. It also can reduce high blood sugar level in diabetic patients which will be useful if use as adjunct therapy. In hyperlipidemia rats, sericin can significantly reduce low density lipoprotein and triglyceride levels while increase serum high density lipoprotein level.
From agricultural waste, broad applications of sericin were found both in cosmetic and medical uses. Further investigation, especially in clinical study, needs to perform in order to determine the dose and confirm the results. Use of sericin not only provide a new choice of medical material, but also reduce the pollution causes from discarding this waste into the nature.
Water-based Chitosan for Bio-sensors and Detection Systems
1The Petroleum and Petrochemical College, Chulalongkorn University
2Department of Anatomy, Faculty of Medicine, Chulalongkorn University
3Department of Microbiology, Faculty of Medicine, Chulalongkorn University
4Center for Petroleum, Petrochemical, and Advanced Materials, Chulalongkorn University, Bangkok 10330, Thailand.
Email: csuwabun@chula.ac.th
INTRODUCTION: Chitosan is known as the only natural occurring polysaccharide with the reactive functional groups, i.e. hydroxyl and amine groups, to lead to the bio-related properties, cationic properties and the various derivatizations. However, the fact that chitosan has the strong inter- and intramolecular hydrogen bonds, it is insoluble in most solvents except carboxylic acids. Thus, most chemical modifications of chitosan are rather complicated with multi steps in harsh conditions and required the many organic solvents. The uses of chitosan in biomedical field, though it is the way for the advanced and value-added applications, did not get much attention as it should be. The present work focuses on a simple chitosan conjugating reaction in water to propose the water-based sensors and detection systems for biomolecules.
METHODS: Chitosan water soluble was prepared by simply mixing with hydroxybenzyltriazole (HOBt) or N-hydroxylsuccinimide (NHS) in equimolar. The conjugating reaction was further carried out at room temperature with carboxyl group containing molecules, i.e. oxanorbonadiene, poly(N-isopropyl) acryamide (PNIPAM), thymine, and protein (antibody). For chitosan-antibody, chitosan was coupled with magnetic nanoparticles using silane coupling agent in prior step. Each product was dialyzed and the functions as the bio-sensors or the bio-detections were investigated.
RESULTS AND DISCUSSIONS: Chitosan-oxanorbonadiene rapidly changes the pink color of azido-gold nanoparticles to violet as a consequence of copper free Click and this can be used as antigen detection system. Chitosan-PNIPAM entraps and releases magnetic nanoparticles (MNPs) by simply changing the temperature at its LCTS (~37 °C). This enables the release of MNPs out of the species in need after finishing the use of MNPs in the extraction process. Chitosan-thymine shows the strong interaction with poly(A), DNA, and RNA as identified from electrophoresis technique. This implies the potential application of the simple gene identification.
All-celulose Composites and Nanocomposites
Dept. Chem. Sci. & Eng.,
Graduate School of Engineering
Kobe University, Japan
Email: tnishino@kobe-u.ac.jp
Composite materials, typically glass fibers or carbon fibers embedded into epoxy resin or unsaturated polyester, show excellent mechanical and thermal properties; thus, they are widely used in various applications ranging from aerospace to vehicles to sports utensils. However, these advantages cause environmental problems when disposing by incineration. Consequently, there are growing demands for environmentally friendly composites. Paradigm shift from energy consuming materials to sustainable materials has brought increasing importance of biomass utilization. Biofibers are among the most keenly required materials of the twenty-first century.
In general, composites are composed of two chemically different materials. The interface between the incorporated fiber and the matrix often causes problems, such as poor compatibility, insufficient stress transfer, and high water uptake. If the fiber and the matrix are both made of the same material, benefits such as recyclability and good adhesion through the perfect interface can be expected. A recent emerging concept of all-cellulose composites, where the reinforcement and matrix are both cellulose, has received increased attention.
The average strength of 480 MPa for the all-cellulose composite was comparable or even higher than that of conventional glass-fiber-reinforced composites. In addition, modulus is comparable with that of Mg alloy, frequently used as light weight alloy for electric devices. In addition, the all-cellulose composite is optically transparent, because of all composed of single component (cellulose) and interface free structure. The all-cellulose composite is totally composed of sustainable resource, biodegradable after the service, which gives it advantages with regard to disposal, composting, and incineration. It possesses excellent mechanical (high modulus / high strength), thermal (high heat resistance, low thermal expansion) and optical performance (high transparency) during use.
The procedure, structure and properties of all-cellulose composite and nanocomposite would be reviewed.
Structural and Material Design of Cellulose Paper Composites
The Institute of Scientific and Industrial Research, Osaka University, Japan
Email: hkoga@eco.sanken.osaka-u.ac.jp
INTRODUCTION: Flexible and wearable electronics has recently attracted increasing attention, because it can open up new possibilities for next-generation portable devices. Opaque or transparent paper materials, which are prepared from cellulose pulp fibers or nanofibers, respectively, have been regarded as promising substrates alternative to conventional glasses and plastics for flexible electronic devices. The unique features of the paper include renewability, biodegradability and porous structures. Here we present flexible paper electronics, such as transparent conductive paper, prepared by using paper-specific porous structures.
METHODS: For preparation of transparent conductive paper, an aqueous suspension of cellulose nanofibers was first dewatered on a membrane filter under suction filtration. Subsequently, an aqueous suspension of silver nanowires or carbon nanotubes was poured and filtered in the similar manner. The resulting wet sheet was covered with a hydrophobic glass, followed by hot pressing at 110°C for 20 min (1.1 MPa) and peeling from the membrane filter.
RESULTS: Uniform coating of silver nanowires and carbon nanotubes was achieved by simple filtration of their aqueous dispersions through the cellulose nanofiber paper, which acted as both filter and transparent flexible substrate. The as-prepared silver nanowire networks on the nanopaper offered sheet resistance of 12 Ω sq-1 with optical transparency of 88%, which was up to 75 times lower than the sheet resistance on a plasrtic film prepared by conventional coating processes.
DISCUSSION: These results indicated that the ‘filtration coating’ provides uniformly connected conductive networks because of drainage in the perpendicular direction through paper-specific nanopores, while conventional coating processes inevitably cause self-aggregation and uneven distribution of the conductive nanomaterials because of the hard-to-control drying process, as indicated by the well-known coffee-ring effect. This filtration process is expected as an effective coating approach for various conductive materials. The transparent conductive nanopaper is a promising material for future paper electronics.
Dispersion and Interaction of Graphene oxide in Poly(3-hydroxybutyrate) Nanocomposites
Department of Chemistry, Polymer & Materials Chemistry, Lund University,Lund, Sweden
Email: frans.maurer@polymat.lth.se
INTRODUCTION: The modification of physical properties of P3HB by the incorporation of small amounts of graphene oxide (GO) was explored, with the aim to widen the application range of P3HB and to modify its rheological behavior.
METHODS: Several important physical properties could be measured as a function of GO content with the following characterization techniques; SEC, X-ray diffraction, DSC, TGA, Dynamic Rheology and Positron Annihilation Lifetime Spectroscopy (PALS). The samples were prepared by solution mixing, by evaporation of the solvent and finally pressing of the dry samples during 2 min at 180°C.
RESULTS: Rheological measurements were performed as a function of time at 185oC, facilitating the determination of an equilibrium modulus characteristic for the network structure formed by the GO particles. A power law dependence of the equilibrium moduli as a function of volume fraction was observed. The decomposition temperatures determined with TGA were not affected by GO in the P3HB nano-composites. The heat of fusion and crystallinity were slightly reduced as a function of GO content. PALS gives information about the free volume hole sizes in the amorphous phase of the semicrystalline P3HB nano-composites. The hole sizes strongly increase with amount of GO, indicating that strong hydrostatic stresses on the free volume cavities exist, induced by large differences in shrinkage of GO and the polymer during preparation of the samples.
DISCUSSION: Large changes of rheological and other important physical properties are observed when adding 0.01- 5 wt% graphene oxide to P3HB. Network formation of the nano-particles is observed and can explain the peculiar rheological behavior of the nano-composites. Dispersion of GO and interaction of GO with the P3HB matrix are major factors determining the other physical properties measured.
Engineering Protein-based Nanoparticles for Delivery of Active Molecules to the Skin
School of Chemical and Biomedical Engineering, Nanyang Technological University 70 Nanyang Drive, Block N1.3, Singapore 639457
*Emails: SLim@ntu.edu.sg and TeohSH@ntu.edu.sg
INTRODUCTION: Protein-based nanoparticles are amenable to chemical and genetic modifications. In this talk we will focus on the engineering of a model protein-based nanoparticle, E2 protein, as carriers to deliver active molecules to the skin. The E2 protein is formed by self-assembly of sixty subunits of pyruvate dehydrogenase multi-enzyme complex into hollow caged structure and is referred to as protein nanocage (PNC). Some advantages of PNCs over inorganic nanoparticles are their biodegradable properties and spatial controls for ligand displays on the exterior surface of the PNCs.
METHODS: The engineering of PNC interior, exterior, and inter-subunit interfaces is achieved through recombinant DNA technology. The engineered PNCs are produced in E. coli and purified using ion exchange chromatography method. The cell penetrating ability of the engineered PNC was examined in vitro on keratinocyte cell culture. After 1 hour incubation with fluorescently-labeled un-engineered and engineered PNC, the keratinocytes are imaged using confocal microscope and the number of cells with fluorescence was quantified with flow cytometry.
RESULTS: The interior of the PNC is engineered to allow attachment of active ingredients while the exterior is decorated with skin penetrating and cell entering (SPACE) peptides. pH-responsive property for the release of active molecules from the interior has been achieved by modifying the inter-subunit interfaces of the PNC with the amino acid histidines. The flow cytometry results show 2.5 fold increase of fluorescence in keratinocytes incubated with SPACE-engineered PNC compared to those of un-engineered PNC.
DISCUSSION: Engineering of the carrier to deliver active molecules to the skin for wound healing application requires meticulous design. In this study we have shown that PNC can be engineered for encapsulation of active molecules with triggered release property. For skin application, cellular penetration is enhanced by decorating the PNC with SPACE peptides. Further studies using orthologous skin model is underway.
Novel Bio-Based Plastics for Multiple Infection Prophylaxis Possessing Versatile Coating Performance
1Agricultural Science, Graduate School of Integrated Arts and Sciences, Kochi University, Nankoku, Kochi 783-8502, Japan
2Department of Agriculture, Faculty of Agriculture, Kochi University, Nankoku, Kochi 783-8502, Japan
3 Research Center, Toyobo Co., Otsu, Shiga 520-0292, Japan
Email: ashiuchi@kochi-u.ac.jp
INTRODUCTION: Poly-γ-glutamate (PGA), a hybrid-type polymer with a nylon-like backbone and polyacrylate-like side-chain structures, has reasonable biodegradability and good biocompatibility. We recently succeeded in the plasticization of hygroscopic PGAs using a simple but effective chemical transformation1), and is hereafter called the novel bio-based plastics PGA ion-complexes (PGAICs). The first material was characterized as a stoichiometric ion-complex, containing equally the carboxyl groups of archaeal (stereo-regular) L-PGA and a compound used in toothpaste called hexadecylpyridinium (HDP+) and had the potential to serve as a functional plastic showing a broad spectrum of antimicrobial activity1), but it is still unclear whether or not the extreme hydrophilicity of PGA can be suppressed using other cationic surfactant-candidates, e.g. dodecylpyridinium (DDP), benzalkonium (BZA) and benzetonium (BZT), as well as further examinations on the functionality of PGAICs for application in hygiene technology.
METHODS: Synthesis, structural analysis, and functional assays of PGAICs were performed using the methods described previously1). Anti-influenza/cytotoxicity testing of PGAIC was conducted with the technical support of the Kitasato Research Center for Environmental Science (Japan).
RESULTS: Other PGAICs than PGA/HDP, i.e. PGA/DDP, PGA/BZA and PGA/BZT, were obtained, and we further found their spontaneous coating performance to the surfaces of different materials (plastics, metals, and ceramics) as potent anti-staphylococcal and anti-Candida agents. This study also reveals that PGAIC is a promising candidate for anti-influenza coatings.
DISCUSSION: Because PGAIC is easily transformed into a nanofiberplastic1) in addition to a safe antimicrobial dispersant for material-surface coating, it may contribute to hygienic control and infection prophylaxis in various public facilities such as schools, hospitals, and transportations, re-sulting in a decreased risk of airborne infection, contagion, and serious pneumonia, which can be lethal. Moreover, these coatings can also aid against an unforeseen epidemic of new viral infectors.
