Photoacoustic imaging (PAI) has emerged as an advantageous modality with high resolution and deep tissue penetration. However, its application is limited by the lack of available contrast agents. In this work, we report the synthesis of a naphthalene fused BODIPY dimer Na-BD, and the impact of the electronic structure on the oxidative cyclo-dehydrogenation process was systematically studied. Na-BD exhibited intense NIR absorption, much better photo-stability and higher PA activity compared to commercial ICG dye, which makes it an excellent contrast agent for PAI. Moreover, the in vivo PAI studies based on Na-BD loaded BSA nanoparticles were carried out and they demonstrated a significant passive targeting capacity by exploiting the enhanced permeability and retention effect in the tumor region.

Photothermal therapy has emerged as a promising tool for treatment of diseases such as cancers. Previous photothermal agents have been largely limited to inorganic nanomaterials and conductive polymers that are barely biodegradable, thus raising issues of long-term toxicity for clinical applications. Here we report a new photothermal agent based on colloidal nanoparticles formed by a small-molecular dye, benzo[1,2-c;4,5-c']bis[1,2,5]thiadiazole-4,7-bis(5-(2-ethylhexyl)thiophene). These nanoparticles showed strong near-infrared absorption, robust photostability and high therapeutic efficiency for photothermal treatment of cancer cells.

The proposed method can optimize laser power density, nanoparticle concentration, and exposure time simultaneously with different weights in interstitial PPTT planning for deep seated tumors. It provides flexibility for a clinician to make appropriate planning for individual patients according to their special needs.

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.

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