PHA based Core Sheath Fibrous Structures for Healthcare Engineering

PHA是FDA批准的聚合物，由细菌在营养限制条件下使用可再生碳源生产。有两种类型的PHA(图1)，短链长度的PHA，scl-PHA，(C3-C5单元)，如P(3HB)和中链长度的PHAs，MCL-PHAs，(C6-C16单元)，如P(3HO-co-3HD)。PHAs的降解产物比聚乳酸和PLGA的酸性小得多，是天然的代谢物，因此PHAs的炎性和免疫原性较小。此外，PHA通过表面侵蚀降解，因此PHA支架以可控的可预测方式降解，与通过本体侵蚀降解的聚乳酸和PLGA相比，这是一个巨大的优势。使用PHA的另一个优点是其性质的可调性。在生产过程中，通过改变菌种/碳源/基质组成/发酵条件，可以定制PHA单体含量，从而调整其材料特性和降解性。聚合物纤维技术的一项相对较新的技术是利用加压回转(PG)开发芯鞘纤维。这项技术允许一步生产具有放大能力(约4 kg h-1)的芯-鞘双组分聚合物纤维。层状纤维形成在薄鞘可以包含功能性聚合物而核心可以是更传统的承载强度的生物聚合物的地方。有许多生物医学应用需要基于非织造纤维的片材/支架，例如伤口愈合贴片、心脏贴片、骨膜置换、心脏瓣膜、疝气网片、尿失禁网片、颌面部置换。在这个项目中，将优化一系列基于PHA的芯鞘纤维板的生产，并建立它们在各种应用中的用途，包括骨、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.