REFERENCE: 1) Ashiuchi, M.et al. ACS Appl. Mater. Interfaces 2013, 5, 1619–1624.
Characterization and Biomedical Applications of Electrospun PHA-based Fibrous Membranes
Department of Chemical Engineering and Materials Science and Graduate School of Biotechnology and Bioengineering, Yuan Ze University, Chung-Li, Taoyuan 32003, Taiwan
R&D Center for Membrane Technology, Chung Yuan University, Chung-Li 32023, Taiwan
Email: cesunym@saturn.yzu.edu.tw
Polyhydroxyalknoates (PHAs) are a class of biologically synthesized polyesters. They possess many advantageous properties such as biodegradability, biocompatibility, nontoxicity and good mechanical properties, and have received much attention in biomedical applications. In this presentation, the characterization and biomedical applications of electrospun PHA-based fibrous membranes will be discussed. In particular, the crystallization of the PHA nanofibers was found to be restricted to specific crystalline planes due to the molecular orientation along the axial direction of the fibers. The crystallization behaviors of the electrospun nanofibers were significantly different from that of the cast membranes because of the rapid solidification and the one-dimensional fiber size effect in the electrospinning process. Mechanically, the electrospun PHA nanofibrous membranes were soft but tough, and their elongation at break averaged 240-300% and could be up to 450% in some cases. The degradation rate of the fibrous membranes could be adjusted by blending with poly(D,L-lactic acid) (PDLLA). It was found that the molecular chains of PHA and PDLLA were partially mixed in the amorphous phase, PDLLA didn't affect the growth of PHA crystalline phase, and PDLLA was excluded from PHA lamella stacks, i.e. in form of interstack segregation, in the blend fibrous matrix. Although PHA is suitable for biomedical applications, it often suffers from very poor cell affinity due to its hydrophobicity and lack of functional groups for covalent bonding with biomolecules. Hence, surface modification on PHA is a critical issue to increase surface activity and bioactivities. An example of dopamine, chitosan and autologous plate-rich plasma (PRP) surface modified PHA fibrous membranes was demonstrated to be effective for the healing and integration on tendon to bone interface.
References
References
- M.-L. Cheng, C.-C. Lin, H.-L. Su, P.-Y. Chen, Y.-M. Sun, Polymer, 49, 546-553 (2008)
- M.-L. Cheng, P.-Y. Chen, C.-H. Lan, Y.-M. Sun, Polymer, 52, 1391-1401 (2011)
Functional Bio-based Elastomers from Eucommia ulmoides
Graduate School of Engineering, Osaka University, Japan
Email: uyama@chem.eng.osaka-u.ac.jp
INTRODUCTION: Eucommia ulmoides accumulates trans-1,4-polyisoprene (TPI) in the leaves,
bark, root, and fruit coatings, which exhibits higher modulus and less flexibility than cis-1,4-
polyisoprene. This study deals with modification of TPI and applications of the modified bio-based
elastomers. Shape memory function provided the dynamically crosslinked network formation of
TPI.
METHODS: Grafting of maleic anhydride onto TPI was performed in 1,2-dichlorobenzene, and the
subsequent hydrolysis gave maleated trans-1,4-polyisoprene (MTPI). TPI containing primary
hydroxyl group (TPI-OH) was prepared by the reaction of MTPI and 3-amino-1-propanol.
RESULTS & DISCUSSION: Increasing trend of the grafted maleic moiety was observed with
increasing the concentration of maleic anhydride in the grafting reaction. With increase in maleic
content, the glass transition temperature of the resulting polymer increased, whereas the
crystallinity decreased. The maximum stress of the MTPI with carboxylates was larger than that of
the protonated MTPI. Above the melting temperature, the Young's modulus of MTPI with
carboxylates was higher than that of neat TPI and the protonated MTPI, due to dynamically
crosslinked network structure. Furthermore, the MTPI with carboxylates exhibited excellent shape
memory-recovery properties, exploiting the combination of the physical crosslinking and the
melting of the crystal. TPI-OH was crosslinked by blending with tin(II) octanoate. TPI-OH-Sn was
found to swell in tetrahydrofuran to form an organogel, whereas dissolve by adding hydrochloric
acid solution. Stress of TPI-OH-Sn was enhanced compared with that of TPI-OH. These materials
are expected to contribute to the development of bio-based intelligent elastomers.
PEGylated Silica Nanocapsules for Biomedical Application
Synthesis and Integration Capability Group, Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), Singapore
Email: x-li@imre.a-star.edu.sg
INTRODUCTION: A large variety of marine organisms, such as diatoms and sponges, form their silica skeleton in water at neutral pH and room temperature. Inspired by those biosilification processes, we have successfully developed a method to synthesize PEGylated silica nanocapsules at room temperature and near-neutral pH aqueous environment by using PEO-based block copolymer micelles as templates.
METHODS: The success of this approach lies on the confinement of silica shell growth at interface between core and corona of polymeric micelles as a result of encapsulation of silica precursors inside the core of the micelles. Functional silica capsules with fluorescent dye or magnetic particles encapsulated into their cores are prepared by mixing the dyes and particles with the PEO-based polymer and silica precursor.
RESULTS & DISCUSSION: The synthesized silica nanocapsules are intrinsically covered by a layer of free PEO chains, which enable them to exhibit excellent colloidal stability and antifouling property. The PEGylated silica nanocapsules are truly nanosized, which are ~15 nm in sizes, and demonstrated to be non-cytotoxic. These PEGylated silica nanocapsules can be further functionalized by encapsulating hydrophobic compound inside their core. For example, fluorescent conjugated polymers have been successfully loaded into the core of the silica nanocapsules. Magnetic silica nanocapsules have been prepared by encapsulating hydrophobic iron oxide (Fe3O4) nanocrystals in their cores. With low cyto-toxicity and high colloidal stability, the achieved silica nanocapsules are demonstrated to be excellent candidates for fluorescence and magnetic resonance cellular bioimaging
Ultrahigh-performance, Transparent Bioplastics Exceeding Conventional Petroplastics
1School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai Nomi, Ishikawa 923-1292, Japan
2Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki, 305-8572, Japan
3JST, ALCA, Tokyo102-8666, Japan
Email: kaneko@jaist.ac.jp
Bio-based polymers obtained by a polymerization of biomolecules are indispensable for establishment of green sustainable society where bioplastics would be applied in various fields. Improvement of functions and performances for bioplastics is very important. Polymer for high performance plastics are composed of aromatic backbones. However aromatic polymers based on petroleum industry were generally expensive. For example, aromatic polyamides and polyimides occupied series of highest heat resistant plastics whose price are much higher than food additives such as aspartame which is based on microorganismal fermentation. This comparison says that replacement of aromatic polyamide and polyimide from petroleum-base into bio-base reduced their costs and prices. On the other hand, conventional bio-based polymers were aliphatic like poly(lactic acid)s seriously completing against commodity-type plastics. In order to solve this problem, we have prepared aromatic polyesters from biochemical coumarate derivatives with rigid backbones, which demonstrating that cinnamoyl structure was rigid enough to show heat-resistance higher than 150 °C. [1-3]
Here we used 4-aminocinnamic acid (4ACA) which was bioavailable by a microorganism engineering. The photodimer of 4ACA was prepared via [2+2] cycloaddition, which is a kind of biological dianilines after carboxylate groups were protected by methyl esters or some groups. The dianilines were indispensable for preparation of the aromatic polyamide and polyimide but generally were very difficult to produce by a direct method of fermentation. The biodianilines were polymerized with diacids to produce aromatic polyamides and with tetraacid dianhydrides to produce aromatic polyimides. Especially the polyimides derived from the photodimer and cyclobutanetetracarboxylic dianhydrides showed a good thermomechanical performance as well as low density around 1.2 g/cm3, and additionally showed a high transparency [4]. These mechanical performances are higher than those of conventional transparent polymers, in spite of limited molecular design by bio-based molecules.
References
- T. Kaneko et al. Nature Mater, 5, 966 (2006).
- M. Chauzar, and T. Kaneko et al. Adv. Funct. Mater. 22, 3438 (2012)
- S. Wang, and T. Kaneko et al., Angew. Chem. Int. Ed. 52, 11143 (2013).
- P. Suvannasara, and T. Kaneko et al. Macromolecules, 47, 1586 (2014).
Seawater Based Industrial Biotechnology for PHA Production
School of Life Sciences, Tsinghua University, Beijing 100084 China
e-mail: chengq@mail.tsinghua.edu.cn
Due to the higher production cost, PHA can not compete with petrochemical plastics. Therefore, it is very important to develop low cost production technology for PHA marketing. Recently, we have succeeded in isolating halophile Halomonas spp. that are able to grow in seawater utilizing mixed substrates such as kitchen waste under unsterile and continuous processes. We have developed genetic engineering tool to assemble pathways for effective production of PHBV from glucose as the only C-source, and to change the bacterial shapes for making biomass recovery easier. The PHA production by synthetic Halomonas spp. based on seawater allows several important advantages including fresh water saving, energy saving, reduction on process complexity and increasing on process efficiency. This process can at least save 50% PHA production cost. At the moment we are conducting process scale up in an industrial setting.
References
- Dan Tan, Qiong Wu, Jin-Chun Chen, Chen GQ. Engineering Halomonas TD01 for Low Cost Production of Polyhydroxyalkanoates. Metabolic Engineering 26 (2014) 34–47
- Wang Y, Yin Jin and Chen GQ. Microbial Polyhydroxyalkanoates, Challenges and Opportunities. Current Opinion in Biotechnology 30 (2014) 59-65
- Yin Jin, Fu XZ, Wu Q, Chen JC and Chen GQ. Development of an Enhanced Chromosomal Expression System Based on Porin Synthesis Operon in Halomonas TD01. Applied Microbiology and Biotechnology DOI 10.1007/s00253-014-5959-1
- 4. Fu XZ, Tan D, Aibaidula G, Wu Q, Chen JC and Chen GQ. Development of Halomonas TD01 as A Host for Open Production of Chemicals. Metabolic Engineering 23 (2014) 78-91
Determination of biobased content for plastics or rubber products and its ISO international standardezation
National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki, 305-8565, Japan
Email: m.kunioka@aist.go.jp
The biobased content is the index of the amount for biomass-based compound in plastics or rubber products. The determination methods of biobased contents such as biobased carbon content, biobased synthetic polymer content and biobased mass content based on ISO 16620 series for plastics or ISO 19984 series for rubber products were explained. ISO 16620 and 19984 series are discussed in ISO technical committee TC61 (Plastics) and TC45 (Rubber and rubber products).
Bio-based Polymers: From Research to Commercial Applications
Sinopec Research Institute of Petrochemical Technology, Shanghai 201208, China
Email: JamesWang.sshy@sinopec.com
INTRODUCTION: Effective utilization of natural polymers offers a potential solution to address the global sustainability challenge. However, the commercial applications of bio-based polymers often encountered economic and technology challenges including high cost, lacking performance and processability. Therefore, it is critically important to develop economically attractive and technically performing bio-based polymers to meet the market demand for green polymers.
METHODS: To achieve economic advantage and renewability, low cost natural polymers including cellulose and starch were used as starting materials, these material were first converted into thermoplastic cellulose (TPC) or thermoplastic starch (TPS) by chemical, biochemical or physical techniques. TPC and TPS were further engineered with a number of biodegradable or bio-based polymers to improve performance and melt processability. Highly compatibilized materials were also developed and evaluated.
RESULTS: Bio-based materials having good melt processability and properties were developed. These materials were based on TPC and TPS and a variety of biodegradable polymers. Innovative polymer processing methods were also developed. Both composition and process conditions were found to have significant effects on the performance and processability of bio-nbased materials. Unique microstructures and nano-structures were obtained which led to surprising improvement in material properties.
DISCUSSION: Engineered multi-component systems with desired balance of performance, cost and processability were important for developing industry-meaningful bio-based materials. Thin films were developed for sustainable packaging applications.
