Enzyme-loaded manganese−porphyrin metal−organic nanoframeworks for oxygen-evolving photodynamic therapy of hypoxic cells

Photodynamic therapy (PDT) is attracting great attention for cancer treatments, while its therapeutic efficacy is limited by unsatisfactory photosensitizers and hypoxic tumor microenvironment (TME). To address these problems, we have developed catalase-loaded manganese-porphyrin frameworks (CAT@MnPFs) for catalytically-assisted PDT of cancer cells. CAT@MnPFs were constructed by the assembly of Mn2+ ions and PpIX into MnPFs and the subsequent loading of catalase. Under 650 nm light irradiation, the porphyrin (Protoporphyrin IX) within the structure of CAT@MnPFs can convert oxygen (O2) into singlet oxygen (1O2), showing the photodynamic effect. Importantly, the loaded catalase can decompose hydrogen peroxide (H2O2) into O2 with a huge elevation of O2 level (13.22 mg L−1) in 600 s, thus promoting 1O2 generation via PDT. As a result, CAT@MnPFs combined with 650 nm light can effectively ablate cancer cells due to the catalase-assisted oxygen-evolving PDT, showing a high therapeutic efficacy. Meanwhile, after the incubation with CAT@MnPFs, unobvious damage can be found in normal and red blood cells. Thus, the obtained CAT@MnPFs integrate the advantage of photosensitizers and catalase for oxygen-evolving PDT, which can provide some insight for treating hypoxic cells.