Rational design of amphiphilic BODIPY-based photosensitizers for multimodal imaging-guided phototherapy

The design of effcient photosensitisers for cancer theranostics is of great importance, especially for multimodal-imaging-guided synergistic therapy. The key to achieving accurate imaging-guided phototherapy is to balance the energy distribution between fluorescence imaging, photodynamic therapy (PDT) and photothermal therapy (PTT). Herein, we propose a strategy of introducing hydrophilic chains and halogen atoms in boron dipyrromethene (BODIPY), which can self-assemble into J-aggregate nano-micelles in water with free BODIPY molecules in the cavity, enabling both imaging and multiple therapeutics. Remarkably, the degree of J-aggregation of the nanoparticles (NPs) varies under the influence of the steric effects of the 3,5-position group of BODIPY. In particular, BDPN NPs with suitable nano-size, strong NIR-absorption, applicable fluorescence quantum yield (Φf = 3.0%), satisfactory photothermal conversion efficiency (PCE = 54.9%) and favorable singlet oxygen quantum yield (ΦΔ = 40.76%) were proved to completely destroy 4T1 tumors under 808 nm laser irradiation without significant dark cytotoxicity, enabling synergistic PDT/PTT guided by fluorescence/photothermal/photoacoustic imaging. This study provides an emerging strategy for cancer therapy and a novel idea for the future development of new efficient photosensitizers.