Synthesis and Properties of Polysaccharide Ester Derivatives
Science of Polymeric Materials, Department of Biomaterial Sciences,
Graduate School of Agricultural and Life Sciences, The University of Tokyo, Japan
CREST/JST, Japan,
RIKEN Institute/Spring-8, JAPAN
Email: atiwata@mail.ecc.u-tokyo.ac.jp
The increasing environmental and economic concerns on the utilization of petrochemicals have led researchers to rely on plant biomass as a feedstock for the synthesis of polymeric materials. Over the past decades, plant biomass has been recognized as one of the most important and cheap sources of renewable polysaccharides such as cellulose, chitin, and starch. It is well known that polysaccharides do not exhibit thermoplastic properties, because of their strong inter- and intra-molecular hydrogen-bonding.
Recently, our group succeeded to synthesize new thermoplastics from polysaccharides such as xylan, glucomannan, curdlan, pullulan, etc by esterification and found interesting thermal, mechanical, optical properties. Xylan is the most abundant hemicellulose with mainly beta-(1→4) linked xylose. Konjac glucomannan (GM) is isolated from tubers of Amorphophallus konjac plants and consists of beta-(1→4) linked D-glucose and D-mannose residues and the molecular ratio of glucose to mannose has been reported to be ca. 1.6. Curdlan is a linear polysaccharide with beta-(1→3) linked glucose produced by Alcaligenes faecalis. Pullulan is a water-soluble extracellular polysaccharide produced by strains of fungus Aureobasidium pullulans, consisting of a chain of maltotriose units that alternate regularly between alpha-(1→6) linkages.
In this paper, xylan, glucomannan, pullulan, and curdlan ester derivatives are synthesized and thermal and mechanical properties are investigated. Furthermore, in the case of xylan ester derivatives, a possibility as bio-based nucleating agents for PLLA and PDLA is presented.
Furthermore, more recently, we synthesized aromatic bio-based polymers from caffeic acid extracted from coffee beans and rice bran, respectively, and found some interesting thermal behaviors of these polymers.
Biodegradable Copolyesteramides of L-Lactic Acid and ε–Caprolactam Oligomers
1Department of Chemical and Materials Engineering, Faculty of Engineering, Rajamangala University of Technology Thanyaburi, Thailand
2Department of Biobased Materials Science, Kyoto Institute of Technology, Japan
Email: sommai.p@en.rmutt.ac.th
INTRODUCTION: An increase of plastic production is considered as a serious source of environment pollution from their wastes. Most of them are produced from fossil resource and are non-degradable. Recently, research and investigation have been focus on discover and development of new polymers that are friendly to environment. Poly(lactic acid), (PLA) is a biodegradable semicrystalline polyester having mechanical property comparable to the commercial polymers. However, PLA has limitations on its brittleness, insufficient impact strength and low thermal stability. In order to improve its properties, we studied the synthesis of copolyesteramide having amide parts in the lactic acid chains.
METHODS: Blocked copolyesteramide was synthesized from copolymerization reaction of L-lactic acid oligomers (OLLA) and ε-caprolactam oligomers (OCLM). The OLLA was synthesized via direct polycondensation of L-lactic acid using Tin (II) Chloride (SnCl2•2H2O) catalyst under reduced pressure. The OCLM was synthesized from ε-caprolactam using sodium hydride (NaH) catalyst under nitrogen atmosphere. Copolymerization of OLLA and OCLM with various ratios of OLLA:OCLM was carried out using N-Acetyl caprolactam catalyst. The effect of reaction temperature and pressure on component ratios and property of copolymer was studied.
DISCUSSION: The copolyesteramide synthesized was analyzed its chemical structure to confirm ratios of ester parts and amide parts in the polymer molecules. It was found that high polymerization temperature led to degradation of amide parts due to lower activation energy of reverse reaction of amide bonds than ester bonds resulted in less component of amide part remained in the copolymer molecules. The reaction time of copolymerization longer than 12 h also led to degradation of copolymer synthesized. The copolyesteramide can be used as a compatibilizer for blending of poly(lactic acid) and nylon polymer for polymer blends application.
Composite polysaccharide scaffolds for spatial distribution and sustained growth factor delivery
1Department of Biomedical Engineering, National University of Singapore, Singapore
2INSERM, U791 Center for OsteoArticular and Dental Tissue Engineering, Nantes, France
3Mechanobiology Institute Singapore, National University of Singapore, Singapore
4Department of Surgery, National University of Singapore, Singapore
Naturally derived polysaccharides are biocompatible, non-antigenic, non-immunogenic. Polysaccharides of non-animal origin such as pullulan, dextran, alginate and chitosan can easily recapitulate the polysaccharide component of the extracellular matrix in human tissues without potential disease transmission, and as such have important uses in tissue engineering. For instance, polysaccharides can be chemically crosslinked to form hydrogels with high water content to mimic soft tissues. Pullulan-dextran (PD) polysaccharide hydrogels are known to support endothelial progenitor cell growth. Due to the high charge density of polysaccharides, it is also possible to use them for the formation of interfacial polyelectrolyte complexation (IPC) fibers, which can be used for the sustained delivery of hydrophilic biomolecules. IPC fibers made with chitosan and alginate were previously demonstrated to regulate the temporal release of growth factors.
A composite scaffold was created to combine the characteristics of PD hydrogel and chitosan-alginate IPC fibers for controlling cell spatial distribution and growth factor delivery. Fibronectin, bovine serum albumin (BSA) and vascular endothelial growth factor (VEGF) were easily incorporated into the IPC fibers by addition into either positively-charged chitosan or negatively-charged alginate before fiber drawing. The collected IPC fibers were embedded into a PD solution mixed with food-grade crosslinker. Ultrastructure of PD-IPC composite scaffolds showed the integrity of each component. PD-IPC scaffolds with fibronectin sustained the proliferation of human fibroblasts for 7 days and exhibited preferential attachment of cells on the IPC fibers. PD-IPC scaffolds incorporated with either BSA or VEGF showed sustained release. BSA achieved a near-linear release profile for 2 months when released from PD-IPC scaffolds, compared with bare IPC fibers. VEGF released from PD-IPC scaffolds exhibited sustained release for 1 week and retention of bioactivity by stimulating endothelial cell proliferation. The polysaccharide composite scaffolds would have various potential applications in tissue engineering and sustained delivery of biologics.
Environmental degradation of aliphatic polyesters
Division of Molecular Science, Graduate School of Science and Technology, Gunma University.
Aliphatic polyesters gather attention as candidate biodegradable materials. Both bacterial aliphatic polyester, poly(3-hydroxybutyrate)(P(3HB) and chemosynthetic aliphatic polyester, poly(ethylene succinate) (PESu) could be degraded by P(3HB) depolymerases, indicating that both polymers are recognized as substrate by the enzymes. Although PESu is thus susceptible to degradation by P(3HB) depolymerase in vitro, it has been reported that the environmental degradation does not always occur. On the other hand, P(3HB) degraded by same enzyme, has been known to be degraded in almost all environments tested. So in order to determine the cause we investigated the distributions of PESu- and P(3HB)-degrading bacteria in various environments: 61 locations. We therefore isolated 12 P(3HB)- and 16 PESu-degrading strains. Phylogenetic analysis revealed that P(3HB)-degrading bacteria were composed of the phyla Proteobacteria, Actinobacteria, and Firmicutes, while that the majority of PESu-degrading bacteria was the genus Bacillus. Only 1 strain of all isolates could degrade both substrates. This suggests that PESu is not degraded by any P(3HB) depolymerases but other enzyme in environments.
We also synthesized 3 polylactone(polyvelerolactone(PVL), polyenentholacton(PEL), polycaprylolacton(PCyL))s and evaluated their BOD-biodegradabilities and enzymatic degradabilities. The results of BOD-biodegradations for them suggest that their degraders did not always use their hydrolysates, and that the polylactones would be mineralized by symbionts in environments.
Crossing the biomass for novel bio-sourced semi-aromatic polyesters
1University of Bordeaux, Laboratoire de Chimie des Polymeres Organiques, France
2CNRS, Laboratoire de Chimie des Polymeres Organiques, France
3Bordeaux INP, Laboratoire de Chimie des Polymeres Organiques France
*Email: cramail@enscbp.fr
INTRODUCTION: Petrol depletion and environmental concerns lead the chemical industry to consider renewable resources as building blocks for the synthesis of polymers. Among the available bio-resources, vegetable oils have been intensively studied for the synthesis of bio-based polymers because of their good availability. However, due to their inherent aliphatic structures, polymers obtained from fatty acid derivatives generally exhibit restricted thermomechanical properties. It is thus important to investigate other bio-based molecular platforms (for instance, lignin) to broaden the palette of renewable polymers.
METHODS: Lignin, the second most abundant renewable polymer after cellulose, is a source of phenolic compounds after depolymerization. In order to develop novel difunctional aromatic synthons, phenolic substrates potentially derived from lignin were dimerized via a "green" enzymatic process enabling the synthesis of biphenyl compounds in large quantity and high yield. Further chemical modifications of these biphenyl dimers yielded a bio-platform of aromatic derivatives ready for polymerization. For instance, semi-aromatic polyesters were prepared by copolymerization of biphenyl diols with various diesters derived from fatty acids and ADMET polymerization of bis-unsaturated biphenyl derivatives, produced by esterification of methyl vanillate dimer with undecenol, yielded materials with good thermal stability over 300°C.
DISCUSSION: In the talk, the green synthesis of a series of difunctional biphenyl substrates will be first presented. Second, the structure-properties relationship of the bio-based semi-aromatic polyesters obtained by cross polymerization of fatty acid-based and lignin-based difunctional monomers will be discussed.
Oral Presentations
Fixation and Reutilization of CO2 Emitted through Sugar Degradation into Poly(3-hydroxybutyrate) in Ralstonia eutropha under Heterotrophic Conditions
1Dept. Bioeng., Grad. Sch. Biosci. & Biotechnol., Tokyo Institute of Technology, Japan
2Dept. Biotechnol., Grad. Sch. Eng., Osaka University, Japan
Email: tfukui@bio.titech.ac.jp
INTRODUCTION: Ralstonia eutropha H16 is a facultative chemolithoautotrophic bacterium, and well known to produce poly(3-hydroxybutyrate) [P(3HB)] efficiently from sugars. Previous studies have reported partial derepression of Calvin-Benson-Bassham (CBB) cycle in R. eutropha on fructose and gluconate, and recent omics analyses suggested that the cycle is turned during the heterotrophic P(3HB) biosynthesis on fructose. This study investigated the ability of R. eutropha to fix and re-utilize CO2 emitted from sugars through Entner-Doudoroff (ED) pathway.
METHODS: R. eutropha H16G, an engineered strain of H16 for glucose assimilation, was incubated with [1-13C1]-glucose, and the 13C-labeling profiles of various metabolites and P(3HB) were determined by mass-spectrometric analyses.
RESULTS: R. eutropha H16G accumulated P(3HB) with 13C-abundance of 5.6% from [1-13C1]-glucose, which was significantly higher than those by the CBB cycle-inactivated strains. The metabolomics clarified that the [1-13C1]-glucose-derived 13C was incorporated into most metabolites, including ribulose-1,5-bisphophate and 3-phosphoglycerate which are key CBB cycle metabolites in H16G more than those in the mutant strains. The carbon yield of P(3HB) by H16G was 117~123% of those by the mutants, which was agreed with the possible fixation of the CO2 molecules (0.93 CO2) estimated from the balance of energy and reducing equivalents in ED pathway integrated with CBB cycle.
DISCUSSION: The present results provided a new insight into the role of CBB cycle; the "gratuitously" activated CBB cycle in R. eutropha under aerobic heterotrophic conditions participated in fixation and reutilization of CO2 emitted by oxidative decarboxylation of pyruvte during sugar degradation, leading to an advantage in the increased carbon yield of the storage compound, P(3HB).
Valorization of waste glycerol to polyhydroxyalkanoate by Bacillus thuringiensis EGU45 under non-nitrogen limiting conditions
Microbial Biotechnology and Genomics, CSIR -Institute of Genomics and Integrative Biology (IGIB), Delhi University Campus, Mall Road, Delhi-110007, India.
E-mail: prasun.kumar@igib.in
INTRODUCTION: Polyhydroxyalkanoates (PHAs) have drawn attention due to its similarity to plastics. Its global demand is 34,000 MT, although their large scale production is limited by costly feed and recovery process. Crude glycerol (CG), generated at the rate of 10% of the total biodiesel produced may serve as a cheap raw material for PHAs production. Here, we report the potential of Bacillus thuringiensis to utilize high CG as feed for PHA co-polymers production at high N containing medium.
