Utilization of Nonradiative Excited-State Dissipation for Promoted Phototheranostics Based on an AIE-Active Type I ROS Generator

As for effective multimodal phototheranostic AIEgens, it is important to find strategies for manipulating photophysical dissipation to achieve optimized performance. Herein, a “all-in-one” phototheranostic AIEgen, (E)-3-(2-(2-(5-(4-(diphenylamino)phenyl)thiophen-2-yl)vinyl)naphtho[1,2-d]thiazol-1-ium-1-yl)propane-1-sulfonate (NS-STPA) was constructed by a rigid coplanar grafting flexible rotor. NS-STPA nanoparticles (NPs) exhibited NIR fluorescent luminescence (FL) with φFL 2.78%. Upon 660 nm irradiation, the high photothermal conversion efficiency (39.01%) and effective reactive oxygen species (ROS) generation (5.28 times to Ce6) indicated the nonradiative decays are valuable in phototherapy. High •OH outputs showed NS-STPA NPs were outstanding type I ROS generators. The twisted D–A structure induced a large spin–orbit coupling (SOC), and insertion of thiophene decreased the S1–T1 energy gap (ΔEST). The nanoaggregate prolonged the triplet-state lifetime (τT). These all facilitate the intersystem crossing (ISC) for NS-STPA NPs. The photoinduced electron transfer resulted in •O2– and then •OH generation. In vivo evaluation indicated the promising application of NS-STPA NPs in FL and photothermal dual imaging-guided synergistic photodynamic and photothermal therapies.