Preparative protein purification on underivatized silica.

This article describes the use of underivatized silica gel as a preparative stationary phase for process purification of proteins. Although silica has been frequently used as a stationary phase backbone matrix, direct adsorption of proteins on underivatized silica has not been widely exploited for industrial applications. In this study an effort was made to fundamentally understand the interaction mechanisms between a protein and silica surface by using several proteins with a wide range of isoelectric points (pIs) and surface hydrophobicity. Interactions in silica were found to be largely dominated by a combination of ionic and hydrophobic forces. Accordingly, a predictive model was derived for describing linear retention of proteins on silica. Finally, a case study is described investigating the role of silica in an industrial purification process. It was found that the integration of the two modes of interaction confers silica with a unique selectivity that can be very effectively utilized in downstream bioprocessing.