Silk Fibroin Degradation Related to Rheological and Mechanical Properties.
作者信息
Partlow Benjamin P, Tabatabai A Pasha, Leisk Gary G, Cebe Peggy, Blair Daniel L, Kaplan David L
机构信息
Department of Biomedical Engineering, Tufts University, 4 Colby St., Medford, MA, 02155, USA.
Department of Physics Institute for Soft Matter Synthesis and Metrology, Georgetown University, 506 Reiss Science Building 37th and O Streets, N. W., Washington, D.C., 20057, USA.
出版信息
Macromol Biosci. 2016 May;16(5):666-75. doi: 10.1002/mabi.201500370. Epub 2016 Jan 12.
Regenerated silk fibroin has been proposed as a material substrate for biomedical, optical, and electronic applications. Preparation of the silk fibroin solution requires extraction (degumming) to remove contaminants, but results in the degradation of the fibroin protein. Here, a mechanism of fibroin degradation is proposed and the molecular weight and polydispersity is characterized as a function of extraction time. Rheological analysis reveals significant changes in the viscosity of samples while mechanical characterization of cast and drawn films shows increased moduli, extensibility, and strength upon drawing. Fifteen minutes extraction time results in degraded fibroin that generates the strongest films. Structural analysis by wide angle X-ray scattering (WAXS) and Fourier transform infrared spectroscopy (FTIR) indicates molecular alignment in the drawn films and shows that the drawing process converts amorphous films into the crystalline, β-sheet, secondary structure. Most interesting, by using selected extraction times, films with near-native crystallinity, alignment, and molecular weight can be achieved; yet maximal mechanical properties for the films from regenerated silk fibroin solutions are found with solutions subjected to some degree of degradation. These results suggest that the regenerated solutions and the film casting and drawing processes introduce more complexity than native spinning processes.