Spontaneous immobilization of single atom in Nb2CTx MXene as excellent nanozyme for detecting and preventing gastric mucosal injury.

Early diagnosis and treatment of gastric mucosal injury is crucial to prevent further gastritis and even canceration. As an efficient biocatalyst, single-atom nanozyme (SAzyme) is proposed to be an ideal candidate for the construction of multifunctional platforms. Nevertheless, SAzyme still faces challenges in detecting and treating diseases due to the complexity of preparation methods, limitations of enzyme activity, and undesirable biocompatibility. Specifically, the Nb2CTx MXene with abundant Nb-deficit vacancy defects and high reductive capability can potentially be recognized as an effective support for stabilizing single atoms. Single-atom Pt-immobilized Nb2CTx nanosheet (SA Pt-Nb2CTx) possessing significant glutathione peroxidase (GPx)-like and superoxide dismutase (SOD)-like activities have been synthesized by a simple spontaneous reduction method. Based on the GPx-like activity of SA Pt-Nb2CTx, a simple Fe2+ fluorescence sensor is developed with a detection limit of 1.02 μM. Furthermore, the in vitro experiments reveal the excellent antioxidation capacity of this nanozyme, which effectively alleviates the inflammatory response. Importantly, the self-assembled SA Pt-Nb2CTx possesses a superior protective effect against ethanol-induced gastric mucosal damage, which is mainly related to the enhanced antioxidant and anti-inflammatory effects. Overall, engineered single-atom modified MXene as a multienzyme mimetic provides new insights for the manufacture of single-atom nanozyme and its application in protecting gastrointestinal health.