Organic nanomaterials from self-assembly of BODIPY-benzothiadiazole conjugate for PDT/PTT synergistic therapy

Near-infrared light-induced phototherapy including photothermal therapy (PTT) and photodynamic therapy (PDT) has emerged as a new noninvasive method for cancer treatment owing to the nature of high efficiency and spatiotemporal selectivity. In this study, a new boron-dipyrromethene (BODIPY) molecule (BDP-BT) with donor (D)-receptor (A)-donor (D) structure was designed and successfully synthesized by conjugation of benzothiadiazole (BT) with BODIPY structure. The polyethylene glycol chain (PEG) was modified onto the meso site of BODIPY to improve the hydrophilicity and biocompatibility of the compound. The amphiphilic BDP-BT was then self-assembled into nanoparticles (BDP-BT NPs) with red-shifted absorption and enhanced hydrophilicity. BDP-BT NPs can produce effective reactive oxygen species and local hyperthermia triggered by a single laser. The in vitro experiments revealed that BDP-BT NPs had good biocompatibility and remarkable photocytoxicity. The half maximal inhibitory concentration (IC50) of BDP-BT NPs was valued at 22.17 mu g/mL under 635 nm laser irradiation. Furthermore, BDP-BT NPs can efficiently generate reactive oxygen species (ROS) in the tumor cells under light irradiation. Thus, the as-prepared BDP-BT NPs could be used as promising agents for PDT and PTT synergistic cancer therapy.