Mo Single-Atom Nanozyme Anchored to the 2D N-Doped Carbon Film: Catalytic Mechanism, Visual Monitoring of Choline, and Evaluation of Intracellular ROS Generation
Qijun Sun, Xiaoyu Xu, Song Liu, Xinzhao Wu, Chenhui Yin, Meng Wu, Yuxue Chen, Na Niu, Ligang Chen, Fu‐Quan Bai
Abstract
Single-atom nanozymes (SANs) have attracted great attention in constructing devices for instant biosensing due to their excellent stability and atom utilization. Here, Mo atoms were immobilized in 2D nitrogen-doped carbon films by cascade-anchored one-pot pyrolysis to obtain Mo single-atom nanozyme (Mo-SAN) with high atomic loading (4.79 wt %) and peroxidase-like activity. The coordination environment and enzyme-like activity mechanism of Mo-SAN were studied by combining synchrotron radiation and density functional theory. The strong oxophilicity of single-atom Mo makes the catalytic center more capable of transferring electrons to free radicals to selectively generate • OH in the presence of H 2 O 2 . Choline oxidase and Mo-SAN were used as signal opening unit and signal amplification unit, respectively. Combining the portability and visualization functions of smartphone and test strips, a paper-based visual sensing platform was constructed, which can accurately identify choline at a concentration of 0.5–35 μM with a limit of detection as low as 0.12 μM. The recovery of human serum samples was 96.4–102.2%, with an error of less than 5%. Furthermore, the potential of Mo-SAN to efficiently generate toxic • OH in tumor cells was intuitively confirmed. This work provides a technical and theoretical basis for designing highly active SANs and detecting neurological markers.