Designing NIR AIEgens for lysosomes targeting and efficient photodynamic therapy of tumors.

Cancer is the most severe health problem facing most people today. Photodynamic therapy (PDT) for tumors has attracted attention because of its non-invasive nature, negligible adverse reactions, and high spatiotemporal selectivity. Developing biocompatible photosensitizers that can target, guide, and efficiently kill cancer cells is desirable in PDT. Here, two amphiphilic organic compounds, PS-I and PSS-II, were synthesized based on the D-π-A structure with a positive charge. The two AIEgens exhibited near-infrared emission, large Stokes shift, high O and O generation efficiency, good biocompatibility, and photostability. They were co-incubated with cancer cells and eventually accumulated to lysosomes by cell imaging experiments. In vitro and in vivo experiments demonstrated that PS-I and PSS-II could effectively kill cancer cells and sufficiently inhibit tumor growth under light irradiation. PS-I had a higher fluorescence quantum yield in the aggregated state, which made it better for bio-imaging in imaging-guided photodynamic therapy. In contrast, PSS-II with a longer conjugated structure had more ROS generation to kill tumor cells under illumination, and the tumor growth inhibition of mice reached 71.95% during the treatment. No observable injury or undesirable outcomes were detected in the vital organs of the mice within the treatment group, suggesting that PSS-II/PS-I had a promising future in efficient imaging-guided PDT for cancer.