Controllable Preparation Of Silk Fibroin-based Nanofibrous Membranes And Its Application In The Repair Of Skin Bruns

Electrospinning is a relatively easy technology for making continuous fibers with scalefrom sub-micron to nanometer. With the advantages of large specific surface area and highporosity, electrospinning nanofibrous membranes have a similar structure to natural extracellularmatrix, which are widely used in tissue engineering. Considering the demands of tissueengineering to the scaffold materials, it is better to choose the scaffold materials with excellentbiological compatibility, good mechanical properties and favorable biodegradability.In our investigation, the regenerated silk fibroin (SF) and gelatin (GE) were dissolved inhexafluoroisopropanol (HFIP) with different weight ratios and then were used to prepare theSF/GE blend nanofibrous membranes by electrospinning. Various characterizations, such asscanning electron microscope (SEM)、distribution of pore size analysis equipment (PSDA)、Fourier transform infrared spectroscopy (FTIR) and multi-purpose tensile test were employed toexplore the morphology、structure and mechanical properties of the SF/GE blend nanofibrousmembranes. The results indicated that with the increasing of GE, both of the average diameterand the pore size of the nanofibers increased gradually. Furthermore, the toughness of the blendnanofibrous membranes improved but the breaking strength decreased with the addition of GE.Considering the demands of good mechanical properties to the scaffold materials in tissueengineering, the SF/GE weight ratio was determined at75/25to make a further postprocessing ofthe blend nanofibrous membranes.In order to improve the water-stability of the electrospinning scaffold, the blend nanofibrousmembranes were cross-linked by the vapor of glutaraldehyde. The swelling behavior of the blendnanofibrous membranes after being cross-linked was investigated, and an appropriatecross-linking time was determined at48h. The mechanical testing indicated that the breakingstrength of the cross-linked blend nanofibrous membranes increased with the decrease of thetoughness.With the purpose of improving the mechanical properties of the fiber scaffolds to a certain extent, the shell (regenerated silk/gelatin)-core (poly (ε-caprolactone)) structured compositenanofibrous membranes were prepared by coaxial electrospinning. The concentrations of thecore materials have evident effects on the morphology、pore size and mechanical properties ofthe composite nanofibrous membranes, which were also discussed. The results implied that theSF/GE-PCL composite nanofibrous membranes prepared in this work have distinctive shell-corestructure and smooth surface. With the core concentration changing from4%to10%, theaverage diameter of the fibers increased from256nm to941nm, the average pore size of thenanofibrous membranes conversed from0.576μm to1.018μm, as well as the breaking strengthand breaking strain of the nanofibrous membranes increased. At the same time, from the X-raydiffraction (XRD) spectrum, it could be concluded that both of the process of coaxialelectrospinning and the concentrations of the core materials influence the crystal structure of thenanofibrous membranes.The MTT method is a commonly used process to evaluate the cytotoxicity. In the presentpaper, the cytotoxicity of the SF/GE blend nanofibrous membranes and the SF/GE-PCLshell-core structured composite nanofibrous membranes were assessed by the MTT method. Theexperimental results suggested that human skin fibroblasts (HSF) could adhere、grow andproliferate on the surface of the two kinds of scaffolds which possessed excellentbiocompatibility. The vivo experiments confirmed that the SF/GE scaffold had outstandingrepairing efficacy, and could promote angiogenesis, reduce the formation of scar.