Molecular-engineered highly photosensitive triarylphosphine oxide compounds for apoptosis imaging and selectively inducing apoptosis of tumor cells by photodynamic therapy

Although photodynamic therapy (PDT) has wide applications, tumor-targeting probes with high photosensitivity or apoptosis-monitoring capability, which possess low phototoxicity and can be used for evaluating therapeutic efficacy, are still scarce. In this study, we constructed a series of highly photosensitive probes by introducing multivalent positive charges around propeller-like triarylphosphine oxide compounds. Some of them can be used to detect apoptosis by selectively entering apoptotic cells in the presence of living or necrotic cells. Among them, OTPP-6-Amyl can target SKOV-3 cells by binding to their membrane in a short time and move to mitochondria with prolonging time and can be further applied for imaging SKOV-3 tumors in vivo, whereas for various apoptotic cells, it mainly enters the nucleus. Its high photosensitivity can be used to induce apoptosis in SKOV-3 cells without affecting the survival of other cells. By functionalizing with cRGD, another probe was constructed to target U87MG cells and induce their apoptosis by PDT, and it can also pass through the blood-brain barrier.