METHODOLOGY: PHA production by B. thuringiensis EGU45 was studied on three different media: NB, GM2, and M-9 supplemented with various inorganic nitrogen (N) sources. CG (1 -10%) was supplemented with different components of NB as N sources. The PHA was later analyzed by TEM, GC, GPC, NMR and FTIR.
RESULTS: B. thuringiensis EGU45 was found to produce 1.5-3.5 g PHA/L from feed containing 1-10% CG and NB without any acclimatization. Here, the PHA yields were 56-72% of the total biomass. B. thuringiensis EGU45 could produce PHA at the rate of 1.5-1.8 g/L, from 1% CG on media having high N contents. B. thuringiensis EGU45 was able to produce co-polymer of P(87% 3HB-co-13% 3HV) on high N containing feed supplemented with propionic acid. B. thuringiensis EGU45 grown on peptone+YE supplemented with 1% CG showed large PHA inclusions (0.75-1.25 μm) within the cells. The PHA produced on CG was found to have a Mw of 3.85 X 105 Da with a polydispersity index of 2.1.
CONCLUSION: The use of B. thuringiensis EGU45 towards efficient conversion of CG to PHA without the necessity of limited amount of N and pH controls could improve its feasibility at large scale with a flexible harvesting time. Further, integration of H2 and PHA production processes by exploiting functional consortium of Bacillus can increase the process efficiency.
An update on bio-based polymers derived from plant sources
Department of Bio-Engineering, Birla Institute of Technology, Mesra, India
Email: archana.bioinfo87@gmail.com
INTRODUCTION: This paper focuses on the latest technology and trends of bio-based polymers derived from plant sources. Recent advances in natural biopolymer development, plant genetic engineering and other composite plant science offer valuable opportunities which enhanced the support of environmental safety. Nowadays, Bio-based polymers are replacing the existing polymers in a number of applications. For scientific community the real challenge lies in finding applications which would consume sufficiently large quantities of these plant derived biopolymers which also compete economically in the market.
METHODS: In this paper we will highlight recent progress of plant-based biopolymers like PHAs, silk, elastin, collagen, and cyanophycin with an emphasis on the synthesis of PHB. We will focus on the range of biobased polymers, also focusing on advanced methods of biopolymer production and their commercial applications. High production of PHB can be achieved by the modification in the promoter region, which regulate the expression of transgenes and also play an essential role in controlling the metabolic pathways.
RESULTS: These experiments have improved our understanding of bio-based polymer derived from plants and the role of different plant parts that is useful for the production of bio-based polymer and other novel molecules. The paper inspects not only the future challenges, but also discuss technological problems together with potential solutions.
DISCUSSION: Manufacture of bio-based polymers from plants will enhance the demand of agricultural waste. Various aspects and properties of bio-based polymers and recent developments of different bio-based polymers and other bio composites are discussed in this article. Bio-based polymers have provided the new opportunity to the scientists for possible solutions regarding environmental safety problems. Cost effective bio-based polymer can be produced through constant determinations of scientists and R&D supports.
Biosynthesis of Medium Chain Length Homo Polyhydroxyalkanote from Plant Biomass
Department of Innovative and Engineered Materials, Tokyo Institute of Technology, Japan
INTRODUCTION: Medium chain length homo polyhydroxyalkanoate (MCL-homo-PHA) is homopolymer of 3-hydroxyalkanoate with 6~14 carbon number, and is reported as a new types of bioplastic synthesized by metabolically engineered bacterium. A different point from conventional PHAs and poly (lactic acid) is that it can be processed into a soft transparency film, therefore new use application is expected. On the other hand, as to its biosynthesis process, low productivity and high cost of polymer carbon source are problems. In this study, to solve these problems, optimization of biosynthesis process was performed.
METHOD: To improve the productivity, bacterial hosts and culture conditions (medium and sugar source) were validated. A construction of PHA synthesis pathway was performed by introducing exogenous genes; acyl-CoA synthase (ACSPp), PHA synthase (phaC1Pp) from Pseudomonas putida KT2440 and enoyl-CoA hydratase (phaJ4Pa) from Pseudomonas aeruginosa into bacterial hosts. For the cultivation, fatty acid (decanoate or dodecanoate) was added as a polymer precursor and harvested after three days. Intracellular PHA content and polymer composition were determined by gas chromatography. To solve the high cost of purified fatty acid, crude mixed fatty acid, by-product of pail kernel oil (PKFAD) containing 50% dodecanoic acid and modified PKFAD by urea treatment were used and cultured to get C12-rich-PHA.
RESULTS: By the optimization of bacterial hosts and culture conditions, productivity was increased up to 1.88 g/L of C10-homo-PHA and 1.06 g/L of C12-homo-PHA. This value of C10 polymer is the highest thus far recorded. Polymer synthesis using PKFAD and modified PKFAD achieved 60-80 mol% and 80-90 mol% C12-rich-PHA respectively.
DISCUSSION: In this study, 1) the use of E. coli with enhanced fatty acid metabolism and 2) the separation of cell growth phase and polymer synthesis phase contributed to increased production of MCL-homo-PHA. The material properties of C12-rich-PHA produced by crude biomass and C12-homo-PHA are under investigation.
Intracellular Delivery of Proteins into Living Plants via Fusion Peptides
1Enzyme Research Team, Biomass Engineering Program Cooperation Division, RIKEN Center for Sustainable Resource Science, Japan.
2School of Biological Sciences, Universiti Sains Malaysia, Malaysia.
3Center for Bioscience Research and Education, Utsunomiya University, Japan
Email: kiawkiaw.ng@riken.jp
Abstract not available online
Designing Wheat Gluten Based Materials
1Department of Chemistry, KU Leuven, Belgium
2Laboratory of Food Chemistry and Biochemistry, KULeuven, Belgium
3Leuven Food Science and Nutrition Research Centre (LFoRCe), KU Leuven, Belgium
4Department of Chemical Engineering, KU Leuven, Belgium
Email: thomas.langstraat@chem.kuleuven.be
INTRODUCTION: Various characteristics of wheat gluten proteins, such as availability, unique intrinsic properties and biodegradability, make them attractive candidates for designing sustainable materials. The unique functionality of wheat gluten stems from its very high molar mass and the presence of cysteine amino acid residues, which upon heating provide the polymeric system with intermolecular disulfide crosslinks. Here, we demonstrate that with the use of proper additives one can obtain gluten based materials with properties that range from stiff to rubbery.
METHODS: A stiff material was produced by compression molding gluten with low levels of plasticizer. Routes for improving the ductility of the stiff material by manipulating the native protein structure were explored. In contrast, a rubbery thermoplastic vulcanizate (TPV) material was produced by extruding a gluten rubber precursor with a thermoplastic polymer, and subsequently injection molding to give a final product. Adhesion between the two phases was optimized by reactive compatibilization.
RESULTS: The mechanical performance of stiff gluten materials was significantly improved by processing the proteins in denaturing conditions prior to molding. Molecular entanglements and polymer secondary interactions appeared to be increased and the material exhibited strain hardening under compressive loads. The TPV material had a finely dispersed particle morphology and showed excellent elongation in tensile tests as well as good mechanical recovery.
DISCUSSION: Proteins are complex macromolecules with inherent folded structures, a diverse mix of functional monomers and a vulnerability towards degradation at high temperatures. With this in mind, polymer processing approaches need to be adapted and tailored in order to realize the potential of protein based materials. We have shown that high modulus materials approaching engineering polystyrene, as well as elastomers for the 'soft touch' industry, can be produced from a common protein feedstock. End of life options for both classes of materials have also been considered.
Properties of PBSA/Kenaf Fiber Green Composites - Effect of Kenaf Fiber Surface Treatment
Department of Chemical and Materials Engineering, Chang Gung University, Taiwan
Email: maxson@mail.cgu.edu.tw
INTRODUCTION: Biopolymers have attracted much attention during the past decade due to their eco-friendly characteristic. Poly(butylene succinate-co-butylene adipate) (PBSA) possesses biodegradable character, and show potential in certain applications. However, some intrinsic disadvantages have limited its applications. To improve the properties of PBSA, natural kenaf fibers (KFs) were used as the reinforcing material to develop the so-called "Green Composites".
METHODS: The as-received chopped kenaf fibers were ground first, and then were water-cleaned or further treated with NaOH (6%) before being mixed with PBSA by using Haake internal mixer. The samples were prepared at 140 °C for 8 min at a rotors speed of 60 rpm. The loadings of KF in the composites are 10, 20, 30, and 40 wt%, respectively. The morphology and thermal/mechanical properties of prepared samples were characterized and compared with one another
RESULTS & DISCUSSION: Scanning electron microscope images revealed that both types of the KFs were distributed evenly within the PBSA matrix, and the alkali-treated KFs exhibited stronger adhesion with PBSA compared with the water-cleaned KFs. Thermogravimetric analyzer results showed that the thermal stability of the composites was slightly lower than that of neat PBSA, due to the lower degradation temperature of KFs. Differential scanning calorimeter analysis illustrated that the crystallization temperature (Tc) of PBSA shifted to a higher temperature as the loading of KFs increased. The melting temperature of PBSA changed little after the formation of composites. Tensile properties test showed that the Young's modulus of the composites was evidently higher than that of neat PBSA. A higher loading of KFs led to an even higher Young's modulus. The alkali-treated KFs exhibited a higher efficiency in enhancing the Young's modulus of PBSA compared with water-cleaned KFs.
Chemo-enzymatic Synthesis of Functional Cationic Peptides for Gene Delivery
Enzyme Research Team, Biomass Engineering Program Cooperation Division, RIKEN Center for Sustainable Resource Science, Japan
Email: jose.ageitos@riken.jp
INTRODUCTION: The study of artificial vectors for gene delivery is emerging in the biotechnology field. Examples of artificial vectors are the cationic peptides (CPs) composed by L-lysine (Lys) and L-arginine (Arg). Thereby, CPs can form complexes with DNA via ionic interactions and induce its internalization by cells. With the aim to simplify the production of CPs for gene delivery, the present work developed a chemo-enzymatic reaction which enabled the synthesis of linear and branched CPs. Cytotoxicity and transfection efficiency of the chemo-enzymatically synthesized CPs were evaluated for their novel use as gene delivery agents.
METHODS: Synthesis of linear and branched CPs was performed by chemo-enzymatic synthesis mediated by proteinase K. Degree of polymerization of peptides was characterized by NMR and MALDI-TOF. In order to observe the applicability of synthetized CPs, it was tested their ability to form ionic complex and gene transfection with 2 types of plasmid DNA (pDNA) encoding the reporter genes for luciferase and green fluorescent protein. Toxicity and transfection efficiency of CPs were evaluated with human embryonic kidney 293 cells.
RESULTS: We have optimized the synthesis of linear and branched oligo(Lys), oligo(Arg) and oligo(Lys-r-Arg) mediated by proteinase K in aqueous solution. Oligo(Lys) and oligo(Arg) showed higher transfection efficiency than the other assayed CPs. Branched CPs did not increase the transfection efficiency, even observed an increase in the pDNA complexation. The present results were similar to the ones previously reported for pDNA complexes of chemically synthetized oligo(Lys) and oligo(Arg).
DISCUSSION: In the present work, using proteinase K, we have synthetized linear and branched CPs in one-pot reaction without using organic solvents or deprotection steps. Synthetized peptides exhibit transfection efficiencies comparable to previously reported monodisperse CPs. The results show that chemo-enzymatic synthesis opens the door for efficient production of CPs for their use as gene delivery carriers.
Structure and Properties of Cellulose Nanofibers by Mechanical and Chemical Nanofibrillations
1Graduate School of Engineering, Kobe University, Japan
2CREST, Japan Science and Technology Agency, Japan
*Email: tnishino@kobe-u.ac.jp
INTRODUCTION: Natural cellulose is contained in plant tissue and the most abundant biomass resource, and well known to possess biodegradability. So, cellulose attracts a great deal of attention to be used as alternative resources of fossil fuels and chemical products. Cellulose nanofibers (CNF) reveal light weight, high mechanical properties, low linear thermal expansion coefficient. For exploiting these advantages, CNF are expected to be utilized in high performance material fields.
Preparing methods of CNF are roughly divided into two ways, mechanical and chemical treatments, CNF prepared by various methods are considered to possess different structure and properties.
In this study, we employed grinding process as mechanical method and 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-mediated oxidation as chemical method, respectively. Thermal, mechanical and optical properties were compared for CNF prepared by grinding method (G-CNF) and those prepared by TEMPO-mediated oxidation method (TOCN).
