推动聚乳酸材料的应用 构建L-乳酸、聚乳酸生物材料产业链

生物降解材料——聚乳酸的应用前景广阔,构建我国L-乳酸、聚乳酸生物基材料产业链的迫切性和必要性不言而喻。国家“十五”科技攻关计划课题“L-乳酸与聚乳酸技术”的研发成果表明：以农业经济作物为原料生产低成本L-乳酸、聚乳酸的工艺路线,以工业生物技术为手段可以为制造环境友好的生物降解材料、形成可持续发展的循环经济产业链提供技术支持。     

聚乳酸技术与市场现状及发展趋势分析

随着原料生产和制品加工技术的进步,生物降解材料备受关注,成为可持续、循环经济发展的焦点。聚乳酸是一种新兴的生物可降解材料,具有环境友好性、生物安全性等特点。从技术和市场两个角度,阐述了全球包括我国的聚乳酸技术和市场现状,并对聚乳酸的发展前景和趋势进行了分析。     

聚乳酸(PLA)生物降解的研究进展

聚乳酸(Polylactic Acid,PLA)是一种新兴的,由可再生资源--乳酸聚合而成的高分子聚酯.因为其具有优良的物理化学性能、生物相容性及生物可降解性,且对环境及人体无毒害作用,而被认为是一种最具潜力的绿色生物塑料.作为环境友好材料,聚乳酸日益受到人们的重视.基于可循环利用的考虑,其生物降解的研究也成为当前研究的一个重要方面.本文综述了PLA生物降解领域的相关进展,包括降解的微生物学、相关酶学及分子生物学,系统阐述了PLA可能的生物降解机制.并对生物系统处理PLA废弃物的可行性进行了探讨.     

聚乳酸成核剂研究进展

聚乳酸是以乳酸为原料而合成得到的一种高分子材料,具有良好生物相容性、可生物降解性。目前工业规模化生产的聚乳酸主要是以左旋乳酸合成得到的聚乳酸,制得的制品透明性好,但缺点是不能耐热。添加成核剂可以提高聚乳酸的结晶度,从而提高它的耐热性能。本文综述了有机成核剂和无机成核剂的研究进展。     

中粮集团加盟长春生物制造产业

<正>中粮集团在长春投资建设的3万吨聚乳酸原料、3万吨聚乳酸下游制品项目近日正式签约。吉林省是我国玉米主产区之一,中粮集团投资聚乳酸项目,有利于吉林省由玉米经济向生物质经济转变,加快把玉米资源优势转变为产业优势和经济优势。聚乳酸是从玉米、玉米秸秆等植物中提取淀粉,经微生物发酵乳酸后再聚合而成的一种高分子生物基材料。聚乳酸是生物降解材料的重要品种,是产业化最成熟、产量最大、应用最广泛的生物     

聚乳酸塑料合成、生物降解及其废弃物处置的研究进展

随着国内外禁塑令和限塑令的升级,以聚乳酸(polylactic acid, PLA)为代表的生物基塑料成为传统石油基塑料市场的主要替代品,备受产业界的青睐。然而,公众对生物基塑料的认识仍存在诸多误解。事实上,生物基塑料的降解需要在特定条件下才能实现,泄入到自然环境中同样难以降解,会对人体、生物多样性和生态系统功能造成危害,这与传统石油基塑料相似。近年来,随着我国PLA产能和市场规模不断的提高,亟需进一步加强对PLA等生物基塑料降解性能的认识,挖掘PLA生物降解资源,关注和研究生物基塑料回收处理模式。基于上述背景,本文首先介绍了PLA塑料的性质及合成方式,以及PLA塑料的产业化与市场规模;其次,对目前聚乳酸塑料微生物与酶法降解的研究进展进行了综述,并对其生物降解机制进行了探讨;最后,提出了微生物原位处理和酶法闭环回收两种聚乳酸塑料废弃物生物处置方法,并对PLA生物基塑料的发展前景和趋势进行了展望。     

聚乳酸的生物降解

聚乳酸(polylactic acid, PLA)因其良好的理化性能、生物相容性和生物降解性而备受关注，已被认为是石油基塑料最具潜力的替代者，但在实际应用中仍然存在降解缓慢循环周期长的问题，因此对PLA的生物降解深入研究对于解决塑料垃圾污染和缓解能源危机至关重要。近年来，有关微生物(放线菌、细菌和真菌)和酶(蛋白酶、脂肪酶、酯酶和角质酶)降解PLA的研究已经取得了一定的进展。本文从降解微生物、降解酶和降解机制等方面综述了PLA生物降解的研究进展，并展望了PLA生物降解研究未来的发展趋势。     

