Studies On The Eletrospinning Of Regenerated Silk Fibroin And Hydroproxypyl Chitosan Aqueous Solutions

As a natural material, Silk fibroin (SF)has little inflammation to human body, good biocompatibility and good permeability for water and oxygen. However the brittleness of SF limits its extensive application. Hydroproxypropyl chitosan (HPCS) is a derivatives of chitosan, which has not only broad-spectrum antimicrobial property but also better water-solubility. In this work, in order to utilize the advantages of these two materials and develop a new composite material, regenerated SF(RSF)/HPCS aqueous solutions were prepared and the electrospinning spinnability and optimum spinning parameters were investigated.The composite mats with different contents of HPCS were fabricated and then post-treated by ethanol. Both electrospun as-spun mats and post-treated mats were characterized by SEM, Raman spectroscopy, X-ray diffraction and other methods.It was found that the apparent viscosity and surface tension of RSF/HPCS blend aqueous solution slightly increased, while the conductivity of the solution raised obviously with the increase of HPCS content.The effects of the voltage, collect distance and flow rate of spinning dope on the morphology and properties of the mats were investigated. It was found that the optimum parameter are:a HPCS content of2%, a voltage of23kV, a collect distance of10cm and a flow rate of0.3mL/h. Under this condition, we fabricated a series of electrospun RSF/HPCS as-spun mats. The results showed that when the content of HPCS increased, the diameter of the as-spun composite fibers decreased, while the shape of the fiber was changed from cylinder-like to ribbon-like.Random coil/a-helix conformation and amorphous structure were still dominant in the as-spun mats.The post-treated mats showed higher content ofβ-sheet conformation and crystallinity compared with the as-spun mats. Especially, with the addition of appropriate amount(2%) of HPCS, the crystallinity of the mat reached up to51.7%.Compared with the neat RSF mats, the composite mats showed an enhancement of104%,126%and150%to breaking energy, breaking strength and initial modulus, respectively.In addition, MTT assay showed that the biocompatibility and proliferation activity of the composite post-treated mats were also improved.The in vitro degradation test showed that the degradation rate decreased with the increasing content of HPCS. The post-treated mats with3%of HPCS showed better anti-bacterial properties against E.coli than pure SF post-treated mats. However, both mats didn’t have obvious anti-bacterial properties against S.aureus.