METHODS: Refined kenaf microfibers are used as starting cellulose source. They were dispersed in distilled water and run into the grinder. As chemical method, refined kenaf microfibers were dispersed in distilled water with sodium bromide, TEMPO and sodium hypochlorite. TEMPO-mediated oxidation was started by keeping the dispersion at pH 10 by adding sodium hydroxide. After the reaction, TEMPO oxidized microfibers were dispersed in buffer, then added sodium chlorite and stirred another 48h. After that, TEMPO oxidized microfibers were fibrillated by blender.
RESULTS & DISCUSSION: The fiber diameter (φ=4.2nm) of TOCN was smaller than that (φ=33nm) of G-CNF, which brought high transparency and high mechanical properties to TOCN. On the other hand, G-CNF sheets showed high toughness and maintained high thermal stability of starting cellulose. These results reveal that structure and properties of CNF were controllable by preparing methods, and CNF complied with utilization purpose could be prepared.
Multifunctional Materials Based on Crosslinkable Poly(Lactic Acid) Dispersions
1Solutions for Natural Resources and Environment, VTT Technical Research Centre of Finland Ltd., Finland
2Customer Solutions, VTT Technical Research Centre of Finland Ltd., Finland
Email: adina.anghelescu-hakala@vtt.fi
INTRODUCTION: Poly(lactic acid) (PLA) and its copolymers are some of the most extensively studied bio-based synthetic polymers. Traditionally, the market of PLA-based polymers has been in the biomedical field, but more recently they have also gained increasing interest on other application areas such as packaging. Low molecular weight PLA lacks mechanical properties required to form and maintain a uniform coating layer in barrier applications. These obstacles can be overcome by crosslinking of low molecular weight PLA during or after dispersion preparation. In this work, to avoid organic solvents aqueous dispersions of crosslinkable PLA were prepared by using a thermomechanical method. The developed formulations are suitable solutions as crosslinkable coatings for packaging and encapsulation systems.
METHODS: A low molecular weight copolymer was synthesized by polycondensation of D,L-lactic acid with 1,4-butanediol and itaconic acid. Radical crosslinking reactions of synthesized polymers were investigated in order to find formulations suitable for a rapid crosslinkable coating. Aqueous dispersions were prepared from the polymer with a solvent-free thermomechanical method. The method inherently leads to dispersions with high solid content.
RESULTS: When crosslinking reactions were conducted after the dispersion preparation, the formulations were coated onto commercial carton board. The properties of the coatings were investigated in term of water vapor transmission and grease resistance. In the case that crosslinking reactions take place during dispersion preparation, the microparticles dispersions were tested for encapsulation of non-water soluble compounds.
DISCUSSION: The developed PLA-based materials showed very good grease resistance and moderate water vapor barrier properties. These indicate a solid performance for packaging of especially dry and fatty goods. In addition, the microparticle dispersions tested as encapsulation systems showed high encapsulation efficiency (>90%).
Temperature dependence of the elastic modulus of the crystalline regions and high melting point of poly(glycolic acid)
Department of Chemical Science and Engineering, Kobe University, JAPAN
*Email: tnishino@kobe-u.ac.jp
INTRODUCTION: Poly(glycolic acid)(PGA) is the simplest aliphatic polyester with high mechanical properties, biodegradability, biocompatibility with extraordinary high melting point (Tm: 223°C). PGA skeleton is reported to be planar zigzag in the crystalline regions. The elastic modulus of the crystalline regions (crystal modulus) in the direction parallel(El) and perpendicular(Et) to the chain axis give information about skeletal structure and intermolecular cohesive energy, respectively. In this study, the origin of high Tm of PGA was investigated through the El and Et measurements by X-ray diffraction. In addition, temperature dependence of the crystal modulus was investigated in the wide temperature range(13K~400K).
METHODS: PGA was compression molded into the sheet. The drawn and annealed PGA was used for the El, Et measurements. The reflection used for measuring the El was the 006 reflection, the 110, 020 reflections for the Et, respectively. The strains in the crystalline region were estimated by the changes in lattice spacing induced by the constant stress applied. The stress in the crystalline regions was assumed to be equal to the stress applied to the sample. The crystal modulus was evaluated from the inclination of the stress-strain curve of the crystal lattice. Temperature dependence of the El, Et were performed from 13K to 400K,
RESULTS: The El value of 104GPa was obtained at 300K, which is very low compared with that (235GPa) of polyethylene(PE) as planar zigzag conformation. The low El value suggests that the skeleton of PGA is not full extended, but contracted through internal rotation. The Et value ranged between 5.8GPa and 7.3GPa, which are higher than those based on van der Waals interaction. The low Et value (decrease of entropy) and high El value (increase of enthalpy) are considered to contribute to the high Tm of PGA. Temperature dependence of the crystal modulus of PGA was also investigated.
Composite Development of PLA/CCS based Polymer
Lab. Of Adhesion and Bio-Composites, Program in Environmental Materials Science
College of Agriculture and Life Sciences, Seoul National University, Gwanak-ro, Gwanak-gu, Seoul 151-921, Republic of Korea.
*Email: hjokim@snu.ac.kr
INTRODUCTION: As the carbon dioxide problem recently has emerged flushed the importance of CCS-based technologies. In particular, polymer materials based on carbon dioxide capture effect can be expected from it, as well as to explore the possibility of a new material, so large that its expectations. However, it is difficult to limit the application of the industrial performance of the polymer itself. In order to overcome this drawback and to proceed with the union of the various polymer composite material. In order to overcome this drawback, the various polymer should be composite material should be composited.
METHODS: The carbon-based polymers have a biodegradation properties due to the unique structure, and in order to highlight these features should want to make a biodegradable composite with PLA as a biodegradable polymer. The composite material of the PLA and PEC was prepared through through extrusion technique. Analyzed the mechanical properties and a condition of mixture of prepared samples.
RESULTS: When the two materials are mixed with a small percentage of the mixing properties are evaluated to be part of the expression. However, if the amount is increased at a similar level to look for incompatible properties. The physical properties of the tow materials in mechanical properties is showing a structure expressed together.
DISCUSSION: Were compared with solvent blending system to look at whether there is a problem of mixing characteristics in the extrusion process. We can check the cloud formed at a constant amount or more. The introduction of new systems capable of inducing interfacial bonding force to overcome the difference between the solubility of materials. Introducing C into A and B which are incompatible, A-C-B, or method of some forming a structure A-B can improve the compatibility.
Improved Strength of the PLA utilizing Nano-Cellulose
Lab. Of Adhesion and Bio-Composites, Program in Environmental Materials Science
College of Agriculture and Life Sciences, Seoul National University, Gwanak-ro, Gwanak-gu, Seoul 151-921, Republic of Korea.
*Email: hjokim@snu.ac.kr
INTRODUCTION: While PLA was evaluated the applicability in a variety of industries in biodegradable polymers, there is a limit to the type of application because of the ingerent brittle nature and low strength. Overcome these disadvantages and to enhance the environment-friendly polymer characteristics apply the biomass-based filler composites development is underway in various ways. There is various types of natural fibers which were applied in polymers, can see that for the composite materials using these fibers, the strength improving effect appears. However, because there is limitation of fiber contents to enhance performance and caused other performance degradation, some method is required to overcome.
METHODS: The types of nano-cellulose in various ways, but omong them was applied to the NCC. Predispersion method were utilized for nano-cellulose dispersed in PLA. The nano-cellulose was primary dispersion and secondary dispersion with PLA was played with predispersion
RESULTS: As applied to the nano-cellulose can know the mechanical strength is improved. In particular, the improvement in the tensile strength is the most effective. A difference is generated in performance improvements in accordance with the dispersion of nano-cellulose. When capred with conventional system using the composite material of the natural fiber, the effect is small.
DISCUSSION: In the existing system, the amount of the natural fiber is at least 30% fiver. Considering the performance of PLA and inique process, the contents of fiber has to be limited. Whereas, nano-cellulose is a high effect can be achieved in a small amount to within 2-3%. This feature is due to high specific surface area having a nano structure. It can be said that the unique properties of the cellulose structure can exert the most effective. Also, it is possible to implementation of transparency with small amount dispersion, the application area of PLA composites could be enlarged in various industry.
Drop-weight impact response of jute/ramie fibre reinforced hybrid composites
1School of Aerospace Engineering and Applied Mechanics, Tongji University, 1239 Siping Road, Shanghai, P R China, 200092
*Email: liyan@tongji.edu.cn
INTRODUCTION: In recent years natural fibre has been utilised as an environmentally friendly reinforcement to replace asbestos and fibreglass in strengthening thermosetting and thermoplastic polymers for various applications. Demand for greater weight saving and impact protection employing lightweight materials. There is a growing interest in the properties of cellular materials for their use in impact energy absorbing structures. However, one of the major problems that should be solved before extensively using the natural cellular materials in energy absorbing systems is the understanding of their behaviours during impact process.
METHODS: This paper experimentally studied the low-velocity impact behaviors of jute/ramie fibre fabric reinforced hybrid composites with the aim of investigation on the effect of hybrid ratios and stacking sequences on impact performance of the composites. The interlaminar properties of jute/ramie fiber reinforced hybrid composites were also investigated using a double cantilever bending test. The failure surface were observed with scanning electronic microscope (SEM).
RESULTS: The impact properties of the jute/ramie fiber reinforced hybrid composites were improved with the increasing of ramie fiber content. The stacking sequence also showed great influence on the energy absorption of jute/ramie fiber reinforced hybrid composites.
DISCUSSION: Hybridizing different plant fibers together will be an effective method of solving the problem of lacking rigidity of jute fibre reinforced composite and the high price of ramie fibre reinforced composite. Good design on hybrid composites can combine the advantages of various fibres and enhance the overall performance of the composite. Moreover, it can also prevent matrix cracking and improve the fracture toughness of the composites.
Aqueous dispersions of bio-based polyurethanes
Centre National de la Recherche Scientifique, University of Bordeaux, Laboratoire de Chimie des Polymères Organiques, UMR 5629, F-33607 Pessac Cedex, France.
Email: erix@enscbp.fr
INTRODUCTION: Vegetable oils are interesting molecules for polymer synthesis through the derivatization of their functional groups. They are easily converted into diols or polyols that can be used for the synthesis of polyurethanes (PU). In particular, PU latexes are interesting for coating and adhesive applications. In this work, we focus on a green route to non-VOC aqueous PU dispersions through miniemulsion polymerization.
METHODS: Polyurethane latex particles were synthesized by miniemulsion polyaddition of fatty acid-based diol derivatives and isophorone diisocyanate. The influence of the solid content, the surfactant and the hydrophobic agent was studied. The structure and properties of the polymers are compared between bulk and miniemulsion polymerization; regarding molar mass, urea content and thermal properties. In particular, the influence of the isocyanate/alcohol ratio on the structure and properties is thoroughly studied.
RESULTS and DISCUSSION: Stable monodispersed latex particles with diameters around 200-300nm were obtained with solid content up to 50wt%, without use of any additional hydrophobic agent. The structure study showed that there is a side reaction with water leading to urea linkages in the backbone. Thus there is no more stoichiometry between isocyanates and alcohols during polymerization, leading to poor molar masses. The isocyanate/alcohol ratio was thus increased to palliate the loss of stoichiometry. The best ratio was found to be 1.2 in terms of latex stability and molar mass. Moreover, the impact of the urea content on the PU properties is highlighted: i.e. glass transition temperature from -15°C to 70°C.
Cyclodextrin-based Supramolecular PEGylation for Protein Drugs
1Graduate School of Pharmaceutical Sciences, Kumamoto University, Japan
2Program for Leading Graduate Schools "HIGO (Health life science:Interdisciplinary and Glocal Oriented) Program", Kumamoto University, Japan
3Faculty of Pharmacy, Mansoura University, Egypt
4Nihon Shokuhin Kako Co., Ltd., Japan
*Email: arimah@gpo.kumamoto-u.ac.jp
INTRODUCTION: Polyethylene glycol (PEG) modification (PEGylation) is one of the best approaches to improve stabilities, proteolytic resistance and blood retention, etc. of protein drugs. However, PEGylation markedly decreases the activity of protein drugs. For example, PEGylated interferon, commercially available product, shows only 7% of the activity, compared to intact interferon. In the present study, we developed novel PEGylation technology through host-guest interaction between β-cyclodextrin (β-CyD) and adamantane (Ad), i.e. self-assembly PEGylation Retaining the Activity (SPRA) technology, for protein drugs.
