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

Hollow mesoporous silica(HM-SiO₂) was prepared by the improved stober method. On this basis, HM-SiO₂ was dispersed in an alkaline solution for surface etching. Meanwhile, calcium source was introduced to combine with on the surface to form a CaSiO₃shell layer and an unprecedent SiO₂@CaSiO₃sphere with a hollow double-shell structure was obtained. The as-synthesized SiO₂@CaSiO₃ was characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM), transmission electron microscopy(TEM), N₂-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 SiO₂@CaSiO₃, exhibiting pH-responsivity under low pH conditions.