The self-assembly of a hybrid photosensitizer for the synergistically enhanced photodynamic/photothermal therapy

The simultaneous near-infrared (NIR)-absorbed photodynamic therapy (PDT)/photothermal therapy (PTT) has proved to be a promising approach to increase the antitumor efficiency due to their synergistic effect. Herein, a boron dipyrromethene (BODIPY)-based photosensitizer was designed and synthesized for the enhanced synergistic NIR-absorbed PDT/PTT therapy upon NIR light irradiation. In this strategy, a three-dimensional rigid polyhedral oligomeric silsesquioxane (POSS) block was introduced into the Br-BODIPY molecule to alleviate the aggregation of the photosensitizer. The POSS hybrid BODIPY (Br-BODIPY-POSS) was further functionalized with a biocompatible amphiphilic PEG via a facile thiol-ene click reaction, affording Br-BODIPY-POSS-PEG(2000) (BBPP). BBPP can self-assemble into nanoparticles, which maintain a competitive photothermal conversion efficiency (eta(BBPP) = 30.2%) with its counterpart Br-BODIPY-PEG (BBP, eta(BBP) = 34.5%). Significantly, BBPP exhibited a relatively higher oxygen quantum yield (phi(BBPP) = 0.405) than BBP (phi(BBP) = 0.175). The in vitro and in vivo experiments showed that BBPP possessed negligible dark cytotoxicity and a better phototherapeutic outcome than BBP. The proof-of-concept of the POSS hybrid photosensitizer offers guidance for the construction of single-component and PDT/PTT-balanced NIR nanoagents to promote the cancer therapeutic efficacy in the future.

Automated summary

The study designed and synthesized a novel photosensitizer based on boron dipyrromethene (BODIPY) for simultaneous photodynamic therapy (PDT) and photothermal therapy (PTT), with a synergistic effect to enhance the antitumor efficiency. The hybrid photosensitizer showed improved phototherapeutic outcome compared to its counterpart, offering guidance for the development of balanced NIR nanoagents for cancer therapeutic efficacy in the future.