ZnO-functionalized upconverting nanotheranostic agent: multi-modality imaging-guided chemotherapy with on-demand drug release triggered by pH.

Limited therapeutic efficiency and severe side effects in patients are two major issues existing in current chemotherapy of cancers in clinic. To design a proper theranostic platform seems thus quite needed to target cancer cells accurately by bioimaging and simultaneously release drugs on demand without premature leakage. A novel ZnO-functionalized upconverting nanotheranostic platform has been fabricated for clear multi-modality bioimaging (upconversion luminescence (UCL), computed tomography (CT), and magnetic resonance imaging (MRI)) and specific pH-triggered on-demand drug release. In our theranostic platform multi-modality imaging provides much more detailed and exact information for cancer diagnosis than single-modality imaging. In addition, ZnO can play the role of a "gatekeeper" to efficiently block the drug in the mesopores of the as-prepared agents until it is dissolved in the acidic environment around tumors to realize sustained release of the drug. More importantly, the biodegradable ZnO, which is non-toxic against normal tissues, endows the as-prepared agents with high therapeutic effectiveness but very low side effects. These findings are of great interests and will inspire us much to develop novel effective imaging-guided on-demand chemotherapies in cancer treatment.