Self-assembly Behavior Of Tussah Silk Fibroin And Application In Drug Controlled Release

Tussah silk fibroin (TSF) is the natural protein, which can be used as biomaterials, e.g. surgical suture, scaffold for tissue engineering, wound covering material, soft contact lens and controlled release carrier, because it has good biocompatibility and biodegradability. Tussah silk fibroin can be decomposed by specific enzyme to non-toxic products for body and not easy to cause inflammation and immune rejection. In view of these characteristics, the microspheres and tissue engineering loaded drug had good application in medicine.Molecular self-assembly was the process that intermolecular formed molecular aggregates or supermolecular structure through non-covalent interactions spontaneously in the equilibrium conditions. Controlled release drug system refered that the controlled release was in zero order or nearly constant speed release under the controlled action in order to get a more stable concentration of blood medicine in the body.In this paper, we adapted a new method to prepare protein-based nanospheres and porous scaffolds based on regenerated tussah silk fibroin self-assembling in specific conditions. we studied the application of clinical medicine previous and used low-toxic and non-toxic solvent to induct tussah silk fibroin to preparate microsphere and porous scaffolds.First, we adopted the microscope, FEGTEM, dynamic scattering, laser particle size analyzer, FTIR to test appearance, size and internal components of microspheres. The results showed that the size of the microspheres decreased, but the crystallinity improved with the increase of ethanol. FEGTEM showed that the ball had the surface of the bumpy. When we added ethanol 9ml, average particle size was 184.52 nm and scattered index 0.2903.Second, TSF porous scaffolds were prepared by a technique integrating mixed solution casting and protein conformational transition under specific conditions. We used SEM to observe the porous scaffolds section pattern and the size of the aperture. With the increase of concentration of tussah silk solution, we found that the crystallinity improved and porous gradually becomed small and even. The prepared porous scaffolds were highly porous with 80% porosity and a controllable pore size of 10～225μm. Scaffolds with different geometrical shapes can be prepared depending on the geometries of moulds only. When the concentration of tussah silk solution was larger, the degree of conformation transition was more and the density becomed larger, and the composition of the silkⅡand strength also increased. With the increase of concentration, X-ray diffraction showed the silkⅡof porous scaffolds mainly distributed 17.2°,19.72°and 29.42°.Third, we researched controlled drug delivery with silk fibroin microsphere and porous scaffolds loaded drug and the result showed that the time of drug released was significantly longer. The process of drug release divided into two stages:rapid release in the early stage and slow release in the late stage. The drug loaded can reduce side effects and improve the the efficiency of the drug. TSF porous scaffolds loaded drug rate were slightly higher than the microspheres.Microspheres and porous scaffolds based on the TSF self-assemble has a very good application prospect in drug release.