Textile Technology Research Group, School of design, University of Leeds, UK.
Textile Technology Research Group, School of design, University of Leeds, UK; Biomaterials and Tissue Engineering Research Group, School of Dentistry, St. James's University Hospital, University of Leeds, UK.
Mater Sci Eng C Mater Biol Appl. 2018 Oct 1;91:541-555. doi: 10.1016/j.msec.2018.05.076. Epub 2018 May 28.
Electrospun nanofibrous membranes of natural polymers, such as gelatin, are fundamental in the design of regenerative devices. Crosslinking of electrospun fibres from gelatin is required to prevent dissolution in water, to retain the original nanofibre morphology after immersion in water, and to improve the thermal and mechanical properties, although this is still challenging to accomplish in a controlled fashion. In this study, we have investigated the scalable manufacture and structural stability in aqueous environment of a UV-cured nanofibrous membrane fabricated by free surface electrospinning (FSES) of aqueous solutions containing vinylbenzylated gelatin and poly(ɛ-caprolactone) dimethacrylate (PCL-DMA). Vinylbenzylated gelatin was obtained via chemical functionalisation with photopolymerisable 4-vinylbenzyl chloride (4VBC) groups, so that the gelatin and PCL phase in electrospun fibres were integrated in a covalent UV-cured co-network at the molecular scale, rather than being simply physically mixed. Aqueous solutions of acetic acid (90 vol%) were employed at room temperature to dissolve gelatin-4VBC (G-4VBC) and PCL-DMA with two molar ratios between 4VBC and DMA functions, whilst viscosity, surface tension and electrical conductivity of resulting electrospinning solutions were characterised. Following successful FSES, electrospun nanofibrous samples were UV-cured using Irgacure I2959 as radical photo-initiator and 1-Heptanol as water-immiscible photo-initiator carrier, resulting in the formation of a water-insoluble, gelatin/PCL covalent co-network. Scanning electron microscopy (SEM), attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, differential scanning calorimetry (DSC), tensile test, as well as liquid contact angle and swelling measurements were carried out to explore the surface morphology, chemical composition, thermal and mechanical properties, wettability and water holding capacity of the nanofibrous membranes, respectively. UV-cured nanofibrous membranes did not dissolve in water and showed enhanced thermal and mechanical properties, with respect to as-spun samples, indicating the effectiveness of the photo-crosslinking reaction. In addition, UV-cured gelatin/PCL membranes displayed increased structural stability in water with respect to PCL-free samples and were highly tolerated by G292 osteosarcoma cells. These results therefore support the use of PCL-DMA as hydrophobic, biodegradable crosslinker and provide new insight on the scalable design of water-insoluble, mechanical-competent gelatin membranes for healthcare applications.
天然聚合物的静电纺纳米纤维膜，如明胶，是再生装置设计的基础。为了防止在水中溶解，为了在浸入水中后保持原始纳米纤维形态，以及为了改善热和机械性能，需要对明胶的静电纺纤维进行交联，尽管以可控的方式实现这一点仍然具有挑战性。在这项研究中，我们研究了通过自由表面静电纺丝（FSES）制造的 UV 固化纳米纤维膜的可扩展制造和在水环境中的结构稳定性，该膜由含有乙烯基苄基化明胶和聚（ε-己内酯）二甲基丙烯酸酯（PCL-DMA）的水溶液制成。乙烯基苄基化明胶是通过用可光聚合的 4-乙烯基苄基氯（4VBC）基团进行化学官能化获得的，因此明胶和 PCL 相在电纺纤维中以分子尺度整合在共价 UV 固化共网络中，而不是简单地物理混合。在室温下使用 90vol%的乙酸水溶液溶解明胶-4VBC（G-4VBC）和 PCL-DMA，其中 4VBC 和 DMA 功能之间存在两个摩尔比，同时对所得静电纺丝溶液的粘度、表面张力和电导率进行了表征。成功进行 FSES 后，使用 Irgacure I2959 作为自由基光引发剂和 1-庚醇作为不混水的光引发剂载体对静电纺纳米纤维样品进行 UV 固化，从而形成不溶于水的明胶/PCL 共价共网络。通过扫描电子显微镜（SEM）、衰减全反射傅里叶变换红外（ATR-FTIR）光谱、差示扫描量热法（DSC）、拉伸试验以及液体接触角和溶胀测量，分别研究了纳米纤维膜的表面形态、化学组成、热性能和机械性能、润湿性和保水性。与未固化的样品相比，UV 固化的纳米纤维膜在水中不溶解，表现出增强的热性能和机械性能，表明光交联反应的有效性。此外，与不含 PCL 的样品相比，UV 固化的明胶/PCL 膜在水中具有更高的结构稳定性，并且可以很好地耐受 G292 骨肉瘤细胞。因此，这些结果支持将 PCL-DMA 用作疏水性、可生物降解的交联剂，并为用于医疗保健应用的水溶性、机械性能良好的明胶膜的可扩展设计提供了新的见解。
