Emission-tunable aromatic thiadiazole derivatives based on triphenylimidazole with aggregation-induced emission activity and their application in osteosarcoma imaging.

Aggregation-induced emission (AIE)-active fluorescent probes have emerged as promising tools for in vivo biomarker detection and biological imaging due to their unconventional emission behavior in aggregated state. In this study, we designed novel imidazole-based aggregation-induced emission luminogens (AIEgens), TPIT, featuring a symmetrical donor-π-bridge-acceptor-π-bridge-donor (D-π-A-π-D) backbone. By introducing benzothiadiazole (BT)-derived acceptors with different electron-withdrawing capabilities and steric hindrance, a series of AIEgens (TPIT-B, TPIT-P, TPIT-N) were successfully synthesized, exhibiting tunable emission windows from red (641 nm) to near-infrared (NIR) region (802 nm), typical AIE characteristics, significant Stokes shifts (> 120 nm ) and remarkable reactive oxygen species (ROS) generation efficiency. In further animal experiments, TPIT-N nanoparticles (NPs) achieved high-contrast NIR imaging of osteosarcoma (OS) tissues. Our preliminary findings reveal that the optical performance of TPIT can be facilely modulated to meet specific requirements by rational selection of acceptor cores. This flexible molecular engineering strategy endows TPIT with board potential in medical diagnostics, tumor treatments and other biological applications.