Periodic mesoporous organosilica coupled with chlorin e6 and catalase for enhanced photodynamic therapy to treat triple-negative breast cancer.

Photodynamic therapy (PDT) has become a promising treatment option for highly aggressive triple-negative breast cancer (TNBC); however, hypoxia limits the efficacy of PDT and promotes tumour aggression. In this work, we first constructed a multifunctional yolk-shell structured nanoplatform consisting of periodic mesoporous organosilica (PMO) coupled with chlorin e6 (Ce6) and catalase (Catalase) (Yolk-Shell PMO-Ce6@Catalase) for enhanced PDT against TNBC. This nanoplatform has an organic-inorganic hybrid skeleton structure, a uniform size and good stability and biocompatibility. In vitro experiments showed that the nanoplatform has a good ability to generate singlet oxygen. Catalase can convert H2O2 into O2, increasing the concentration of oxygen around the cells and overcoming the problem of hypoxia in the tumour, which enhances the effects of PDT. The in vivo experimental results showed that PDT with the Yolk-Shell PMO-Ce6@Catalase nanoplatform, compared with free Ce6 and Yolk-Shell PMO-Ce6 PDT, can significantly inhibit tumour growth, revealing the most extensive cellular apoptosis and necrosis in the tumour area in this treatment group. Additionally, the histopathological results showed that PDT did not cause significant side effects to the major organs. Therefore, we believe that this Yolk-Shell PMO-Ce6@Catalase nanoplatform has excellent clinical potential for PDT against TNBC.