A novel ternary Ag-Cu2O/Ti3C2 heterostructure with high peroxidase-like activity for on-site colorimetric detection of galactose

In view of galactose as an essential marker in the diagnosis of galactosemia that affects newborns, a rapid and effective method for galactose detection is necessary. Herein, we provide a facile colorimetric biosensor for galactose detection by combining the ternary Ag-Cu2O/Ti3C2 heterostructure and galactose oxidase (Gal Ox). A series of tests showed the Ag-Cu2O/Ti3C2 nanozyme prepared by depositing truncated octahedral Ag-Cu2O on single-layer Ti3C2 nanosheets in a simple one-pot water bath procedure exhibited moderately higher peroxidase-like activity than either pure Ti3C2 nanosheets or binary Cu2O/Ti3C2. Gal Ox can catalyze the oxidation of galactose to yield H2O2, and Ag-Cu2O/Ti3C2 nanocomposites subsequently trigger a reaction between H2O2 and 3,3′,5,5′-tetramethylbenzidine (TMB), accompanied by a significant increase in absorbance at 652 nm. Under optimal conditions, the linear range of galactose is 30–600 μM, with a detection limit of 0.99 μM. Galactose was successfully detected in human serum using the stated method in agreement well with hospital results. Furthermore, we used the designed system to construct portable agarose gel-based assay kits and realized a linear detection ranging from 50 to 500 μM, demonstrating the feasibility of the on-site detection of galactose semiquantitatively and visually in human serum in conjunction with the ImageJ program.