Magnetite nanoparticles were synthesized by co-precipitation of Fe2+ and Fe3+ with NH3.H20, and then 3- aminopropyltriethoxysilane (APTES) was coated on the magnetite nanoparticles by silanization reaction to achieve Fe3O4/APTES nanostructures. After modified by APTES, the nanostructures were activated by glutaraldehyde (GA) to obtain functional groups on the nanostructures surface. Human Serum Albumin (HSA) was immobilised on the Fe3O4/APTES and Fe3O4/APTES/GA nanostructures. The morphology and properties of the nanoparticles were characterized by transmission electron microscopy (TEM), Xray diffraction (XRD), vibrating sample magnetometer (VSM), Fourier transform infrared spectroscopy (FTIR), UV–vis spectroscopy and thermal gravimetric analysis (TGA). The HSA binding efficiency was estimated by the Bradford method.