Copper-based nanozymes for environmental analytical applications: A review

The analysis and detection of pollutants is one of the important steps in solving environmental problems. Natural enzymes, as efficient catalysts produced in living organisms, can be applied to the detection and sensing of pollutants through their mediated enzymatic reactions. However, the poor environmental stability, complex purification techniques, and high costs of natural enzymes have limited their large-scale application in environmental analysis. Nanozymes, as a class of nanomaterials with enzyme-like activity, are characterized by high catalytic activity, good stability, low cost, and easy production and preparation. Most nanozymes use transition metals as catalytic active sites. Since copper has multiple oxidation states, nanozymes with copper as the active center typically exhibit multiple activities, particularly some copper-based nanozymes that possess oxidase-like activity, whose catalytic action relies on oxygen. This characteristic has enabled their broader application in environmental analysis (e.g., rapid detection and identification of environmental pollutants). This review discusses the classification of enzyme-like activities of copper-based nanozymes and their design strategies, composition types, and various applications in the field of environmental analysis (rapid detection and identification of environmental pollutants) based mainly on the research of copper-based nanozymes for the analysis of environmental pollutants in the last three years, and summarizes the current status of copper-based nanozymes in environmental analysis (their effectiveness in detecting and identifying environmental pollutants), challenges (low sensitivity, poor selectivity, lack of rational design), and future trends (integration with electrocatalysis, molecular imprinting technology, and rational design based on target substance characteristics). We link the activity of copper-based nanozymes with their corresponding design strategies and discuss approaches to yield copper-based nanozymes with a range of activities. The interactions between the target substances and the signal output generated by copper-based nanozymes are summarized. We believe this will facilitate the further development of practical applications for copper-based nanozymes in environmental analysis.