An acceptor motor-driven electronic donor–acceptor supramolecular scaffold towards imaging-guided tumor therapy

Traditional approaches to accessing near infrared (NIR) photothermal agents mainly focus on synthesis methods. Herein, based on a supramolecular strategy, an electrostatic force-driven electronic donor-acceptor complex is established with 1,4,5,8,9,11-hexaazatriphenylenehexacarbonitrile (HAT-CN) and perylene as the acceptor and donor, respectively. Due to the strong electronic affinity of the acceptor and the opposite electronic properties between them, through-space charge transfer occurs in the assembly, markedly narrowing the energy gap, thereby inducing obvious NIR absorption and benefiting photothermal conversion. More interestingly, the bond stretching vibration is dramatic and sufficient in the acceptor, making it an acceptor motor in the supramolecular complex to further enhance the photothermal properties. As a result, a prompt heating effect by more than 190 °C can be obtained in the powder under 808 nm laser excitation and the photothermal conversion efficiency of the nanoparticles (NPs) reaches as high as 59.4%. Owing to the good photothermal effect, in vitro and in vivo photoacoustic (PA) imaging can be well performed with the NPs. Moreover, the NPs exhibit prominent phototoxicity to kill CT26 cells and ablate tumors in living mice with the photothermal immunomodulatory effect evoked concurrently. The synergetic strategy in this work provides a facile, economical and flexible avenue for designing highly efficient NIR photothermal agents to accelerate practical biomedical applications.