Push-pull type meso-ester substituted BODIPY near-infrared dyes as contrast agents for photoacoustic imaging.

A series of push-pull type meso-ester substituted BODIPY dyes 1-4 with intense near-infrared absorption, largely enhanced photoacoustic (PA) activity and excellent photo-stability were synthesized. The impact of the electronic structure on the PA activity was also discussed. Moreover, the in vitro and in vivo PA imaging were investigated, which suggested a passive targeting capacity in the tumor site.