Anthracene-based fluorescent MOFs decorated by platinum nanozymes as a multifunctional nanoplatform for enhanced photodynamic therapy and self-monitoring of real-time singlet oxygen

Singlet oxygen (1O2) is one of the primary reactive oxygen species (ROS) during photodynamic therapy (PDT), so monitoring the generation of 1O2 is of tremendous help for evaluating the PDT efficacy and further adjusting the treatment regimens. However, of particular note, the PDT efficacy is restricted by the intrinsic hypoxic problem of tumor microenvironment. Herein, anthracene-based fluorescent MOFs decorated by platinum (Pt) nanozymes (TCPP@DPA-MOF-Pt, TDMP) as a multifunctional therapeutic and sensing nanoplatform was fabricated to achieve the integration of PDT effect, O2 self-sufficiency, and intracellular 1O2 self-monitoring. The Pt-decorated fluorescent nanoplatform displayed sustained H2O2 catalytic ability and superior 1O2 sensing performance in solution. At the cellular level, it exhibited satisfactory biocompatibility and enabled be efficiently internalized into the cells on account of an appropriate particle size (~100 nm). More importantly, in the hypoxic environment, the surface-decorated Pt NPs served as catalase-mimicking nanozymes and were able to effectively achieve O2 self-sufficiency, thereby greatly improving the efficacy of PDT. Simultaneously, the anthracene ligand DPA could real-time monitor intracellular 1O2 during PDT through self-fluorescence quenching, thus realizing a self-feedback function for PDT efficacy tracking. This study offers an innovative strategy to integrate fluorescent MOFs and nanozymes into a nanoplatform for achieving enhanced PDT efficacy and intracellular 1O2 selfmonitoring during PDT.