Hollow/rattle-type mesoporous nanostructures by a structural difference-based selective etching strategy

A novel "structural difference-based selective etching" strategy has been developed to fabricate hollow/rattle-type mesoporous nanostructures, which was achieved by making use of the structural differences, rather than traditional compositional differences, between the core and the shell of a silica core/mesoporous silica shell structure to create hollow interiors. Highly dispersed hollow mesoporous silica spheres with controllable particle/pore sizes could be synthesized by this method, which show high loading capacity (1222 mg/g) for anticancer drug (doxorubicin). Hemolyticity and cytotoxicity assays of hollow mesoporous silica spheres were conducted, and the synthesized hollow mesoporous silica spheres with large pores show ultrafast immobilization of protein-based biomolecules (hemoglobin). On the basis of this strategy, different kinds of heterogeneous rattletype nanostructures with inorganic nanocrystals, such as Au, Fe₂O₃, and Fe₃O ₄ nanoparticles, as the core and mesoporous silica as the shell were also prepared. This strategy could be extended as a general approach to synthesize various hollow/rattle-type nanostructures by creating adequate structural differences between cores and shells in core/shell structures in nanoscale.