Synthesis and bio-adsorptive properties of large-pore periodic mesoporous organosilica rods

Highly ordered large-pore periodic mesoporous organosilica (PMO) with a rodlike morphology was successfully synthesized at low acid concentrations and in the presence of inorganic salt using triblock copolymer P123 as a template. The inorganic salt can not only promote the formation of highly ordered mesoporous structure but also control the morphology of PMO materials. The adsorption of bovine heart cytochrome c (cyt c) on PMO was studied at different ionic strengths and pHs by comparing with the adsorption on pure silica materials with similar morphology and pore structure. The results show that the adsorbed amount reaches the maximum around the isoelectric point of cyt c and the PMO materials do not have higher adsorbed capacity than SBA-15 silica. The specific adsorption amounts of cyt c on PMO or pure silica decrease as ionic strengths increase at all pH conditions. Our results directly support the conclusion that the electrostatic interaction between cyt c and PMO/pure silica surface is more dominant than hydrophobic forces in the bioadsorption of cyt c.