End Group Nonplanarization Enhances Phototherapy Efficacy of A-D-A Fused-Ring Photosensitizer for Tumor Phototherapy

Enhancing the phototherapy efficacy of organic photosensitizers through molecular design is a fascinating but challenging task. Herein, we propose a simple design strategy to first realize the generation of superoxide anion radical (O2 center dot-) by A-D-A fused-ring photosensitizers. Through replacing one cyano group of traditional end group with an ester group, we designed a novel nonplanar end group (A unit) to synthesize a novel A-D-A photosensitizer F8CA. In a comparison with its counterpart F8CN with the traditional end group, F8CA displays more loose packing and larger spin-orbit coupling constants. The F8CA nanoparticles showed higher photodynamic activities with the generation capability of singlet oxygen (1O2), hydroxyl radical (center dot OH), and O2 center dot-, while F8CN nanoparticles could only generate 1O2 and center dot OH. In addition, F8CA nanoparticles still remain high photothermal conversion efficiency (61%). As a result, F8CA nanoparticles perform well in hypoxia-tolerant tumor phototherapy. This study brings an effective design thought for A-D-A photosensitizers.

Automated summary

Enhancing the phototherapy efficacy of organic photosensitizers through molecular design is a challenging task. This study proposes a simple design strategy to generate superoxide anion radical using A-D-A fused-ring photosensitizers. By replacing one cyano group with an ester group, a novel nonplanar end group (A unit) was synthesized to design the A-D-A photosensitizer F8CA. F8CA nanoparticles showed higher photodynamic activities with the generation of singlet oxygen, hydroxyl radical, and superoxide anion radical compared to F8CN nanoparticles. Additionally, F8CA nanoparticles displayed high photothermal conversion efficiency. This study provides an effective design approach for A-D-A photosensitizers.