Type I photosensitizer based on AIE chromophore tricyano-methylene-pyridine for photodynamic therapy

Image guided photodynamic therapy(PDT) combines fluorescence tracing and phototherapy, which can achieve a more accurate and effective treatment effect. However, traditional photosensitizers are limited by the aggregation-caused fluorescence quenching(ACQ) effect and low reactive oxygen species(ROS) generation in a hypoxic environment, resulting in poor imaging and treatment effect. Herein, we report a tricyano-methylenepyridine(TCM)-based Type I aggregation-induced emission(AIE) photosensitizer(TCM-MBP), the strong electron acceptance(D-A) effect extends the wavelength to near-infrared(NIR) region to reduce the autofluorescence interference, and oxygen atoms provide lone pair electrons to enhance the inter system crossing(ISC) rate,thereby promoting the generation of more triplet states to produce ROS. The AIE photosensitizer TCM-MBP exhibited low oxygen dependence, NIR emission, and higher ROS production compared to commercially available Ce 6 and RB. After encapsulation with DSPE-PEG2000, TCM-MBP nanoparticles(TCM-MBP NPs) could penetrate to visualize cells and efficiently kill cancer cells upon light irradiation. This study provides an oxygenindependent AIE photosensitizer, which has great potential to replace the commercial ACQ photosensitizers.