Outstanding ROS generation ability and the mechanism of MXene quantum dots

Abstract

MXene quantum dots (MQDs) stand out with biocompatibility, biodegradability, and unparalleled optical absorption properties, offering compelling potential in producing exogenous reactive oxygen species (ROS) to treat tumor or bacterial infections. However, there is a gap in the comprehensive research of MQDs in ROS generation. In this study, three representative MQDs (Ti₃C₂ QDs, Ti₂C QDs, and V₂C QDs) were synthesized by the hydrothermal method and their ROS-generating ability and mechanism were thoroughly investigated. 3,3′,5,5′-Tetramethylbenzidine and ascorbic acid assays verified that the three MQDs possessed high ROS generation levels under UV 365 nm irradiation. Then, ESR spectroscopy and the Trinder reaction identified the specific types of ROS generated, including hydroxyl radicals (·OH), singlet oxygen (¹O₂), superoxide radicals (O₂˙⁻), and hydrogen peroxide (H₂O₂). In addition, UPS, PL spectroscopy and electrochemical analyses further investigated the origin of ROS. MQDs' excellent ROS generation capability can be attributed to their unique energy band structure, high carrier separation efficiency and excellent electron transfer ability. This work demonstrates that MQDs, with their ability to efficiently generate multiple types of ROS under UV irradiation, are promising pro-oxidant candidates and pave the way for various related biological applications.