Conformation transition of silk protein membranes monitored by time-resolved FT-IR spectroscopy - Conformation transition behavior of regenerated silk fibroin membranes in alcohol solution at high concentrations

The time-resolved FT-IR spectroscopy was used to monitor conformation transition processes of regenerated silk fibroin membranes induced by alcohol solutions of high concentrations (alcohol content ≥90%). It was found that neat methanol could induce conformation transition of silk fibroin, while ethanol and pure isopropanol could not. However, conformation transition of silk fibroin also occurred when 7-8 percent of water was present in the ethanol or isopropanol solution. The conformation transition rate increased with the increase of water content in the alcohol solution in the range of alcohol concentration studied. The experimental results suggest that the swelling of the membrane is a pre-requisite for the conformation transition of silk fibroin.