Three near-infrared and lysosome-targeting probes for photodynamic therapy (PDT)

Lysosome, an organelle which contains a number of hydrolases and hydrogen ions, plays a crucial role in cellular survival and apoptosis. If selectively destroy lysosomes membrane, inner hydrolases and hydrogen ions will leak and induce cell death. In this work, three lysosome-targeting fluorescent probes (HCL 1-3, heptamethine cyanine lysosomal-targeting probe) were designed, synthesized and developed for photodynamic therapy. Piperazine and N, N-dimethyl structures made HCL 1-3 have good lysosome targeting ability while Pearson's correlation coefficients reached 0.85, 0.87 and 0.78. It can be concluded from MTT test, HCL 1-3 have high photo cytotoxicity and low dark cytotoxicity from MTT test. Calcein/PI staining assays also supported cytotoxicity of HCL 1-3 under light conditions. In vivo experiments, HCL 2 accumulated in tumor and a strong fluorescence signal was observed at 12 h post injection. All results showed that our experiments provide help and new ideas for cyanine dyes in cancer treatment.