Organic Nanomaterials Based on Aza-Boron Dipyrromethene with Aggregation-Induced Emission for NIR-II Fluorescence Imaging-Guided Photothermal Therapy

Advancing stable and biocompatible photothermal agents has emerged as a pivotal focus in the field of tumor photothermal treatment. Here, we synthesized two aza-boron-dipyrromethene (Aza-BODIPY) derivatives (NN-BP and TP-BP) with donor–acceptor–donor (D-A-D) structures, which exhibited robust near-infrared (NIR) absorption. Following encapsulation within the amphiphilic polymer (DSPEG-PEG2000), both NN-BP and TP-BP underwent self-assembly into nanoparticles (NN-BP NPs and TP-BP NPs), which displayed emission extended to near-infrared II regions (1000 nm). In vitro studies revealed that the two nanoparticles showed outstanding biocompatibility and a strong photothermal effect. These properties allowed the NPs to successfully destroy tumor cells under laser exposure. The TP-BP molecules featured typical AIE structure characteristics because of the triphenylamine group on both sides. After administration of TP-BP NP through the tail vein, NIR-II fluorescence imaging was realized in vivo with 4T1 tumor-bearing mice as a model. Compared with other treatment groups, the combination of TP-BP NPs and laser irradiation exhibited high tumor suppression efficiency without observable side effects. Altogether, TP-BP NPs achieved promising NIR-II imaging and local photothermal treatment of tumors, which opened an avenue for the development of phototheranostics.