Second Near-Infrared Photothermal Therapy with Superior Penetrability through Skin Tissues

Abstract

Photothermal therapy (PTT) triggered by second near-infrared (NIR-II) light (1000-1400 nm) has shown great potential in tumor ablation because of its good tissue penetrability. However, NIR-II PTT still cannot treat tumors underneath skin because of the light scattering effect of skin components. This research aims to promote the NIR-II penetrability of skin tissue by weakening the light scattering effect from the refractive index inhomogeneity among skin constituents. This strategy allows for a notable improvement of NIR-II transmittance in vivo from 30% to 70% through mouse skin. In animal experiments, the local temperature of tumor tissue in the experiment group is 14.1 °C higher than that in the control group due to superior tissue penetration, which is thus responsible for the excellent therapeutic effects of complete ablation without any reoccurrence. Such a strategy not only achieves a perfect PTT effect, but also benefits the development of other light-related biological applications.