Fabrication Of SF-PLGA Blend Nanofibers And Application In Neural Repair

Tissue engineering (TE) is one of the new subjects which combined Biology and Material Science. The basic concept of TE is aimed to reestablish human tissue and organs by planting the TE scaffolds with functional cells incorporated into the damaged position. Therefore, the key point and the most challenged technique of TE are to fabricate the tissue engineering scaffolds which could mimic the natural extracellular matrix (ECM).Electrospinning is one of the effective methods to produce nanofibers with diameter ranging from several nanometers to hundreds of nanometers. Recently, electrospinning of biopolymers attracts more attentions owing to their good biocompatibility. The electrospun nanofibers have many potential applications in tissue engineering.In this study, the PLGA/SF blended nanofibrous membranes with different weight ratios were fabricated using 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) as a solvent via electrospinng. The nanofibrous morphologies were observed by SEM, the results showed that the diameters of resuting nanofibers were affected by solution concentrations and the blend ratio. The water contact angles increased by decreasing the contents of SF. ATR-FTIR and XRD analyses demonstrated no obvious chemical bond reaction between SF and PLGA.The tensile strength and elongation at break of nanofibrous membrances increased with increasing content of PLGA. The unique aspect of the post-processing protocol in this study involves the use of methanol as the post-processing agent to enhance the water resisting property and stability. The nanofibrous morphologies were observed by SEM, the results showed that the nanofibers still maintained an excellent morphology after treated by methanol vapor. XRD analyses demonstrated that the crystallinity occured significant changes. Water contact angles of SF-PLGA decreased after treated, and also decreased while increasing the contents of SF. The tensile strength and elongation at break of post-processed nanofibrous membrances decreased compared with untreated mats except the pure SF mats. The tensile strength of the treated SF sample was increased, but the elongation at break was decreased. The blended nanofibers are potential for their application in tissue engineering scaffolds and to develop functional biomaterials.Schwann cells (SCs) were seeded onto nanofiber mats for adherence and proliferation studies. The cells had a good adherence on nanofibrous mats with SF-PLGA at different ratios, and the amount of the cells'proliferation was more than that of control group on the first day after seeding. SEM images showed that cells maintained good shape on nanofibrous mats. These results demonstrated that treated SF-PLGA nanofibrous scaffolds showed no cytotoxicity toward cell growth with good biocompatibility in vitro.In vitro degradation of SF-PLGA nanofibrous scaffolds were carried out in phosphate buffered saline (7.4±0.1) at 37℃for 6 months. Through a series of analysis and characterization(including loss weight, pH changes of PBS solutions) to fiberous scaffolds after degradation for different time, the results showed that the pure SF nanofibrous scaffolds were not degradable in PBS, the degradation rate of the SF-PLGA(2:8) fibrous scaffolds were faster than others. The adding of SF accelerated the degradation rate of PLGA.Aligned nanofibrous scaffolds of SF-PLGA(2:8) were fabricated by electrospinning technique under optimum condition. The degree of orientation increased with the increase in the rotating drum rates from 500 to 4000rpm. MTT results showed Schwann cells(SCs) had greater proliferation on random/aligner SF-PLGA nanofibrous scaffolds than that on random/aligned PLGA fibrous scaffolds. And SCs had greater proliferation on aligned SF-PLGA nanofibrous scaffolds than random SF-PLGA nanofibrous scaffolds. The alignment of the SF-PLGA nanofibers could control cell orientation and strengthen the interaction between the cell body and the fibers in the longitudinal directon of the fibers.Adult male Sprague-Dawley (SD) rats were used for animal models. The aligned SF-PLGA(2:8) nanofibrous nerve guidance conduit (NGC) was used for bridge implantation across a 10-mm long sciatic nerve defect in rats, PLGA nanofibrous nerve guidance conduit and nerve autografts were used control. The outcome of regenerated nerve at 12 weeks was evaluated by a combination of histological and electron microscopy study.