国内生物基材料产业发展现状

近年来,生物基材料正逐步成为引领当代世界科技创新和经济发展的又一新的主导产业。文章综述了国内生物基材料产业的最新进展,对整个生物基材料产业市场进行了综合分析,包括生物基化学品如乳酸、1,3-丙二醇、丁二酸等,可生物降解生物基塑料如二元酸二元醇共聚酯、聚乳酸、二氧化碳共聚物、聚羟基烷酸酯、聚己内酯、热塑性生物质塑料,非生物降解生物基塑料如生物基聚酰胺、聚对苯二甲酸丙二醇酯、生物基聚氨酯,以及生物基纤维等材料的产业现状。     

乳酸及聚乳酸的工业发展及市场前景

<正>乳酸广泛应用于食品、饮料、医药、化妆品等领域。2014年除聚乳酸以外的全球乳酸市场约为35万~40万吨,年增长率约10%。中国国内乳酸市场约为7万~8万吨,年出口量约4万~5万吨,但产能已超过20万吨,远非传统乳酸市场所能消化,也大大超前于聚乳酸工业的发展,但许多新公司仍竞相建厂。近年来,生物基聚合物尤其是可完全生物降解且健康安全的聚乳酸材料备受关注。2014年中国聚乳酸市场约为1万~2万吨,主要为加工出口,全     

产业动向

我国首支人用禽流感疫苗获药品批号；我国聚乳酸树脂实现规模产业化;世界最大半合成抗生素项目投产;法国开发出新型可生物降解／堆肥的薄膜;中科院泰州研发与产业化中心增加新成员机构     

Biodegradable semipermeable microcapsules containing enzymes, hormones, vaccines, and other biologicals.

Semipermeable microcapsules were prepared using biodegradable material as the enclosing membranes. For instance, polylactic acid was used as membrane material to microencapsulate biologically active materials. Asparaginase microencapsulated within polylactic acids functions effectively in converting external asparagine into aspartic acid and ammonium. By variations in permeability characteristics, insulin microencapsulated within polylactic acid can be released at pre-adjusted rates. Thus, release rates of 50% in 5 hours, 50% in 20 hours, and 2.5% in 24 hours have been demonstrated. Drugs and vaccines have also been similarily microencapsulated. The advantage of the biodegradable microcapsules is the ability of the body to convert the injected polymer material to normal body metabolites (e.g., CO2 and H2O in the case of polylactic acid) after completion of its function.     

Lipase-catalysed polymerization of lactic acid and its film forming properties

Extensive studies on lipase-catalysed preparation of polylactic acid showed that porcine pancreatic lipase (PPL) showed better conversions of lactic acid monomer and higher molecular weight polylactates than those with lipozyme IM20. Molecular weight determined by end group analysis showed that the highest molecular weight achieved was 1423 at 80.2% conversion by PPL. Employment of dicarboxylic acids or their anhydrides at 0.1–1.0 molar equivalents as linker molecules along with polylactic acids prepared as mentioned above resulted in still higher molecular weight polymers. The highest yield of 80.1% with a molecular weight of 3300 was achieved with 0.1 molar equivalent of succinic anhydride. Blends of enzymatically prepared polylactic acids with polystyrene yielded very good films in terms of tensile strength, elongation and optical properties.     

Novel CaO/polylactic acid nanoscaffold as dental resin nanocomposites and the investigation of physicochemical properties

In this study, for the first time, calcium oxide (CaO)/polylactic acid nanoscaffolds were synthesized by co‐precipitation assistant reverse micelles method. The physical and chemical (physicochemical) properties of the structures as dental resin composites were also studied. Nanocomposite materials as primary and basic dental compounds can be conveniently applied as dental filling materials with a high esthetic quality. In this research nanoscaffolds act as a bed for nanoparticles and improve the mechanical and chemical (mechanochemical) properties, CaO nanoparticles were loading in polylactic acid nanoscaffold as a bioactivity polymer for usage in the dental resin composites. Mechanical properties of the dental resin composite containing CaO/polylactic acid nanoscaffold were calculated: the flexural strength (137.2 MPa), modulus (12.9GPa) and compressive strength (344.2 MPa). Potential of the basic nanoparticle and the products were characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), dynamic light scattering (DLS), ultraviolet‐visible spectroscopy (UV‐visible) and atomic force microscopy (AFM) showed the size of the optimized nanostructures was about 85 to 120 nm. According to TGA results of polylactic acid nanofibers with thermal stability below 300°C these high thermal stability materials can be used as dental resin composites.     

