Zinc oxide end-capped Fe3O4@mSiO2 core-shell nanocarriers as targeted and responsive drug delivery system for chemo-/ions synergistic therapeutics.

Multifunctional core-shell nanocarriers based on zinc oxide (ZnO)-gated magnetic mesoporous silica nanoparticles (MMSN) were prepared for cancer treatment through magnetic targeting and pH-triggered controlled drug release. Under an external magnetic field, the MMSN could actively deliver chemotherapeutic agent, daunomycin (DNM), to the targeted sites. At neutral aqueous, the functionalized MMSN could stably accommodate the DNM molecules since the mesopores were capped by the ZnO gatekeepers. In contrast, at the acid intercellular environment, the gatekeepers would be removed to control the release of drugs due to the dissolution of ZnO. Meanwhile, ZnO quantum dots not only rapidly dissolve in an acidic condition of cancer cells but also enhance the anti-cancer effect of Zn2+. An in vitro controlled release proliferation indicated that the acid sensitive ZnO gatekeepers showed well response by the 'on-off' switch of the pores. Cellular experiments against cervical cancer cell (HeLa cells) further showed that functionalized MMSN significantly suppressed cancer cells growth through synergistic effects between the chemotherapy and Zn2+ ions with monitoring the treatment process. These results suggested that the ZnO-gated MMSN platform is a promising approach to serve as a pH-sensitive system for chemotherapies delivery and Zn2+ controlled release for further application in the treatment of various cancers by synergistic effects.