A NIR-II AIEgen with superior fluorescence and photothermal performance for precision theranostics

Second near-infrared (NIR-II; 1000 to 1700 nanometers) aggregation-induced emission luminogens (AIEgens) hold great promise for imaging-guided precision tumor phototherapy yet are limited by the intrinsic trade-off between fluorescence brightness and photothermal performance. Existing design strategies often yield complex molecular structures while inadequately addressing this trade-off. Herein, we propose a “Minor Tweaks, Major Leaps” concept: Simple modification of the star NIR-II AIEgen 2TT- o C6B (less than 5% change in molecular weight) markedly improves both NIR-II fluorescence brightness and photothermal performance. The thus-obtained new NIR-II AIEgen, ST-CZ , ranks among leading phototheranostic agents, exhibiting a long emission maximum at 1082 nanometers, a high fluorescence quantum yield of 4.3%, and a great photothermal conversion efficiency of 69% in nanoparticles. Leveraging these superior properties, ST-CZ enables cerebrovascular imaging with an advanced resolution of 19.0 micrometers, and the derived multifunctional platform achieves tumor progression–associated vascular remodeling visualization and efficient metastatic tumor ablation via synergistic photothermal immunotherapy. This work provides a robust strategy for developing high-performance NIR-II AIEgens for advanced biomedical applications.