METHODS: Firstly, PEGylated β-CyD (PEG-β-CyD) having 1-4 PEG chains (M.W. of PEG = 20 kD) per one β-CyD molecule and Ad conjugate with insulin or lysozyme (Ad-ins or Ad-lys) were synthesized. Then, Ad-ins/PEG-β-CyD complex (SPRA-ins) or Ad-lys/PEG-β-CyD complex (SPRA-lys) was prepared by mixing the both components in water. Thermal- and enzymatic-stabilities, in vitro enzymatic activity and in vivo bioactivity of SPRA-ins or SPRA-lys were examined.
RESULTS: Thermal- and enzymatic-stabilities of SPRA-ins and SPRA-lys were higher than those of intact proteins and were comparable to PEGylated proteins. Importantly, in vitro lytic activity of SPRA-lys was completely retained compared with intact lysozyme, even though the activity of PEGylated lysozyme was 23%. In addition, hypoglycemic effect of SPRA-ins was markedly prolonged compared to intact insulin without loss of the activity, whereas PEGylated insulin showed negligible hypoglycemic effect.
DISCUSSION: Currently, PEGylated insulin (M.W. of PEG = 20 kD, activity = 6%) has been in phase III clinical trials, although improvement of its activity is required. SPRA technology achieves reversible PEGylation through host-guest interaction between β-CyD and Ad, resulting in high blood retention of the proteins without loss of the activity. These results indicate that SPRA technology is useful as a novel PEGylation technique for protein drugs.
Manufacture and Evaluation of PLA based Bio-Screw
Lab. Of Adhesion and Bio-Composites, Program in Environmental Materials Science
College of Agriculture and Life Sciences, Seoul National University, Gwanak-ro, Gwanak-gu, Seoul 151-921, Republic of Korea.
*Email: hjokim@snu.ac.kr
INTRODUCTION: Recently, variety of leisure activities are increased with the recent improvement in quality of life, various and accidents caused by these activities. A prime example of this thinking is the fracture accident. The increase in cases of fracture accident trend accelerated in accordance with the acceleration of the recent aging society. If you have a musculoskeletal problem that requires surgery fixed it, where the screws are utilized. But utilize the existing screws Titanium alloy based uranium metal screws, screw technology has been introduced by the new material such as reoperation and reoperation.
METHODS: Physical properties for the evaluation of the PLA had a change in temperature and pressure conditions at the injection conditions. Also, underwent the aging process at various temperatures in order to control the crystallization after the injection molding. These variables were investigated in accordance with the change of the physical properties change.
RESULTS: The crystallization degree according to the L structure of the PLA generated dissimilarly. And the color changes were occurred according to the crystallization. Depending on the temperature and pressure is a material having a modulus and has a significant difference can be seen that thi difference is derived in accordance with inside coupling conditions.
DISCUSSION: Mechanical properties was increased with crystallization degree of polymer but, biodegradation rate may delayed. These functional elements may be said to be the most important to establish optimized conditions, due to the trade-off relationship with each other. To apply actual medical environment, it needs the appropriate level of biodegradation rate and maintaining the strength in a variety environments. And on the basis of the foregoing experiments, as well as the processing conditions may also know that the process conditions can affect the material.
Growth Factor-incorporated and Cell-laden Scaffolds Made by Concurrent Emulsion Electrospinning and Cell Electrospray
Dept. of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong
*Email: memwang@hku.hk
INTRODUCTION: There has been a widespread use of electrospun scaffolds in tissue engineering owing to their distinctive advantages. However, current electrospun scaffolds have major limitations, e.g., low cell infiltration into scaffolds. In the present study, a new method/process was developed to place cells directly in electrospun scaffolds and a growth factor was also incorporated in the scaffolds for enhancing the biological performance.
METHODS: Unlike conventional manual cell-seeding methods, cell electrospray was employed for placing cells directly and randomly in electrospun scaffolds. A coaxial electrospray facility was used for cell electrospray, forming core-shell structured microspheres with the core being an aqueous cell suspension. Sodium alginate formed the polymer shell and HUVEC cells were encapsulated in microspheres. Nanofibrous scaffolds containing a growth factor, VEGF, were electrospun using PBS/PLGA emulsion or VEGF-containing PBS/PLGA emulsion. Concurrent emulsion electrospinning and cell electrospray were performed, creating nanofibrous scaffolds with embedded cell-containing microspheres.
RESULTS: SEM examinations showed that cell-containing microspheres (100~200 μm) were randomly distributed in nanofibrous scaffolds. TEM analysis revealed that both fibers and microspheres possessed core-shell structures: PBS or VEGF-containing PBS as core in nanofibers, and cell suspension as core in microspheres. Using ELISA, VEGF showed controlled and sustained release in vitro. Through live/dead staining and fluorescent microscopy, high cell viability was observed. Cells were shown to be released from microspheres in vitro. Live cells were distributed in scaffolds. After 7-day cell culture of cell-laden scaffolds with or without VEGF incorporation, enhanced HUVEC cell proliferation, as measured by MTT assay, was achieved in VEGF-incorporated scaffolds.
SUMMARY: GF-incorporated and cell-laden scaffolds could be made in a single process via concurrent emulsion electrospinning and cell electrospray. Emulsion electrospun scaffolds gave sustained VEGF release. A high cell viability of delivered cells was achieved. HUVEC cell proliferation was significantly enhanced in VEGF-containing scaffolds.
Hierarchical Silk-Based Laminates for Annulus Fibrosus Tissue Engineering
1Department of Biomedical Engineering, National University of Singapore, Singapore
2 Department of Orthopedic Surgery, National University of Singapore, Singapore
3Department of Mechanical Engineering, National University of Singapore, Singapore
*Email: bietohsl@nus.edu.sg
Degeneration of the intervertebral disc (IVD) is one of the major causes of lower back pain. The IVD consists of the inner nucleus pulposus (NP) and outer annulus fibrosus (AF). During physiological loading, the AF withstands the bulging of the NP and keeps the structure of the IVD intact. In order to carry out such a function, the AF is highly hierarchical, consisting of multiple lamellae of aligned ECM fibres surrounding the NP. Silk is a highly versatile biomaterial with good mechanical properties and biocompatibility. Using electrospinning and layer-by-layer deposition techniques, we have demonstrated the ability to produce aligned nano-topographical cues using silk as the material of choice. We have also successfully further incorporated some of these nano-cues into silk-based hybrid laminates that can be used for eventual AF regeneration. The aim is to mimic the anatomic form of the AF with the use of these laminates that can be assembled to take the concentric form of the multi-lamellar AF in the native IVD. To mimic the tensile forces encountered by the native AF, a custom built bioreactor was further developed that is capable of mechanically stimulating such laminates to study the effects of mechanical stimulation. The AF is a difficult tissue to regenerate in part due to its complex architecture. Apart from having angled aligned fibres arranged in a concentric lamellae fashion, there is a gradual transition in ECM constituents and structure from the inner AF (mostly collagen Type II) to the outer AF (mostly collagen Type I). The incorporation of adipose-derived mesenchymal stem cells and cell-sheet engineering in conjunction with these silk-based hybrid laminates were further explored in this regards.
Poster Presentations (Even Numbers)
Preparation and Application of Nano Silica Grafted Low Molecular Weight Poly-3-hydroxybutyrate
Department of Chemical Engineering & Materials Science, Yuan-Ze University, Taiwan
Email: cesghong@saturn.yzu.edu.tw
Abstract is not available online
Synthesis and Physical Property of High Molecular Weight Vanillin-based Polyester
Bioplastic Research Team, Biomass Engineering Program Cooperation Division, RIKEN Center for Sustainable Resource Science,
2-1 Hirosawa, Wako, Saitama 351-0198, Japan
Email: koichiro.tachibana@riken.jp
INTRODUCTION: The utilization of lignin derivatives to polymeric materials has received much attention for sustainable polymer development and vanillin has been focused on in this area as a potential monomer due to its accessibility from lignin. Vanillin-based polyester will be used as engineering plastics due to their excellent thermal property. However, little attention has been paid on the physical properties as well as the production of high molecular weight polymer. Our research focuses on investigation of physical property of the high molecular weight vanillin-based polyester.
METHODS: 4-(3-Hydroxypropoxy)-3-methoxybenzoic acid (VaC3) was used as a monomer. Two-stages polycondensation procedure was conducted for the synthesis of high molecular weight poly (VaC3), (polypropylenevanillate, PPV). Physical property of the PPV was investigated using a PPV film fabricated by hot-pressing method. In addition, the film was oriented using a uniaxial drawing machine at 70 °C. Relation between orientation ratio and physical property was studied by tensile test, DSC and XRD.
RESULTS: Optimization of the reaction condition enabled to increase molecular weight of PPV over Mw 50 kg/mol. An increasing Mw enhanced tensile strength of PPV as well as processability in melt. Furthermore, orientation of PPV film allowed to enhance tensile property, for instance 120 MPa of tensile strength and 4.3 GPa of Young's modulus were reached after 9 times orientation. Birefringence value was increased with an increasing orientation ratio, although no significant diffraction pattern was found in XRD measurement.
DISCUSSION: Melt-state polycondensation under mild condition gave high Mw polymer due to prevention of thermal decomposition during the polymerization. The enhancement of tensile property after orientation of the PPV film might be explained by the presence of meso-phase, rigid amorphous, in the oriented PPV film.
Production of Carboxy-Terminal Modified Polyhydroxyalkanoate(PHA) via Alcoholysis Reaction Catalyzed by PHA synthase from Bacillus
1Department of Innovative and Engineered Materials, Tokyo Institute of Technology, Japan
2Biomass Engineering Program Cooperation Division, RIKEN Center for Sustainable Resource Science, Japan
3Department of Biological and Chemical Systems Engineering, Kumamoto National College of Technology, Japan
4Department of Materials Science and Chemical Engineering, Kitakyushu National College of Technology, Japan
*Email: manami.hyakutake@riken.jp
INTRODUCTION: Recently, PHAs have attracted attention as a potential alternative to petroleum-based plastics due to their biodegradability, biocompatibility, and thermoplasticity. However, for PHA biosynthesis, regulation of the end structure has not been developed for use as terminal modification. Regulating the terminal structure of polymers is beneficial for the synthesis of sequence- and structure-controlled copolymers. The aim of this study was to produce carboxy-terminal modified PHA via alcoholysis reaction catalyzed by PHA synthase from Bacillus cereus YB-4 (PhaRCYB4).
METHODS: First, the range of alcohol species available for alcoholysis reaction catalyzed by PhaRCYB4 was evaluated via PHA molecular weight changes during the second step of a two-step culture. For the two-step culture, Escherichia coli JM109 was used as a host strain, and each alcohol was added to the medium at the start of the second step. For one-step production of carboxy-terminal modified PHA, E. coli XL1-Blue was used as a host strain. PHA terminal structure was confirmed by NMR analysis.
RESULTS: When linear alcohols and PEGs were added to the medium, molecular weight decrease was observed. This result indicated that PhaRCYB4 utilized these alcohols for alcoholysis reaction. In addition, bifunctional compounds such as 2-propyn-1-ol were also available. NMR analysis showed that PHA carboxy-teminal was capped by each alcohol. Furthermore, recombinant E. coli XL1-Blue produced PHA with high modification yield through one-step cultivation.
DISCUSSION: It was demonstrated that PhaRCYB4 could utilize various types of alcohol. Through the use of bifunctional compounds for alcoholysis, the PHA carboxy terminus could be modified with thiol, alkynyl, hydroxy, and benzyl groups, resulting in the functionalization of the PHA carboxy terminus. In addition, modified PHA could be produced through one-step cultivation using recombinant E. coli XL1-Blue.These results indicated that terminal structure modified PHAs could be produced via alcoholysis reaction catalyzed by PhaRCYB4.
Degradation of Thermal and Digestion for Bacterial Poly(3-hydroxybutyrate)
Department of Chemical Engineering and Materials Science, Yuan Ze University, 32003, Taiwan
Email: cehswu@saturn.yzu.edu.tw
Abstract is not available online
Syntheses and optical properties of amorphous polysaccharide esters
1Graduate School of Agricultural and Life Sciences, The University of Tokyo, Japan
2School of Materials Science, JAIST, Japan
*Email: atiwata@mail.ecc.u-tokyo.ac.jp
INTRODUCTION: Glucomannan (GM) and pullulan (PL) are natural polysaccharides produced by plants or fungus. GM and PL are amorphous polymers with water solubility and biodegradability, and have high molecular weight (> 1.0×105). In this study, we have prepared thermoplasticized derivatives of GM and PL by esterification with carbonic acids, and their properties were investigated. In particular, optical properties of cast films of these polysaccharide esters were investigated in terms of optical transmittance and birefringence in comparison with cellulose triacetate (CTA) which are industrially applied as optical film.
