Preparation of magnetic iron/mesoporous silica composite spheres and their use in protein immobilization

The iron/silica magnetic composite spheres were prepared by electrochemical method and reduced in hydrogen atmosphere at different temperatures. The morphology and structure of the composite were characterized by SEM, TEM and XRD. The iron/silica microspheres exhibit essential ferromagnetic behavior characterized by magnetometry. After being coated with silica in sodium silicate solution by acidifying technology, the surface of these magnetic composite spheres is with amino-silane coupling agent for their attachment to affinity ligands. 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 was studied. The results show that such amino-silane modified magnetic composite spheres are the effective supports for bioseparation and the maximum BSA immobilization capacity (up to 87.4 mg/g) is obtained in 0.1 mol/L phosphate buffer at pH 5.0.