Copper Single-Atom Nanozyme Mimicking Galactose Oxidase with Superior Catalytic Activity and Selectivity

Due to the low stability and high cost of some natural enzymes, nanozymes have been developed as enzyme-imitating nanomaterials. Single-atom nanozymes are a class of nanozymes with metal centers that mimic the structure of metal-based natural enzymes. Herein, Cu-N-C single-atom nanozyme (SAN) is synthesized with excellent peroxidase- and enhanced oxidase-like activities to mimic the action of natural galactose oxidase. Cu-SAN demonstrates stereospecific activity akin to that of natural galactose oxidase by oxidizing D-galactose and primary alcohol but not L-Galactose or other carbohydrates. The SAN can catalyze the oxidation of galactose in the presence of oxygen, producing hydrogen peroxide as a sub-product. The produced hydrogen peroxide then oxidizes 3,3 ',5,5 '-tetramethylbenzidine catalyzed by the SAN, yielding the typical blue product. The relationship between absorbance and galactose concentration is linear in the 1-60 mu m range with a detection limit as low as 0.23 mu m. This strategy can be utilized in the diagnosis of galactosemia disorder and detection of galactose in some dairy and other commercial products. DFT calculations clarify the high activity of the Cu sites in the POD-like reaction and explain the selectivity of the Cu-SAN oxidase-like reaction toward D-galactose The study reports the synthesis of a Cu-N-C single-atom nanozyme (SAN) with peroxidase and oxidase-like activities, mimicking natural galactose oxidase. The SAN selectively oxidizes D-galactose, producing H2O2, which catalyzes the TMB colorimetric reaction. This method enables sensitive galactose detection with potential applications in diagnosing galactosemia and analyzing dairy products. DFT calculations explain the high activity and selectivity of the Cu-SAN. image