Functional two-photon cationic targeted photosensitizers for deep-seated tumor imaging and therapy

Two-photon (TP) have been innovatively researched in bio-imaging and photodynamic therapy (PDT) due to the near-infread (NIR) absorption and excellent spatial accuracy, especially for the subcutaneous and deep-seated tumor. For TP excited photosensitizers (PS), the NIR absorption and enough triplet state energy can be simultaneously realized by semi-excited mode. Thus, we reported a boron dipyrromethene based cationic two-photon photosensitizer (TP-Car-BDP) to promote the tumor targeting and optical physical properties for better imaging and therapeutic effect, using two neutral molecules (PG-Car-BDP, C10-Car-BDP) as comparison. As expected, the cationic group could accelerate oil-water balance and cellular uptake, realize structure-inherent targeting in vivo, and induced early apoptosis in PDT. The imaging and therapeutic property of TP-Car-BDP excited by one/two-photon was also compared to illustrate efficacy of TP. Moreover, the high singlet oxygen quantum yield (0.39) and excellent phototoxicity (IC50 of 25.5 nM, MB was 2960 nM) revealed the potential therapeutic capacity.