Glutathione-Activatable and O2/Mn2+-Evolving Nanocomposite for Highly Efficient and Selective Photodynamic and Gene-Silencing Dual Therapy

Photodynamic therapy (PDT) has been applied in cancer treatment by converting O-2 into reactive singlet oxygen (O-1(2)) to kill cancer cells. However, the effectiveness of PDT is limited by the fact that tumor hypoxia causes an inadequate O-2 supply, and the overexpressed glutathione (GSH) in cancer cells consumes reactive oxygen species. Herein, a multifunctional hybrid system is developed for selective and highly efficient PDT as well as gene-silencing therapy using a novel GSH-activatable and O-2/Mn2+-evolving nanocomposite (GAOME NC). This system consists of honeycomb MnO2 (hMnO(2)) nanocarrier loaded with catalase, Ce6, and DNAzyme with folate label, which can specifically deliver payloads into cancer cells. Once endocytosed, hMnO(2) carriers are reduced by the overexpressed GSH to Mn2+ ions, resulting in the reduction of GSH level and disintegration of GAOME NC. The released catalases then trigger the breakdown of endogenous H2O2 to generate O-2, which is converted by the excited Ce6 into O-1(2). The self-sufficiency of O-2 and consumption of GSH effectively enhance the PDT efficacy. Moreover, DNAzyme is freed for gene silencing in the presence of self-generated Mn2+ ions as cofactors. The rational synergy of enhanced PDT and gene-silencing therapy remarkably improve the in vitro and in vivo therapeutic efficacy of cancers.