The concept and examples of type-III photosensitizers for cancer photodynamic therapy

In conventional photodynamic therapy (PDT), reactive oxygen species are produced to kill cancer cells based on type-I and type-II mechanisms, and the sensitization of photosensitizers is oxygen dependent. However, solid tumors reside in a hypoxic milieu, which hampers the therapeutic efficacy of photosensitive drugs against tumors. Novel photosensitizers NBEX (X = S, Se, Te) were designed to bind to RNA without interference by other species and to transfer excitation-state energy directly to destroy RNA in cancer cells. This process of killing cancer cells is completely independent of oxygen (type-III mechanism). Remarkably, NBEX (X = S, Se, Te) could self-assemble into nanoparticles and accumulate in the tumor area within tens of minutes in vivo. NBESe exhibited an excellent performance for killing solid tumors and inhibited tumormetastasis. Simultaneously, PDT could induce the immune response to tumors. This novel photosensitizer could be a candidate for cancer treatment in clinical practice.

Automated summary

Conventional photodynamic therapy is hindered by the hypoxic environment of solid tumors, but novel photosensitizer NBEX (X = S, Se, Te) can destroy RNA in cancer cells without oxygen and accumulate in tumor area quickly.