Engineering the mesopores of Fe3O4@mesosilica core-shell nanospheres through a solvothermal post-treatment method

A solvothermal post-treatment method was developed to synthesize Fe(3)O(4)@mesosilica core-shell nanospheres (CSNs) with a well-preserved morphology, mesoporous structure, and tunable large pore diameters (2.5-17.6 nm) for the first time. N,N-Dimethylhexadecylamine (DMHA), which was generated in situ during the heat-treatment process, was mainly responsible for this pore-size enlargement, as characterized by NMR spectroscopy. This pore-size expansion can be strengthened with the aid of hexamethyldisilazane (HMDS), whilst the nature of the surface of the Fe(3)O(4)@mesosilica CSNs can be easily modified with trimethylsilyl groups during the pore-size-expansion process. The hydrophobicity of the Fe(3)O(4)@mesosilica CSNs increased for the enlarged mesopores and the adsorption capacity of these CSNs for benzene (up to 1.5 g g(-1)) is the highest ever reported for Fe(3)O(4)@mesosilica CSNs. The resultant Fe(3)O(4)@mesosilica CSNs (pore size: 10 nm) showed a 3.6-times higher adsorption capacity of lysozyme than those without the pore expansion (pore size: 2.5 nm), thus making them a good candidate for loading large molecules.