Investigation on the precipitation, microenvironment and recovery of protein in CO 2-expanded reverse micellar solution

Abstract

The effect of compressed CO 2 on the properties of protein (trypsin) in the reverse micelles of sodium bis(2-ethylhexyl)sulfosuccinate AOT/decane/water has been studied. UV-vis spectrum was used to determine the precipitation of trypsin in the reverse micelles, which reveals that trypsin can be precipitated from the reverse micelles by compressed CO 2 at suitable pressures, while the surfactant AOT remains in the solution. FT-IR spectroscopy was used to investigate the microenvironment of trypsin in the CO 2-expanded reverse micelles, which shows that the micropolarity inside the micelle cores is changed gradually with the CO 2 pressure. Using compressed CO 2 as antisolvent, the protein in the reverse micelles can be recovered, and trypsin nanoparticles with the size of less than 15 nm were obtained, which was characterized by transmission electron microscopy (TEM).