Study On Preparation And Characterization Of A Electrospun Spider Silk Fibroin/Poly(D, L-Lactide) Composite Fibers

In this thesis, a significant research on the Electrospun Spider Silk Fibroin/poly(D,L-lactide) Composite Fiber for a tissue engineering scaffold has been carried out as to the deficiency of hydrophilia and mechanical property of PDLLA. The biodegradable polymer PDLLA, which was nontoxicity and biocompatible, was chosed in the present study. As the blending, spider silk has advantages of excellent mechanical property, better biocompatibility and cellular affinity. Based on those advantages, the scaffold might have a potential effect in the treatment of defective incomplete tissue in the future.Firstly, we successfully prepared electrospun spider silk fibroin/poly(D,L-lactide) composite fibers by electrospinning. Characteristics of the composite fibrous nonwoven mats were observed by scanning electron microscope (SEM), transmission electron microscope (TEM), fourier transform infrared (FTIR), differential scanning calorimetry (DSC), contact angle equipment (CA) and universal testing machine. The results indicated that there was regular continuous spidroin fibrillar structure in composite fibers beyond the 15% ratio of spidroin, and the average diameter of composite fibers with spidroin ratio of 25% was 216±54 nm. Compared to the original spidroin, it was showed that theβ-sheet structure of regenerated spidroin was increased distinctly, but helical conformation of the spidroin was increased after electrospinning. Moreover, the hydrophilia and mechanical property of PDLLA fibers could be improved evidently by introducing spidroin into it.Secondly, X-ray powder diffraction (XRD), TEM and FTIR were carried out to investigate the influence of the solution, an external electric field and a high pressure on crystallization and structure of spidroin. The results indicated that spidroin of spider silk fibroin/poly(D,L-lactide) composite film or electrospun composite fibers obtained by volatilizing solution slowly or fast under an external electric field, mainly adopted Spiderion I crystal form. And the crystal orientation of spidroin had an increase after the electrospun composite fibers were treated by a high-pressure.Finally, the vitro matrix degradation was carried out to investigate the degradation and its influence factors of electrospun composite fibers and PDLLA fibers. The degradation results show that there were the loss of fibrous nonwoven mats mass, the decrease of pH value of degradation medium, the change of fibrous nonwoven mats shape, and the reduction of polymer number-average molecular weight (Mn). In addition, the hydrophilia property of PDLLA fibers was improved evidently by introducing spidroin into them, which accelerated their degradation. Meanwhile, the cytotoxicity of electrospun fibrous nonwoven mats was evaluated. The results indicated that the cell proliferation on the electrospun composite fibrous nonwoven mats was normal, which was consequently suggested that they had little cytotoxicity.