Copper Nanoparticle/N-Doped Ti₃C₂T_x MXene Hybrids with Enhanced Peroxidase-like Activity for Colorimetric Glucose Sensing

As a low-cost support, MXenes have attracted more and more attention in developing nanoenzymes with enhanced peroxidase- or oxidase-like activity. In this paper, we report a simple way to synthesize a N-doped Ti3C2Tx MXene, which provides a support platform for developing MXene-based nanozymes with an attractive structure and performance. By anchoring copper nanoparticles on N-doped Ti3C2Tx Cu nanoparticles, Cu nanoparticles (NPs)/N-doped Ti3C2Tx with satisfactory structural stability was prepared, displaying a synergistic effect and enhanced peroxidase-like activity. The superior peroxidase-like activity was confirmed by the oxidation kinetics of 3,3′,5,5′-tetramethylbenzidine (TMB) and density functional theory calculations. The characteristics of peroxidase-like nanozymes have promoted the development of colorimetric biosensors to evaluate the performance of Cu NPs/N-doped Ti3C2Tx. As expected, the nanozyme exhibits gratifying sensitivity, high selectivity, a low detection limit of 5 μM, and practicability in the detection of serum samples. Remarkably, the Cu NPs/N-doped Ti3C2Tx has remarkable stability and maintains its peroxidase-like activity after 1 month of storage. This work has laid a solid foundation for guiding the design of metal NPs/nonmetal-doped MXenes with outstanding peroxidase-like activity and expanding their application in biosensors.