Carrier-free nanodrugs for in vivo NIR bioimaging and chemo-photothermal synergistic therapy

The combination of chemotherapy and photothermal therapy displays improved anti-cancer effects and lower systematic toxicity of a free drug compared with monotherapy. In this study, we designed innovative, carrier-free nanodrugs (PTX/ICG NDs) composed of the chemotherapeutic agent paclitaxel (PTX) and the photosensitizer indocyanine green (ICG) via self-assembly. The nanodrugs not only incorporated two different modalities into one delivery system for combined chemo-photothermal therapy but also enhanced the solubility of PTX without the need for any carrier. The as-prepared PTX/ICG NDs exhibited the merits of a relatively uniform size of 140 +/- 1.4 nm, surface charge of -36 +/- 2.2 mV, and high drug loading content of PTX. The combination strategy exerted a synergistic effect on the cytotoxicity of cancer cells in vitro, which could be attributed to the high cellular uptake and sustained release of PTX. Furthermore, an in vivo study indicated that PTX/ICG NDs showed higher accumulation in the tumor site than free ICG and possessed strong synergistic chemo-photothermal therapy efficacy against tumors in H22 tumor-bearing mice. Taken together, our study demonstrates that PTX/ICG NDs hold promise to become an alternative chemo-photothermal therapy agent to treat cancers.