Fabrication Of Silk Fibroin/Chitosan Composite Nanofibers For Tissue Engineering Of Skin

Tissue engineering is a newly emerging interdiscipline at the convergence of cell biology and material science. The objective of tissue engineering is to regenerate natural tissues from living cells to replace defective or lost tissues and organs. Its typical method is to produce synthetic tissues by incorporating isolated living cells into porous scaffolds and create conditions for cells to proliferate, organize and develop into the desired tissues or organs. The key and challenge for tissue engineering is how to create excellent artificial extra cellular matrix(ECMs). Here the manual ECMs are three-dimensional biomaterial scaffolds with excellent biocompatibility and porosity. The functions of biomaterial scaffolds act as analogues of the natural ECMs found in tissues, which provide information for cells expressing their functions, e.g. adhesion, proliferation, differentiation. Therefore, the aim for biomaterial scaffolds design is to mimic the natural ECMs on both the components and the microstructure.The native extracellular matrix is a molecular complex made up of proteins and polysaccharides and comprises 3-dimensional hierarchical fibrous structures of nanometer scale dimensions. From the point of view of mimic, electrospinning of biocompatible silk fibroin and chitosan blends was studied to biomimic the natural ECMs on both the components and the microstructure in this paper. In our study, silk fibroin(SF) and chitosan(CS) were prepared to electrospun nanofibrous scaffolds. The properties of the electrospun silk fibroin-chitosan nanofibres have also been investigated. Fiber diameter was investigated by scanning electron microscope (SEM) with ImageJ software. Fourier transform infrared spectroscopy (FTIR) of fibers has proved that there's no interactions after electrospinning between silk fibroin and chitosan. The X-ray diffraction (XRD) has shown silk fibroin, chitosan and their complex fibers give typical amorphous after electrospinn The electrospun silk fibroin-chitosan nanofibers are water soluble and do not keep the fiber form, which can limit its applications. In order to improve both water-resistant ability and mechanical properties of nanofibers, the fibrous membrane was crosslinked by glutaraldehyde (GTA) vapor and the time of crosslinking was 2 days. The properties of the crosslinked fibrous membrane were also investigated further. FTIR shows that crosslinking induce silk fibrion conformation from a-helix to 13-sheet. XRD analyses shows the crosslinked fibers still are amorphous. The average ultimate tensile strength of the silk fibrion-chitosan fibrous membrane has been enhanced, but the average ultimate tensile elongation of the fibrous membrane decreases.On the other hand, comprehensive characteristics of biosafty including attachment, spreading and proliferation of murine fibroblasts (L929) on electrospun nanofibrous mats were studied by SEM (3,000×), hematoxylin and eosin (HE) staining which demonstrate that the cells could function biologically on the nanofibrous membranes and nanofibrous structure is available for cell attachment. Dimethylthiazol diphenyltetrazolium bromide (MTT) assay, which illustrates fibroblast adhesion on the fibers is better than that on the cover slips. In addition, permeability, antibacterial activity, and animal test show the availability of silk fibroin/chitosan composite nanofibers in skin tissue engineering.In a word, electrospun silk fibroin-chitosan fibrous membrane is a promising biomedical material. The research will provide the data and the base for electrospun silk fibroin-chitosan fibrous membrane to be selected as skin tissue engineering scaffold in clinic.