Fabrication of Mesoporous SiO2@CaSiO3 Hollow Spheres as Carriers for pH-sensitive Drug Delivery

Hollow mesoporous silica(HM-SiO 2 ) was prepared by the improved stober method. On this basis, HM-SiO 2 was dispersed in an alkaline solution for surface etching. Meanwhile, calcium source was introduced to combine with SiO 2− 3 on the surface to form a CaSiO 3 shell layer and an unprecedent SiO 2 @CaSiO 3 sphere with a hollow double-shell structure was obtained. The as-synthesized SiO 2 @CaSiO 3 was characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM), transmission electron microscopy(TEM), N 2 -BET, IR and UV-Vis techniques, and its sustained release capacity of doxorubicin(DOX) loading was investigated. The drug loading capacity can be achieved to 0.692 mg DOX/mg SiO 2 @CaSiO 3 , exhibiting pH-responsivity under low pH conditions.