Facile organic solvent-free synthesis of size-controlled hierarchically structured magnetic hollow spheres and potential application in adsorption for bovine serum album.

A series of size-controllable hierarchically nanostructured magnetic hollow spheres (MHS) (250-2330 nm) have been fabricated by using the hard-template method involving the coprecipitation of ferrite precursor over the pre-synthesized polystyrene spheres with varied sizes under organic solvent-free conditions followed calcinations. The SEM, TEM and HRTEM results indicate that the primary nanoparticles constructing hierarchically nanostructured MHS clearly show the template sphere size-dependent changes in morphologies and stacking modes from disorderly stacked globular and nanorodlike mixed particles, to orderly perpendicularly oriented nanorodlike particles, and to compact horizontally arranged nanospindle particles as the template size is increased. The N(2) adsorption-desorption data reveal that the MHS spheres have a high BET surface area (48-83 m(2)/g) and large pore volumes (0.37-0.66 cc/g). The vibration sample magnetization analysis shows that the MHS spheres have moderate magnetization saturation of 24-37 emu/g. The adsorption results show that the BSA adsorbance is greatly affected by the varied morphologies and stacking modes of primary nanoparticles constructing the MHS spheres and the maximum adsorption occurs on the MHS spheres mainly comprised of perpendicularly oriented nanorodlike primary particles.