Preparation Of Silk Fibroin Peptide/ Polyethylene Glycol Compound And Study Of Its Biocompatibility

Silk Fibroin (SF) as a natural protein fiber has been used long before. Recently, many studies with SF showed which is good at biocompatibility, slow degradation rate, low immunogenicity, and is a kind of good bio-materials. Whereas there were many disfigurements with SF then the modification of SF has been studied. In this paper, Polyethylene glycol (PEG) was used to modify the SF to obtain a new compound which was should be used as a kind of biomaterials and studied its biological performance.SF was prepared from cocoon, and then Nano-scale particles of silk fibroin (SFP) could be received through the enzymolysis of Proteinase Neutral. Synchronously the acylation of PEG was grafted to the molecule of Nano-SFP, which prepare the compound of Nano-SFP/PEG. From this characteristic then the best prorate between SFP and acylation of PEG was be known, which was 1:10 and the percentage of reaction was 93.8%.The results of amino acid analysis with Nano-SFP showed that the active districts of SF didn't be destroyed Proteinase Neutral. Compound was characterized by infrared spectroscopy (IR) measurement and showed the acylation of PEG was grafted to SFP successfully. After the modification with PEG, the SFP could not be dissolved in the neutral salt solutions of CaCl₂, which showed the SFP was steadier than before. Besides, the compound of SFP/PEG could not be dissolved in the artificial gastric juice, which was fit for the accidence of pharmaceutical adjuvant. Cytotoxicity with the compound being tested by L-929 cells in vitro,the cytotoxicity of all the samples was graded"0"or"1"by the criteria. There was no cytotoxicity with the compound, but also promoted the growth of L-929 cells at the certain extent. These all showed the compound in this paper should have good compatibility with L929 cells. The silk fibroin peptide and the SFP/PEG compound all have antibacterial effects to Staphylococcus aureus and E.coli. Thereby the SFP/PEG compound should have the potentiality as the biomaterial or pharmic material.