METHODS: Glucomannan esters (GMEs) and pullulan esters (PLEs) with ester group carbon numbers of 2 or 3 were synthesized from GM and PL with carbonic acid and trifluoroacetic anhydride. The polysaccharide esters were characterized by 1H-NMR, GPC, TGA and DSC. Films of GMEs and PLEs were prepared by solvent-casting, and optical transmittance and birefringence of the films were investigated by spectral transmittance analyzer and optical birefringence analyzer. In addition, uniaxial stretched films were prepared to study relationships between orientation birefringence of stretched films and degree of orientation of polymer chain measured by infrared dichroism.
RESULTS: Completely esterified GMEs and PLEs (degree of substitution = 3) were prepared. Transparent films were obtained by solvent-casting, showing more than 80 % optical transmittance in the visible light region. PLE films showed quite low birefringence compared with CTA and GME films while GME films showed similar or a little smaller birefringence than that of CTA. In regards to stretched films, PLE showed lower orientation birefringence and lower degree of orientation of sugar chain than CTA and GME.
DISCUSSION: PLE films showed desirable characteristics as low birefringence film, which is attributed to the short relaxation time of pullulan chain. Amorphous polysaccharide ester films showed specific optical properties in comparison with crystalline CTA films.
Synthesis and characterization of polymers from D-glucaric acid
1Department of Biomaterial Sciences, The University of Tokyo, Japan
2Ensuiko Sugar Refining Co. Ltd., Japan
Abstract is not available online
Novel Miscible Blends of Biodegradable Polymer and Natural Polyphenol
Materials Science and Engineering, Feng Chia University, Taiwan (R.O.C.)
Email: ltlee@fcu.edu.tw and leo.lee0129@gmail.com
Abstract is not available online
The Application of Wound Dressing from Plasma-Modified PHAs Biomaterials
1Biorefinery & Bioprocess Engineering Laboratory, Department of Chemical Engineering and Materials Science, Yuan Ze University, Taiwan
2Department of Fragrance and Cosmetic Science, Kaohsiung Medical University, Kaohsiung, Taiwan
*Email: lanchiwei@saturn.yzu.edu.tw
Abstract is not available online
Novel Nanofibrous Scaffolds Incorporated with Gold Nanoparticle-based Theranostics for Cancer Patients
Dept. of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong
* Email: memwang@hku.hk
INTRODUCTION: For many cancer patients, after surgical removal of the tumor, new tissues need to be formed at previous tumor sites. Tissue engineering is now shown to be a viable way for human body tissue regeneration. In scaffold-based tissue engineering, electrospun nanofibrous scaffolds have major advantages over scaffolds produced by many other methods. Among cancer sufferers, after cancer treatment, cancer recurrence is a major threat. Timely detection and effective treatment for cancer recurrence are thus very important. Theranostics are nanodevices that combine diagnostic and therapeutic functions for cancers. The present study developed novel electrospun scaffolds containing theranostics.
METHODS: For Au nanoparticle (AuNP)-based theranostics, folic acid-chitosan-capped gold nanoparticles (Au@CS-FA) were synthesized. These nanoparticles consisted of a highly branched AuNP core and a cross-linked CS-FA shell. Folic acid in CS-FA would provide high cancer cell targeting ability. Coaxial electrospraying was investigated for producing core-shell structured microspheres which would provide controlled delivery of theranostics from scaffolds. PLGA/PEG polymer blend formed the shell and Au@CS-FA in distilled water was the core in microspheres. The novel scaffolds were fabricated using dual-source dual-power electrospinning and electrospraying, with electrospinning forming PLGA scaffolds.
RESULTS: The core-shell structure was revealed under TEM for electrosprayed microspheres, with Au@CS-FA theranostics being contained in the core. SEM examination showed that these microspheres were randomly distributed in scaffolds. Raman spectra of Au@CS-FA nanoparticles demonstrated greatly enhanced SERS intensity, which is useful for early cancer detection. The encapsulated theranostics were released from microspheres when the polymer shell degraded. The degradation rate depended on its composition, increasing with an increase in PEG content. In vitro experiments revealed that released theranostics maintained targeting ability for cancer cells.
SUMMARY: Nanofibrous scaffolds with theranostics-containing microspheres could be successfully made through current electrospinning and coaxial electrospraying. AuNP-based theranostics maintained in vitro cell targeting ability after their release from microspheres.
Substrate Specificity Analysis of Poly(lactate-co-3-hydroxybutyrate) Depolymerase from Variovorax sp. C34
1Graduate School of Engineering, Hokkaido University, Japan
2Department of Innovative and Engineering Materials, Tokyo Institute of Technology, Japan
3RIKEN-CSRS, Japan
4JST-CREST, Japan
*Email: staguchi@eng.hokudai.ac.jp
INTRODUCTION: Poly[(R)-lactate(LA)-co-(R)-3-hydroxybutyrate(3HB)] [P(LA-co-3HB)] is an unusual bacterial polyester produced by the engineered Escherichia coli. The homopolymer P(3HB) is known as natural biodegradable polymer. However, the biodegradability of the copolymer has not been evaluated. To address this problem, firstly, we attempted isolation of P(LA-co-3HB)-degrading bacteria and characterization of the depolymerase contributing to the degradation.
METHODS and RESULTS: We performed screening of P(LA-co-3HB)-degrading bacteria using the soil sample collected from the campus of Hokkaido University, and isolated a bacterium Variovorax sp. C34. A depolymerase PhaZVs secreted by Variovorax sp. C34 exhibited the activity to decrease the turbidity of the emulsions of P(67 mol% LA-co-3HB) and P(3HB), while a well studied P(3HB) depolymerase from Alcaligenes faecalis T1 (PhaZAf) had activity only toward P(3HB). This result suggested that the newly found P(LA-co-3HB) depolymerase possessed characteristic substrate specificity. The mechanism of degradation was studied by investigating the PhaZVs-mediated degradation products of P(3HB) and P(LA-co-3HB) within size exclusion chromatography, ESI-MS, and NMR. The P(3HB) degradation products were 3HB monomer and dimer, which were the same as those of previously reported P(3HB) depolymerases, indicating that trimer is the minimum substrate that recognized by PhaZVs. In the case of P(67 mol% LA-co-3HB), the degradation products consisted of LA and 3HB monomers, and LA-LA, 3HB-3HB, LA-3HB and/or 3HB-LA dimmers. This result indicated that PhaZVs hydrolyzed the ester bonds between LA and 3HB and between LA and LA units. The substrate specificity of PhaZVs was further confirmed by the hydrolysis of synthetic trimers of LA and 3HB. As the conclusion, P(LA-co-3HB) was degraded by PhaZVs via its broad substrate specificity toward every pattern of ester bonds that exist in the LA-incorporated copolymer. Considering the fact that the PhaZVs does not degrade PDLA, the hydrolysis of LA-LA linkage would depend on the length of the LA-clustering sequence.
Substrate Specificity Analysis of Poly(lactate-co-3-hydroxybutyrate) Depolymerase from Variovorax sp. C34
1Graduate School of Engineering, Hokkaido University, Japan
2Department of Innovative and Engineering Materials, Tokyo Institute of Technology, Japan
3RIKEN-CSRS, Japan
4JST-CREST, Japan
*Email: staguchi@eng.hokudai.ac.jp
INTRODUCTION: Poly[(R)-lactate(LA)-co-(R)-3-hydroxybutyrate(3HB)] [P(LA-co-3HB)] is an unusual bacterial polyester produced by the engineered Escherichia coli. The homopolymer P(3HB) is known as natural biodegradable polymer. However, the biodegradability of the copolymer has not been evaluated. To address this problem, firstly, we attempted isolation of P(LA-co-3HB)-degrading bacteria and characterization of the depolymerase contributing to the degradation.
METHODS and RESULTS: We performed screening of P(LA-co-3HB)-degrading bacteria using the soil sample collected from the campus of Hokkaido University, and isolated a bacterium Variovorax sp. C34. A depolymerase PhaZVs secreted by Variovorax sp. C34 exhibited the activity to decrease the turbidity of the emulsions of P(67 mol% LA-co-3HB) and P(3HB), while a well studied P(3HB) depolymerase from Alcaligenes faecalis T1 (PhaZAf) had activity only toward P(3HB). This result suggested that the newly found P(LA-co-3HB) depolymerase possessed characteristic substrate specificity. The mechanism of degradation was studied by investigating the PhaZVs-mediated degradation products of P(3HB) and P(LA-co-3HB) within size exclusion chromatography, ESI-MS, and NMR. The P(3HB) degradation products were 3HB monomer and dimer, which were the same as those of previously reported P(3HB) depolymerases, indicating that trimer is the minimum substrate that recognized by PhaZVs. In the case of P(67 mol% LA-co-3HB), the degradation products consisted of LA and 3HB monomers, and LA-LA, 3HB-3HB, LA-3HB and/or 3HB-LA dimmers. This result indicated that PhaZVs hydrolyzed the ester bonds between LA and 3HB and between LA and LA units. The substrate specificity of PhaZVs was further confirmed by the hydrolysis of synthetic trimers of LA and 3HB. As the conclusion, P(LA-co-3HB) was degraded by PhaZVs via its broad substrate specificity toward every pattern of ester bonds that exist in the LA-incorporated copolymer. Considering the fact that the PhaZVs does not degrade PDLA, the hydrolysis of LA-LA linkage would depend on the length of the LA-clustering sequence.
Using principles of nanotechnology to develop Hexapeptide hydrogels as potential drug delivery Systems and for tissue engineering applications
School of Chemical and Materials Engineering,
National University of Science and Technology, H-12 Islamabad, Pakistan
Email: khazima_nse01@scme.nust.edu.pk
INTRODUCTION: Self-assembling peptide hydrogels have emerged as a powerful and innovative product of nanobiotechnology. Due to their desirable physicochemical properties self-assembling peptides have found myriad of applications in the field of biotechnology and biomedicines. Previously self-assembling peptide sequence containing 8- 20 amino acid residues have been characterized and tested for their potential biological applications but now scientists are looking for ways to add cost effectiveness and vital tailorable properties to construct next generation of biomaterials.
METHODS: Experimentation process had been designed in such a way that factors influencing self-assembling process such as hydrophobicity, ionic concentration, concentration of peptide could be investigated. Fourier transform infrared (FTIR) and Scanning Electron Microscope (SEM) were the techniques used for analysis of structural and topographical properties of formed hydrogels respectively. From the results of above mentioned experiments most feasible biological application of self-assembling system was suggested e.g. drug delivery and tissue engineering. In this experimental work two different hexapeptides sequences were designed and purchased for analysis these hexapeptides were referred as P1 and P2.
RESULTS: Molecular arrangement of both P1 and P2 hexapeptide was a stable β sheet as depicted by FTIR spectral peak obtained at 1638 cm-1 wavelength. Change in pH did not influence the structural arrangement of self-assembling hydrogels. However difference was assessed as P1 hexapeptide hydrogel remained unaltered by change in pH while gelation kinetics of P2 reveals "pH responsive" nature of hexapeptide used. Morphological analysis of nanofibers uncovers a dense, interconnected fibril formation for both peptide based hydrogels.
DISCUSSION: These results indicate inherent stimulus responsive nature of P2 hydrogel thereby making it a potent drug delivery soft material while p1 hydrogel was considered suitable for tissue engineering purposes as it maintained its fibrous nature from pH1-pH7.In this research significance of nanotopographical features and cost effectiveness was valued as core asset.
Poster Presentations (Odd Numbers)
Preparation and Characterization of A Transparent Amorphous Cellulose Film
Department of Applied Chemistry, Graduate School of Engineering, Osaka University, Japan
E-mail: uyama@chem.eng.osaka-u.ac.jp
INTRODUCTION: Most cellulose films reported to date possess the crystalline structure with cellulose II, since it is thermodynamically more stable than other allomorphs. In contrast, amorphous cellulose film (ACF) with good performance has rarely been reported. In this research, a transparent amorphous cellulose film (ACF) was prepared from a cellulose solution of lithium chloride (8 wt%)/N,N-dimethylacetamide by regeneration with acetone.
