Cationization to boost both type I and type II ROS generation for photodynamic therapy

The pursuing of photosensitizers (PSs) with efficient reactive oxygen species (ROS) especially type I ROS generation in aggregate is always in high demand for photodynamic therapy (PDT) and photoimmunotherapy but remains to be a big challenge. Herein, we report a cationization molecular engineering strategy to boost both singlet oxygen and radical generation for PDT. Cationization could convert the neutral donor-acceptor (D-A) typed molecules with the dicyanoisophorone-triphenylamine core (DTPAN, DTPAPy) to their A-D-A & PRIME; typed cationic counterparts (DTPANPF(6) and DTPAPyPF(6)). Our experiment and simulation results reveal that such cationization could enhance the aggregation-induced emission (AIE) feature, promote the intersystem crossing (ISC) processes, and increase the charge transfer and separation ability, all of which work collaboratively to promote the efficient generation of ROS especially hydroxyl and superoxide radicals in aggregates. Moreover, these cationic AIE PSs also possess specific cancer cell mitochondrial targeting capability, which could further promote the PDT efficacy both in vitro and in vivo. Therefore, we expect this delicate molecular design represents an attractive paradigm to guide the design of type I AIE PSs for the further development of PDT.

Automated summary

In this study, a cationization molecular engineering strategy was used to enhance the generation of reactive oxygen species (ROS) for efficient photodynamic therapy (PDT). The cationization process improved the aggregation-induced emission (AIE) feature, promoted intersystem crossing (ISC) processes, and increased charge transfer and separation ability, leading to the efficient production of ROS, particularly hydroxyl and superoxide radicals. Additionally, the cationic AIE photosensitizers also exhibited specific cancer cell mitochondrial targeting capability, which further improved the efficacy of PDT.