Influence of shear on the structures and properties of regenerated silk fibroin aqueous solutions

Abstract

In this paper, the structures and properties of regenerated silk fibroin (RSF) aqueous solutions under shear were investigated by using a polarizing microscope, an optical shearing instrument, a rotational rheometer, a Raman spectrometer and a synchrotron radiation small angle X-ray scattering facility. It was found that after being sheared at a constant shear rate for a suitable time, the RSF aqueous solution showed gradually decreased viscosity and enhanced birefringence before protein denaturation. Meantime, rod-like structures were formed and conformational transition happened in the solution. These results indicated that the RSF molecules in the solution might gradually form rod-like liquid crystal structures after applying sufficient shear. Moreover, it was also found that the increase of the shear rate could reduce the critical shear time for the solution to begin to form the liquid crystal structure.