Synthesis of amino-silane modified superparamagnetic silica supports and their use for protein immobilization

A novel method to synthesize amino-silane modified magnetic silica supports was reported for affinity separation. The magnetite (Fe3O4) nanoparticles were prepared by the coprecipitation of ferrous and ferric salts with NH4OH, and then their surface was coated with silica in sodium silicate solution by acidifying technology to form well-dispersed magnetic silica nanospheres. These magnetic silica nanospheres are of about 50-80 nm in diameter and exhibit superparamagnetic characteristics. The surface of these nanospheres was with amino-silane coupling agent for their attachment to affinity ligands. In this work, bovine serum albumin (BSA) was covalently immobilized onto the amino-silane modified magnetic silica supports by the glutaraldehyde method. The influence of pH, ionic strength as well as the initial protein concentration on BSA immobilization has been studied. The result shows that such amino-silane modified magnetic silica is a well-dispersed and effective superparamagnetic support for bioseparation and the maximum BSA immobilization capacity (up to 86 mg/g) was obtained in 0.1 M phosphate buffer at pH 5.0. (C) 2004 Elsevier B.V. All rights reserved.