High-Activity Multienzyme-Mimicking Copper-Doped Palladium Metallene Nanozyme toward Portable and Sensitive On-Site Colorimetric Assay

As a key technology enabling green and sustainable chemical processes, nanozymes have significantly enhanced their catalytic efficiency and economic viability. Therefore, the development of a higher catalytic activity enzyme mimic to construct a portable and easily sensing strategy for sensitive, rapid, and convenient determination of a specific target is exceedingly elemental for an advanced sensing platform. Herein, we designed and prepared copper-doped palladium metallene (Cu–Pd metallene) with multiple enzyme-like activities for a sensitive colorimetric assay. The relevant kinetic parameters of Cu–Pd metallene with three kinds of enzyme-like activities were evaluated. The Michaelis–Menten constant of laccase mimic and oxidase mimic were calculated to be 0.041 and 0.51 mM, which exhibited high affinity to 2,4-dichlorophenol and 3,3′,5,5′-tetramethylbenzidine in the corresponding system, respectively. Inspired by its high catalytic activity, a simple and portable colorimetric sensing platform based on Cu–Pd metallene was developed to detect and distinguish epinephrine, phenolics, and thiram by UV–vis absorption spectrum and smartphone. Among them, the proposed method can detect epinephrine concentration in the range of 1–15 μg mL^–1 by laccase-like activity, and a calculated reliable limit of detection is 0.18 μg mL^–1. Owing to the inhibitory effect, the colorimetric sensing platform was used to analyze thiram, which presented a concentration range of 10–500 ng mL^–1 and an acceptable detection limit of 4.4 ng mL^–1. Considering the advantages of accuracy and ease of use of Cu–Pd metallene-based colorimetric sensing platform, it has great potential for real-time monitoring of relevant targets in poor areas.