Adsorption of biomolecules on mesostructured cellular foam silica: Effect of acid concentration and aging time in synthesis

Mesostructured cellular foam (MCF) silica was synthesized using a non-ionic surfactant template-directed method without ammonium fluoride: the acid concentration and aging time were varied to determine the effects of these parameters on the final material. Increasing the acid concentration and aging time resulted in larger window size, which is critical in gating of biomolecule access to the interior of the MCF silica. In particular, when the acid concentration was changed from 1.6 to 3.5 M the window pore dimension approximately doubled, although the pore size distribution was broader. In this study, the optimal synthesis conditions to produce large, narrowly distributed window pores are 3.5 M HCl with an aging time of 20 h. The loadings of L-tryptophan (Trp), lysozyme (LYS) and bovine serum albumin (BSA) on the MCF samples were measured using batch adsorption. Adsorption data followed a Type I isotherm. The monolayer adsorption capacity of Trp on acid-washed MCF was several times higher than that of LYS and BSA, because of the smaller size of Trp. Protein adsorption onto MCF silica showed minimal size exclusion until the window size of the silica was barely larger than the largest protein dimension. (C) 2011 Elsevier Inc. All rights reserved.