METHODS: Typically, cellulose powder was first swollen in water, subsequently was washed by methanol and DMAc, then was dissolved in LiCl-DMAc at room temperature under nitrogen. Afterwards, the cellulose solution was centrifuged and casted on a glass plate, followed by regeneration from poor solvent. The regenerated cellulose gel was washed with water and dried at 40 °C for 2h in an air forced oven. Then, a transparent cellulose film was obtained and continually dried in a desiccator containing phosphorus pentaoxide at RT for at least 48 h.
RESULTS: The cellulose films, from four kinds of cellulose samples with different fiber length, showed highly amorphous structure, which was confirmed by X-ray diffraction, solid-state 13C-NMR and Fourier transform infrared (FT-IR) spectra. Tensile analysis implied that the elongation at break (23.9%) and maximum stress (157 MPa) of ACF that derived from Whatman CF11 fibrous cellulose (CF11) were a little higher than those of commercially available cellophane (19.9% and 135 MPa, respectively). In addition, enzymatic hydrolysis of ACF and cellophane showed much higher hydrolysis rate of the former (about 7 times higher than the latter).
DISCUSSION: It is believed that the regeneration solvent and drying process lead to the formation of ACF. The ACF possesses outstanding environmental friendliness, and would become a promising packaging material.
Crystallization behavior and the structural properties of Poly (1, 4-cyclohexanedimethlene terephthalate) containing Isosorbide
Department of Organic Nano Engineering, Hanyang University, Seoul, Korea
*Email: imss007@hanyang.ac.kr
Abstract is not available online
Synthesis of Epoxidized Plant Oil/Kenaf Fiber Composites
Department of Applied Chemistry, Graduate School of Engineering, Osaka University, Japan
**Email: uyama@chem.eng.osaka-u.ac.jp
Abstract is not available online
Development of Bio-based Acrylic Resins from the Non-edible Biomass
Bioplastic Research Team, Biomass Engineering Cooperation Division,
RIKEN Center for Sustainable Resource Science, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
Email: yasumasa.takenaka@riken.jp
INTRODUCTION: We focus on the development of new high-quality bio-based plastic materials from bio-based polymers and bio-based monomers. In addition, we aim to construct high efficient chemical recycling system of bio-based materials by using catalyst. Herein, we demonstrate the synthetic procedure of new type of bio-based acrylic resin such as poly(alkyl ctrotonate) from bio-synthesized poly(3-hydroxybutyrate) (P3HB) as the non-edible biomass. And also, we will show the physical and chemical properties of the obtained bio-based poly(alkyl ctrotonate).
METHODS: Bio-synthesized P3HB was obtained from Imperial Chemical Industries (ICI). Bio-based crotonic acid was prepared from bio-synthesized P3HB as the non-edible biomass according to the literature. Bio-based alkyl crotonate was given in high yield by the esterification of the prepared bio-based crotonic acid with alcohol. The group transfer polymerization (GTP) of alkyl crtonate was carried out under a dry and inert argon atmosphere in Schlenk equipments. The obtained bio-based poly(alkyl ctrotonate) was characterized by NMR, GPC, DSC, and TG-DTA analysis.
RESULTS: Bio-based crotonic acid was given in low yield as white crystalline powder by the pyrolysis of bio-synthesized P3HB using magnesium hydroxide catalyst. It was shown that the selectivity of trans-crotonic acid in this reaction was 86% by the 1H NMR analysis. When ethanol was used as an alcohol for the esterification of bio-based crotonic acid, bio-based ethyl crotonate was given in quantitative yield.
DISCUSSION: When an autoclave as a reactor was used in the pyrolysis of bio-synthesized P3HB, the selective transformation of P3HB into trans-crotonic acid by thermal degradation was lower than that of Nishida's previous report. However, these results indicate that it can be obtained the bio-based acrylic monomer from the non-edible biomass. Previously, we found that trans-crotonate was polymerized by group transfer polymerization using organic acid catalyst. Herein, we will show the development of bio-based acrylic resins from non-edible biomass as using these synthetic procedures.
Biosynthesis and Thermal Analysis of Poly(3-Hydroxybutyrate-co-3-Hydroxy-2-Methylbutyrate)
1Department of Innovative and Engineered Materials, Tokyo Institute of Technology, Japan
2Tokyo Metropolitan Industrial Technology Research Institute, Japan
Email: furutate.s.aa@m.titech.ac.jp
INTRODUCTION: Polyhydroxyalkanoates (PHA) are the carbon-renewable and the biodegradable materials and receive a lot of attention as an environmentally preferable thermoplastics. 3- Hydroxy-2-methylbutyrate (3H2MB) unit has been reported as a minor component of polyhydroxyalkanoate that synthesized by heterotrophic bacteria living in activated sludge. In this study, we found that PHA synthase (PhaCAc) derived from Aeromonas caviae is capable of polymerizing 3H2MB unit, and the thermal property of P(3HB-co-3H2MB) was evaluated.
METHOD: By feeding tiglic acid as 3H2MB precursor to Escherichia coli LS5218 or LSBJ expressing PhaCAc, PHA copolymer consisting of 3-hydroxybutyrate (3HB) and 3H2MB, P(3HB-co -3H2MB) was synthesized with 3H2MB fraction over 37mol%. These novel copolymers were characterized in the thermal property by DSC.
RESULTS: The 3H2MB incorporation into P(3HB) sequence led to reduction in glass transition temperature (Tg), melting temperature (Tm), and melting enthalpy (ΔHm). In contrast, unlike other PHA copolymers, cold crystallization temperature (Tcc) of P(3HB-co-3H2MB) was decreased by introducing 7-23 mol% 3H2MB unit. In addition, the crystallization half times (t1/2) are also evaluated and P(3HB-co-3H2MB) with around 23 mol% 3H2MB unit exhibits the shortest crystallization half times. These results suggest that P(3HB-co-3H2MB) copolymers are easier to crystallize than P(3HB) and other PHA copolymers.
DISCUSSION: Thermoplastics with a lower melting point and a higher crystallization speed result in the better processability in the practical uses and it can save the energy during the manufactural process. 3H2MB is thus a promising monomer unit to provide new thermal properties of 3HB-based polymers.
Controlled Radical Polymerization of Polyphenol-Inspired Polymers and Their Antioxidant Properties
Institute of Industrial Science, The University of Tokyo, Japan
*Email: yoshie@iis.u-tokyo.ac.jp
Abstract is not available online
Cost-effective 3D Printing of Tissue Engineering Scaffolds
Dept. of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong
Email: memwang@hku.hk
INTRODUCTION: 3D printing has aroused great interest for fabricating tissue engineering scaffolds. However, most industrial 3D printers are very expensive and biomolecules directly incorporated in 3D-printed scaffolds cannot maintain their bioactivity. In this study, cost-effective 3D printing of tissue engineering scaffolds was investigated. The incorporation and release of biomolecules in 3D-printed scaffolds were also studied.
SACFFOLD FABRICATION: An inexpensive desktop 3D printer (Makerbot, USA) was employed, with modifications for scaffold production. A refrigeration stage (-40°C) was designed for the machine as the printing substrate. Water-in-oil emulsions made of rhBMP-2-containing deionized water, a surfactant and a polymer solution [P(DLLA-co-TMC)/chloroform] were formulated as "inks" for printing. When the "ink" passing through the printer nozzle touched the printing substrate, the as-printed emulsion pattern was frozen quickly, forming a solidified pattern. The scaffold could then be built up layer-by-layer. To fabricate scaffolds with interconnected pores, a sodium alginate solution was used to form the support. Immediately after 3D printing, scaffolds were freeze-dried to remove organic solvent. Scaffolds were subsequently rinsed in deionized water to remove the support. With another freeze-drying, usable scaffolds were finally made.
RESULTS: Well-patterned, good quality scaffolds could be constructed using the 3D printing technique. SEM examinations revealed scaffolds had a regular, porous structure (pore size: 5-20 μm, tunable). The compressive strength and modulus of scaffolds were 0.65-0.8 MPa and 6.2-7.5 MPa, respectively. As P(DLLA-co-TMC) was used as scaffold matrix, scaffolds also exhibited shape memory ability. Temporarily deformed scaffolds immersed in a 37°C water bath could go back to their original shape within 30s. Scaffolds showed a controlled release behavior for rhBMP-2, albeit with a small initial burst release, within a 21-day in vitro test period. After release tests, scaffolds still maintained their designed porous architecture.
SUMMARY: A cost-effective 3D printing process was established for tissue engineering scaffolds. A growth factor, i.e., biomolecules, could be incorporated in scaffolds in this process. Layer by layer, a designed pattern could be drawn and stacked up to make scaffolds. Regular pores could be formed in scaffolds. Scaffolds had sufficient mechanical properties, and controlled release of rhBMP-2 could be achieved.
Cloning and Heterologous Expression of a Novel Subgroup of Class IV PHA (Polyhydroxyalkanoate) Synthase Genes in the Genus Bacillus
1Department of Materials Science and Chemical Engineering, Kitakyushu National College of Technology, Japan
2Department of Innovative and Engineered Materials, Tokyo Institute of Technology, Japan
*Email: mizuno@kct.ac.jp
A novel subgroup of Class IV PHA synthase genes (phaR and phaC) was discovered by screening and phylogenetic analysis in the genus Bacillus. We isolated a PHA-producing Bacillus sp. 6HS85-4 from a lime stone cave and cloned its partial phaC gene, and discovered a new cluster of potential Bacillus synthases by homology search. The full length of PHA synthase genes (phaRC) were cloned from Bacillus pseudofirmus JCM9141 and bataviensis JCM21706T, and separately expressed in Escherichia coli JM109 with a plasmid pGEM''ABex harboring phaAB, required for PHA production in a naturally non-PHA producer. Both transformants accumulated poly(3-hydroxybutyrate)[P(3HB)] with about 5% of the dry-cell-weight. The newly discovered phaC and phaR were different in sequence and operon structure from any previously reported synthase. Homology of the synthase sequences to that of known Class IV synthases in Bacillus cereus and megaterium was low (<40% identities). A common operon structure was found in the new subgroup as phaRC, which was different from previously known Class IV operons (phaPQ or phaJPQ, and phaRBC).
Environmentally Degradable Bio-based Plastics from Renewable Itaconic acid and their Composites with Montmorillonite
1School of Material science, Japan Advanced Institute of Science and Technology, Japan
2JST, CREST, Tokyo102-0076, Japan
*Email: kaneko@jaist.ac.jp
INTRODUCTION: The development of high-performance, environmentally-degradable polymers usable as engineering plastics from renewable resources are significant for the establishment of a sustainable society. Conventional polyamides such as NylonTM account for a substantial percentage of engineering plastics. Then we focus on bioplastics NylonTM from widely-produced biomolecules such as itaconic acid which is derived from fermentation of glucose in the presence of Aspergillus terreus. An in-bulk polymerization of itaconic acid, which contains two carboxylic acid groups and vinylene moiety, salts with a series of diamine by a melt poly-condensation process generated bio-derived thermally stable polymers. The structure favors two step reaction of Michael addition/amidation with diamines to form N-substituted "cyclic amide".
METHODS: We prepared nylon/montmorillonite (MMT) nanocomposites formed by nanocoupling of itaconate-bioderived polyamide with MMT through nylon salt method, at 165-200 °C under agitation with 300 rpm for 22 hr and subsequent steps of deep freezing under liquid nitrogen. As a result of thermomechanical evaluation by various techniques such as TGA, DSC, TEM, FT-IR, WAXD and tensile testing.
RESULTS: It was found that the nanocomposites showed the high performance; glass transition temperature, Tg, and 10 % weight loss temperature, T10, ranged 70-80 °C and 400-430 °C respectively. The processed fibers showed tensile strength and Young's modulus ranged 2.2-5.5 GPa and 65-241 MPa, respectively.
DISCUSSION: In addition, the elongation at break was largely enhanced by composite formation of NaMMT to be 0-10 wt% and then strain energy attained to be 22 J/m3. On the other hand, the nanocomposites had less moisture absorbing capacity of 2.5-3.9 wt% than conventional polyamide such as PA6 or PA66. The resulting bio-derived composites showed degradable behaviors inside soil and under ultraviolet-irradiated in water were additionally found by photo-induced ring-opening reaction of the pyrrolidone ring to give hydrophilic side-chains of carboxylic acid.