The combination of in situ photodynamic promotion and ion-interference to improve the efficacy of cancer therapy

Photodynamic therapy (PDT) is proved to be a promising modality for clinical cancer treatment. However, it also suffers from a key obstacle in association with its oxygen-dependent nature which greatly limits its effective application against hypoxic tumors. Herein, on the basis of the unique property of calcium peroxide (CaO2), we propose an O2-self-supply strategy for the promotion of PDT by combining the in situ O2-generation characteristic of calcium peroxide with the photosensitive nature of porphyrin. A shell of ZIF-8 was synthesized surround the CaO2 core to prevent the CaO2 from premature decomposition and increased the loading of THPP efficiently. Depending on the in situ self-supply of O2, the photosensitizer was able to exhibit an enhanced PDT effect that significantly inhibit the growth of tumor. Moreover, the enrichment of free calcium ions derived from the decomposition of CaO2 under acidic tumor microenvironment also shows the unique ion-interference effect and contributes to the obvious inhibition against tumor growth. This work presents a synergistic strategy for the construction of a photodynamic promotion/ion-interference combined nano-platform which can also serve as an inspiration for the future design of effective nanocomposites in tumor treatment.