Cisplatin-appended BODIPY for near infrared II fluorescent and photoacoustic imaging-guided synergistic phototherapy and chemotherapy of cancer

Combining phototherapy and chemotherapy has been considered a promising modality for cancer therapy due to their synergistic effect. Herein, we developed three D-π-A-structured boron dipyrromethenes (BODIPYs) (named as B-B, B-C, and B-C-Pt). Due to their enlarged π-conjugated structure and high intramolecular charge transfer effect, the synthesized BODIPYs had photothermal conversion capability, and their absorption and fluorescence spectra were red-shifted. The cisplatin-appended BODIPY (B-C-Pt) exhibited good singlet oxygen (1O2) generation ability and near infrared (NIR) absorption and fluorescence (λAbs = 748 nm, λEm = 947 nm). After being encapsulated by distearoyl phosphoethanolamine polyethyleneglycol 2000 (DSPE-PEG-2000), which could inhibit the H-aggregation of B-C-Pt, the absorption and fluorescence of the obtained B-C-Pt nanoparticles (NPs) were red-shifted to 762 and 985 nm, respectively. The 1O2 quantum yield and photothermal conversion efficiency of the B-C-Pt NPs were 4.0% and 40.6%, respectively. Moreover, B-C-Pt NPs had chemotherapeutic efficacy due to the presence of cisplatin. In vitro and in vivo studies further demonstrated that B-C-Pt NPs had synergistic therapeutic efficacy. Together, B-C-Pt NPs could be employed in NIR II fluorescent and photoacoustic imaging-guided synergistic phototherapy and chemotherapy for cancer treatment.