Triphenylamine flanked furan-diketopyrrolopyrrole for multi-imaging guided photothermal/photodynamic cancer therapy

The combination of photodynamic therapy (PDT) and photothermal therapy (PTT) is highly desired to improve the cancer phototherapeutic effect. However, most reported multicomponent therapeutic agents need complex preparation processes and must be excited by using multiple light sources. Herein, triphenylamine flanked furan-diketopyrrolopyrrole (FDPP-TPA) with a donor-acceptor-donor structure has been synthesized and used as a sole-component agent for fluorescence, photoacoustic and photothermal imaging guided photodynamic and photothermal synergistic therapy. FDPP-TPA nanoparticles (NPs) obtained by re-precipitation exhibit a high molar extinction coefficient (ϵ = 2.13 (±0.2) × 10⁴ M^-1 cm^-1), excellent photothermal conversion efficiency (η = 47%) and favorable singlet oxygen quantum yield (Φ_Δ(X) = 40%). In vitro, the half-maximal inhibitory concentration (IC₅₀) is 13 μg mL^-1 determined by cytotoxicity assay. And the apoptosis rate is 67.3% according to flow cytometry analysis. In vivo, the tumor can be completely ablated without recurrence, which suggests that FDPP-TPA NPs can generate considerable poisonous singlet oxygen and hyperthermia for tumor treatment.