In the biological guess, the biological data of artificial composition are the earliest and most discussed, and there are bioceramics, inorganic materials, metals and alloys. During this period, the use of metal data was the earliest, and it has a history of hundreds of years. Hydroxyapatite is another kind of constitutive biological material which has been studied more recently. It is the main inorganic component of mammalian hard arrangement. Since Hideki Aoki of Japan and Jarcho of the United States succeeded in artificially composing hydroxyapatite in the 1970s, it has become a hot topic in the study of hard-arranged repair materials.
With the improvement of people's requirements on environmental protection, together with the biochemical requirements of biological data itself, natural and semi-natural biological data have received more and more attention. Natural biological data are natural data consisting of biological processes, such as shells, bones, teeth, silk, spider silk, wood, eggshells, skin, tendons, etc. Because biological data is composed of tens of millions of years of evolution, and simple because of its unique structure, natural biological data has many excellent inductive functions. Among these kinds of data, polylactic acid (PLA), which is a typical representative of natural data, has become the most active biological data in recent years because of its good function and the use characteristics of both bioengineering data and biomedical data.
聚乳酸(PLA) 聚乳酸是由生物发酵出产的乳酸经人工化学组成而得的聚合物，但仍保持着良好的生物相容性和生物可降解性。具有与聚酯相似的防渗透性，一起具有与聚苯乙烯相似的光泽度?清晰度和加工性。并供给了比聚烯烃更低温度的可热合性，可采用熔融加工技能，包括纺纱技能进行加工。因而聚乳酸能够被加工成各种包装用资料，像农业?建筑业用的塑料型材?薄膜，以及化工?纺织业用的无纺布?聚酯纤维等。而PLA的出产耗能只相当于传统石油化工产品的20%—50%，产生的二氧化碳气体则只为相应的50%。 除作为包装资料以外，PLA可成为这些药物包裹资料?安排工程资猜中的研讨热门之一。PLA可制成无毒并可进行细胞附着成长的安排工程支架资料，其支架内部可构成供细胞成长和运送养分的多孔结构，还可为支撑和辅导细胞成长供给合适的机械强度和几许形状。其缺陷是缺少与细胞选择性作用的能力。PLA在生物医用资猜中的使用是广泛的，可用于医用缝合线(无须拆线)，药物控释载体(减少给药次数和给药量)，骨科内固定资料(避免了二次手术)，安排工程支架等。
Polylactic acid (PLA) polylactic acid (PLA) is a polymer made from lactic acid produced by bio-fermentation and made up by artificial chemistry, but it still maintains good biocompatibility and biodegradability. It has the same anti-permeability as polyester, and the same gloss as polystyrene? Clarity and processability. It also provides thermal bondability at lower temperatures than polyolefins, which can be processed using melt processing skills, including spinning skills. As a result, PLA can be processed into various packaging materials, such as plastic profiles for agriculture, construction, film, non-woven fabrics and polyester fibers for chemical industry, textile industry and so on. The energy consumption of PLA production is only 20%-50% of that of traditional petrochemical products, while the carbon dioxide gas produced is only 50%. In addition to packaging information, PLA can become one of the hot topics in the research of drug package information? PLA can be made into non-toxic scaffolds for cell attachment and growth. The scaffolds can form porous structures for cell growth and nutrient transport, and provide suitable mechanical strength and shape for supporting and guiding cell growth. The defect is the lack of the ability to selectively interact with cells. PLA is widely used in biomedical guessing. It can be used in medical suture (without needing to remove sutures), drug controlled release carriers (to reduce the number of doses and doses), orthopaedic internal fixation data (to avoid secondary surgery), engineering stents and so on.
Compared with PLA and other biological data, PHA structure is diversified. By changing bacteria, feeding and fermentation process, the composition of PHA can be easily changed, and the functional diversity brought by the diversity of composition structure makes it have obvious advantages in use. According to the composition of PHA dividends, there are two categories: short-chain PHA (C3-C5) and MEDIUM-LONG-CHAIN PHA (C6-C14). In recent years, it has been reported that strains can form short-chain and MEDIUM-LONG-CHAIN copolyhydroxyalkanoacid esters. The production of PHA has gone through the first generation of PHA-polyhydroxybutyrate (PHB), the second generation of PHA-hydroxybutyrate copolyester (PHBV) and the third generation of PHA-hydroxybutyrate hexanoic acid copolyester (PGBHx), while the fourth generation of PHA-hydroxybutyrate hydroxybutyrate (decanoic acid) copolymer [PH-BO (PHBD)] is still in the stage of development. During this period, as the third generation of PHA, PHBHx was first produced on a large scale by Tsinghua University and its cooperative enterprises. Compared with the production process of traditional chemical plastics products, the production of PHA is a kind of production with low energy consumption and low carbon dioxide emission. Therefore, from the production process to the product about environmental protection is very beneficial.
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