Recent Advances in Combination of Copper Chalcogenide-Based Photothermal and Reactive Oxygen Species-Related Therapies

In recent times, the copper chalcogenide (Cu2-xE, E = S, Se, Te, 0 <= x <= 1)-based nanomaterials have emerged as potent photothermal agents for photothermal therapy (PTT) because of their advantageous features, such as the low cost, reduced toxicity, biodegradability, and strong absorption of near-infrared (NIR) light in a relatively wide range of wavelength. Nevertheless, the applicability of Cu2-xE-based PTT is limited because of its inadequate photothermal conversion efficiency, as well as insufficient destruction of the tumor area unexposed to the NIR laser. Fortunately, Cu2-xE nanomaterials also act as photosensitizers or Fenton-reaction catalysts to produce reactive oxygen species (ROS), referring to ROS-related therapy (RRT), which could further eradicate cancer cells to address the aforementioned limitations of PTT. Moreover, PTT improves RRT based on photodynamic therapy (PDT), sonodynamic therapy (SDT), chemodynamic therapy (CDT), and radiotherapy (RT) in different ways. Inspired by these facts, integrating Cu2-xE-based PTT with RRT into a single nanoplatform seems an ideal strategy to achieve synergistically therapeutic effects for cancer treatment. Herein, we discuss the synergetic mechanisms, composition, and performances of recent nanoplatforms for the combination of Cu2-xE-based PTT and RRT. In addition, we give a brief overview on some specific strategies for the further improvement of Cu2-xE-based PTT and RRT combined cancer treatment to enable the complete eradication of cancer cells, such as realizing the imaging-guided synergistic therapy, promoting deep tumor penetration of the nanosystems, and boosting O-2 or H2O2 in the tumor microenvironment. Finally, we summarize with intriguing perspectives, focusing on the future tendencies for their clinical application.