Magnetic Fe3O4@mesoporous silica (MS) composites were synthesized by generating Fe3O4 nanoparticles in the mesoporous silica matrix using the sol-gel method in nitrogen atmosphere. The mesoporous silica hosts include SBA-15 particles owning highly ordered p6mm mesostructure, siliceous mesostructured cellular foams (MCFs), and fiber-like mesoporous silica (FMS) with unique pore structures. The X-ray diffraction (XRD), transmission electron microscopy (TEM), and N-2 adsorption/desorption results show that Fe3O4 functionalized MCFs and FMS possess suitable mesoporous structure for the adsorption of both small-molecular drug and large biomolecules. The biocompatibility tests on L929 fibroblast cells using MTT assay reveal low cytotoxicity of these systems. These Fe3O4@mesoporous silica composites show sustained release properties for aspirin in vitro. The release of the aspirin molecules from the pores of the Fe3O4@mesoporous silica composites is basically a diffusive process. Fe3O4@MCFs and Fe3O4@FMS owning larger pore size are good candidates for the adsorption of bovine serum albumin (BSA). These magnetic composites can be potential vectors for drug delivery and bioadsorption. (C) 2012 Elsevier Inc. All rights reserved.