Near-infrared heptamethine cyanine dye-based nanoscale coordination polymers with intrinsic nucleus-targeting for low temperature photothermal therapy

Effective photothermal therapy (PTT) under low temperature (< 50 °C) and power density (< 0.4 W/cm²) avoiding the damage of skin and normal organs. Here, we report a novel heptamethine cyanine dye-based nanoscale coordination polymer (NCP), Hf-HI-4COOH, as an exceptionally effective photosensitizer for nucleus-targeting low temperature PTT. Hf-HI-4COOH shows strong near-infrared absorption and high photothermal conversion efficiency (39.51 %). Further, it exhibits intrinsic nucleus-targeting property and cell inhibition under low power density in vitro. Moreover, the long blood circulation, high tumor accumulation, and nucleus-targeting contribute to significant inhibition of breast tumors in tumor-bearing mice under low temperature (48 °C) and power density (0.3 W/cm²) without obvious toxicity. In general, we establish a nucleus-targeting Hf-HI-4COOH for enhanced PTT with low temperature and power density.