Two strategies of enhancing the therapeutic potential of a coumarin probe: Integration of a protonatable moiety and BSA-based nanoparticle formation

Photodynamic therapy (PDT) represents a promising non-invasive approach for cancer treatment, relying on photosensitizers (PSs) to generate reactive oxygen species (ROS) upon light activation. This study aims to enhance the therapeutic potential of a coumarin-based fluorescent probe by employing two strategic modifications: the integration of a protonatable lysosome-targeting moiety and the formation of bovine serum albumin (BSA)-based nanoparticles. The COM molecule was synthesized with a morpholine moiety to facilitate lysosome targeting and protonation in acidic environments, thereby enhancing ROS production and promoting lysosomal dysfunction for increased cancer cell apoptosis. Additionally, COM was encapsulated in BSA nanoparticles (COM-BSA NPs) to leverage hydrophobic interactions and hydrogen bonding, which enhance ROS generation by promoting the intersystem crossing (ISC) process. Comprehensive photophysical studies confirmed the enhanced ROS generation under acidic conditions and within BSA-based NPs. Cellular experiments demonstrated effective lysosome targeting and anticancer efficacy of both COM and COM-BSA NPs. These findings highlight the dual benefits of maintaining the bioimaging capabilities of coumarin while significantly improving its therapeutic efficacy in PDT applications.