PHA based Core Sheath Fibrous Structures for Healthcare Engineering

PHA是FDA批准的由细菌在营养限制条件下使用可再生碳源产生的聚合物。有两种类型的PHA（图1），短链长度PHA，scl-PHA，（C3-C5单元）如P（3 HB）和中链长度PHA，mcl-PHA，（C6-C16单元）如P（3 HO-co-3 HD）。PHA的降解产物比PLA和PLGA的酸性低得多，并且是天然代谢产物，因此PHA在性质上具有较低的炎症性和免疫原性。此外，PHA通过表面侵蚀降解，因此基于PHA的支架以受控的可预测方式降解，这与通过本体侵蚀降解的PLA和PLGA相比是一个很大的优势。使用PHA的另一个优点是其性质的调谐。通过在生产过程中改变细菌菌株/碳源/培养基组成/发酵条件，可以定制PHA单体含量以及因此它们的材料性质和降解性。聚合物纤维技术的一种相对新颖的技术是使用加压回转（PG）开发芯-鞘纤维。该技术允许在具有放大可能性（~4 kg h-1）的单步中生产芯鞘双组分聚合物纤维。多层纤维形成在薄的鞘可以包含功能聚合物和核心可以是一个更传统的强度轴承生物聚合物。有许多生物医学应用需要非织造纤维基片材/支架，如伤口愈合补片，心脏补片，骨膜置换，心脏瓣膜，疝网，尿失禁网，颌面部置换。在该项目中，将优化一系列基于PHA的芯鞘纤维片材的生产，并将确定其在各种应用中的用途，包括骨骼、皮肤和心脏TE。

PHAs are FDA approved polymers produced by bacteria under nutrient limiting conditions using renewable carbon sources. There are two types of PHAs (Figure 1), short chain length PHAs, scl-PHAs, (C3-C5 units) such as P(3HB) and medium chain length PHAs, mcl-PHAs, (C6-C16 units) such as P(3HO-co-3HD). The degradation products of PHAs are much less acidic than those of PLA and PLGA, and are natural metabolites, hence PHAs are less inflammatory and immunogenic in nature. Also, PHAs degrade by surface erosion and therefore PHA-based scaffolds degrade in a controlled predictable manner, a great advantage as compared to PLA and PLGA that degrade by bulk erosion. Another advantage of using PHAs is the tuneability of their properties. By varying the bacterial strain/carbon source/media composition/fermentation conditions during production, the PHA monomer content and consequently their material properties and degradability can be tailored. A relatively novel technology for polymer fibre technology is the development of core-sheath fibres using pressurised gyration (PG). This technology allows the production of core-sheath bicomponent polymer fibres in a single-step with scale-up possibilities (~4 kg h-1). Layered fibres are formed where the thin sheath can contain a functional polymer and the core can be a more traditional strength-bearing biopolymer.There are many biomedical applications that require non-woven fibre-based sheets/scaffolds such as wound healing patches, cardiac patches, periosteum replacements, heart valves, hernia meshes, meshes for urinary incontinence, maxillofacial replacements. In this project the production of a range of PHA-based core-sheath fibre sheets will be optimised and their use in a variety of applications, including bone, skin and cardiac TE will be established.