Bioactive SiO2-CaO-P2O5 hollow nanospheres for drug delivery

• Monodispersed hollow SiO2-CaO-P2O5 nanospheres were prepared.
• The nanospheres exhibited high biocompability and low cytotoxicity.
• High drug-loading capacity and sustained multistep release of theophylline in the hollow nanospheres were achieved.

Hollow nanospherical bioactive glasses have attracted much interest in the recent years because of their important applications in drug delivery and hard tissue repair. Herein, we developed a facile method to fabricate bioactive SiO2-CaO-P2O5 (SCP) hollow nanospheres using polystyrene (PS) nanospheres as the hard template. The removal of PS templates by heating produced almost monodispersed hollow SCP nanospheres with an inner cavity of 210 nm, making them suitable for drug delivery. The impact of the glass composition on the formation of hollow SCP nanospheres was investigated in detail. High drug-loading capacity and sustained multistep release of theophylline in the SCP nanospheres were achieved. Furthermore, the SCP nanospheres exhibited apatite-forming ability when immersed in a simulated body fluid. Cytotoxicity of SCP nanospheres on live cells has been evaluated. The SCP hollow nanospheres with sustained drug release property and bioactivity are promising new-generation biomaterials.