生物基乳酸生物转化研究进展

乳酸的发酵生产技术已取得了长足的进步,作为一种重要生物基化学品,乳酸除了可用于食品工业及生产聚乳酸外,亦可作为一种重要的平台化合物,用于生产丙烯酸、丙酮酸、1,2-丙二醇、乳酸酯等。文中重点综述了以生物基乳酸为原料经脱水、脱氢、还原及酯化反应生产乳酸衍生物的生物转化工艺,对该领域的发展趋势进行了展望。     

Biodegradable plastics from renewable sources

Plastic waste disposal is a huge ecotechnological problem and one of the approaches to solving this problem is the development of biodegradable plastics. This review summarizes data on their use, biodegradability, commercial reliability and production from renewable resources. Some commercially successful biodegradable plastics are based on chemical synthesis (i.e. polyglycolic acid, polylactic acid, polycaprolactone, and polyvinyl alcohol). Others are products of microbial fermentations (i.e. polyesters and neutral polysaccharides) or are prepared from chemically modified natural products (e.g., starch, cellulose, chitin or soy protein).     

Engineered myocardial tissues constructed <Emphasis Type="Italic">in vivo</Emphasis> using cardiomyocyte-like cells derived from bone marrow mesenchymal stem cells in rats

Background  

To explore the feasibility of constructing engineered myocardial tissues (EMTs) in vivo, using polylactic acid -co-glycolic acid (PLGA) for scaffold and cardiomyocyte-like cells derived from bone marrow mesenchymal stem cells (BMMSCs) for seeded cells.     

Prefabrication of bone by use of a vascularized periosteal flap and bone morphogenetic protein.

The purpose of this pilot study was to prefabricate a vascularized bone graft by using a vascularized periosteal flap containing osteoprogenitor cells, a structural matrix, and recombinant human bone morphogenetic protein-2 (rhBMP-2). In a rat model, a periosteal flap vascularized by the saphenous artery and vein was dissected off the medial surface of the tibia. This flap consisted of three layers-periosteum, muscle, and fascia-and was tubed on itself to form a watertight chamber that was then transferred on its vascular pedicle to the groin. A total of 78 vascularized periosteal chambers were constructed in 39 animals and divided into 10 groups. In group 1, the periosteal chamber was left empty. Groups 2, 3, and 4 consisted of the periosteal flap and rhBMP-2, but in group 3, the proximal vascular pedicle was ligated, and in group 4, the flap was harvested without the periosteal layer and turned inside out. Groups 5 through 10 consisted of the vascularized periosteal flap containing several different structural matrices (calcium alginate spheres, polylactic acid, or demineralized bone matrix) with or without rhBMP-2. Animals were killed at 2, 4, or 8 weeks in each group. The presence and density of any new bone formation was evaluated both radiologically and histologically. Significant bone formation was seen only in those periosteal flaps containing rhBMP-2 and either the calcium alginate or polylactic acid matrix. New bone formation increased both radiologically and histologically from 2 weeks to 8 weeks only in the periosteal flaps containing the polylactic acid matrix and rhBMP-2. This preliminary study therefore suggests that four factors-blood supply, osteoprogenitor cells in the periosteal layer, a biodegradable matrix, and rhBMP-2-are required for optimal prefabrication of a vascularized bone graft.     

Cutinase-like enzyme from the yeast Cryptococcus sp. strain S-2 hydrolyzes polylactic acid and other biodegradable plastics

A purified lipase from the yeast Cryptococcus sp. strain S-2 exhibited remote homology to proteins belonging to the cutinase family rather than to lipases. This enzyme could effectively degrade the high-molecular-weight compound polylactic acid, as well as other biodegradable plastics, including polybutylene succinate, poly (epsilon-caprolactone), and poly(3-hydroxybutyrate).