Acceptor-engineering tailored type-I photosensitizer with aggregation-induced NIR-II emission for cancer multimodal phototheranostics

Exploration of single molecular species synchronously featured by long excitation/emission wavelength, accurate diagnosis, and effective therapy, remains supremely appealing to implement high-performance cancer phototheranostics. However, those previously established phototheranostic agents are undiversified and stereotyped in terms of structural skeleton, and generally exhibit insufficient phototheranostic outcomes. Herein, we innovatively utilized indanone-condensed thiadiazolo[3,4-g]quinoxaline (ITQ) as electron acceptor to construct novel photosensitizer with second near-infrared (NIR-II) emission. Experimental study and theoretical calculation demonstrated that comparing with the counterparts constituting by widely employed NIR-II building block benzobisthiadiazole (BBTD) and 6,7-diphenylthiadiazoloquinoxaline (DPTQ), ITQ-based photosensitizer (TITQ) showed superior aggregation-induced emission (AIE) characteristics, much stronger type-I reactive oxygen species (ROS) production, and prominent photothermal conversion capacity. Furthermore, TITQ nanoparticles with excellent biocompatibility were capable of effectively accumulating in the tumor site and visualizing tumor through fluorescence-photoacoustic-photothermal trimodal imaging with highly spatiotemporal resolution, and completely eliminating tumor by type-I photodynamic-photothermal therapy.