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

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.