Engineering aggregates of julolidine-substituted aza-BODIPY nanoparticles for NIR-II photothermal therapy

Near infrared-II (NIR-II) dyes have unique advantages in biomedical applications owing to the powerful ability in penetrating biological tissues. Herein, NIR-II aza-BODIPY dye, QLD-BDP, was developed with julolidine at 1,7-sites and p-dimethylaminophenyl group at 3,5-sites. According to X-ray analysis, QLD-BDP exhibits significant distortion, and this molecule appears a bowl shaped structure. The photothermal conversion efficiency of the self-assembled QLD-BDP nanoparticles (QLD-BDP-NPs) can reach 50.5%, with maximum emission at 998 nm by the aggregate. QLD-BDP-NPs can cause the complete destruction of 4T1 multicellular spheroids (MCSs), indicating a photothermal therapy (PTT) effect.