Strength in Numbers: A Giant NIR-II AIEgen with One-for-All Phototheranostic Features for Exceptional Orthotopic Bladder Cancer Treatment

Abstract

One-for-all phototheranostics that allows the simultaneous implementations of multiple optical imaging and therapeutic modalities by utilizing a single component, is growing into a sparkling frontier in cancer treatment. Of particular interest is phototheranostic agent with emission in the second near-infrared (NIR-II) window. Nevertheless, the practical uses of those conventional NIR-II agents are severely impeded by their unsatisfactory features including insufficient stability, low synthetic yield, to be extended absorption/ emission wavelengths, and inefficient phototheranostic outcomes. Developing exceptional phototheranostic agents is thus highly desirable yet remains formidably challenging. Herein, we synthesized two novel N-heteroacenes-based NIR-II luminogens, namely 2TT-PPT and 4TT-PBPT, by respectively employing pyrene-fused phenaziothiadiazoles and pyrene-fused bisphenaziothiadiazoles as acceptor skeletons. There is strength in numbers by increasing the fusing rings in N-heteroacenes moieties and numbers of appended donors. Compared to less ring-fused 2TT-PPT, the giant molecule 4TT-PBPT shows improved photophysical characteristics, such as enhanced light absorbance, red-shifted wavelengths, higher brightness, favorable reactive oxygen species (ROS) generation, and elevated photothermal conversion efficiency, which render 4TT-PBPT nanoparticles excellent fluorescence-photoacoustic-photothermal trimodal imaging guided photodynamic-photothermal synergistic therapy for orthotopic bladder cancer.