Multifunctional UCNPs@PDA-ICG nanocomposites for upconversion imaging and combined photothermal/photodynamic therapy with enhanced antitumor efficacy

:Yb nanoparticles (UCNPs) capable of loading indocyanine green (ICG) molecules via electrostatic adsorption, hydrophobic interaction and π-π stacking were successfully designed and synthesized (UCNPs@PDA-ICG, denoted as UPI) for upconversion imaging and combined photothermal/photodynamic therapy (PTT/PDT) with enhanced antitumor efficacy. We have found that ICG in this novel anticancer nanoplatform can be triggered impressively by 808-nm irradiation to produce both a photothermal effect and cytotoxic reactive oxygen species (ROS), thus achieving a good PTT/PDT synergistic effect. Notably, compared with free ICG molecules, UPI nanocomposites show much higher photostability and thermal stability. Both in vitro and in vivo experiments show that the as-obtained UPI can ablate cancer cells effectively with 808-nm irradiation, revealing their great potential as a NIR-mediated dual-modal therapeutic platform. Meanwhile, the core of UCNPs can be used for UCL imaging. All these results demonstrate great potentiality of UPI as a novel type of theranostic agent for the treatment of tumors.