Modification Of Silk Fibroin And Its Application In Drug Release

In general, nature Bombyx mori cocoon is composed of silk fibroin proteins which account for70%to80%in the total silkworm cocoon by weight coated with sericin proteins. Silk fibroin (SF), a unique material which derived from Bombyx mori cocoons, has been widely used in the textile industry for thousands of years for the outstanding aesthetic and sensorial properties. Nowadays, silk fibroin have gained more and more attentions for biomaterial applications for the desirable properties, such as non-toxic, non-irritating and the excellent biocompatibility and readily that allows human and mammal cells to adhere and proliferate.To elucidate the physicochemical properties of silk protein, several solvent systems were adopted to dissolve silk fibroin and the differences in the behavior of these solvents were investigated. Here we compare the effects of these systems on the stability and the flow time via Ubbelohde viscometer of silk fibroin solution and on protein secondary structure as revealed by FTIR spectroscopy of cast membranes. The results demonstrated that LiBr-H2O had moderate solvation on the silk fibroin molecules and peptide chains which could be used to study the conformation changes in silk fibroin.However, silk fibroin films can not be used directly for the essential drawbacks such as frangibility, inflexibility, low mechanical strength and high solubility in water. Polyethylene glycol diglycidyl ether (PEGO) which synthesized by poly (ethylene glycol) and chloroepoxy propane was added to improve the inherently disadvantages of the silk fibroin. The changes on the secondary structure, crystallization, thermal properties, the surface morphology and mechanical properties of the blend films were systematically discussed by Fourier infrared spectroscopic (FTIR), X-Ray diffraction (XRD), differential scanning calorimeter (DSC), scanning electron microscopy (SEM) and universal testing machine. In addition, moisture content, swelling index, water absorption and weight loss have also been measured. The results indicated that with the introduction of PEGO, the interactions between SF and PEGO in the blend films induce the conformation transition of SF from silk I to silk II structure, while the PEGO content reached to50%, the SF expressed opposite changes. The SEM analysis showed that the blend films have good intermiscibility in SP50, SP70and SP90; the elongation at break of blend membranes reach80.225%in SP50; moisture content, swelling index, total water absorption and film weight loss showed the minimum value in SP50.The silk films modificated with PEGO were used as the carrier for drug release and the release behavior was investigated. The results indicated that the process of drug release appears first quick back slow trend and the induced of PEGO slows down the drug release rate.