(Iso)quinoline-Modified Aza-Boron-Dipyrromethenes Near-Infrared-II Fluorescence/Photoacoustic Nanotheranostics for...

NIR-II small-molecule-based bimodal imaging systems accurately unify diagnosis and therapeutics for precision tumor therapy, which is attributed to their easily modifiable structures, high potential biocompatibility. In particular, the highly efficient photodiagnostic agent with high light-to-heat transformation performance and fluorescence/photoacoustic imaging (FLI/PAI) with the range of near-infrared-II (NIR-II; 900 to 1,700 nm) has emerged as a popular research topic. This study reported a series of Aza-boron-dipyrromethenes (Aza-BODIPY) dyes (Aza-A/B/C) with donor-acceptor structure through the introduction of diethylaminobenzene (electron donor) and (iso)quinoline (electron acceptor) into the Aza-BODIPY backbone. Compared to Aza-A/B, the enhanced light trapping ability, the decreased NIR-II fluorescence emission performance, and poor reactive oxygen species generation capacity made Aza-C as an optimal photothermal agent. Through 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethylene glycol)-2000] (DSPE-mPEG₂₀₀₀) capping, the as-prepared Aza-C nanoparticles (Aza-C NPs) showed excellent biocompatibility, super stability, outstanding light-to-heat transformation performance (ƞ = 58.2%), as well as concentration-dependent linear FL/PA signals, which guaranteed that Aza-C NPs could be successfully utilized for NIR-II FLI/PAI-directed efficient photothermal therapy (PTT) of cervical tumor, with high tumor inhibition rates of over 90%. Introducing diethylaminobenzene and (iso)quinoline to Aza-BODIPY backbone help to construct NIR-II Aza-C dye for NIR-II FLI/PAI-directed efficient tumor PTT. This novel approach offers a promising avenue toward the ablation of tumors in deep tissues.