Oxygen-terminated few-layered Ti3C2Tx MXene nanosheets as peroxidase-mimic nanozyme for colorimetric detection of kanamycin

Nanomaterials-based bioinspired enzyme mimics are gaining increased attention as alternatives to biocatalysts. Herein, we report synthesizing oxygen-terminated few-layered titanium-based MXene nanosheets (OFL-Ti-MN). OFL-Ti-MN possesses horseradish peroxidase (HRP) activity in catalyzing the oxidation of colorless 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of hydrogen peroxide (H2O2), which turns the solution color bluish-green. The solution color fades quickly when kanamycin (KAN) is added to this system. This reaction indicates that KAN can prevent color change in the OFL-Ti-MN/TMB-H2O2 system. Based on this strategy, we developed an OFL-Ti-MN-based colorimetric sensor to detect and quantify KAN. The sensor exhibited a dynamic range from 15.28 nM to 46.14 μM and a calculated limit of detection (LOD) of 15.28 nM. From the insight gained from the peroxidase-mimic property of OFL-Ti-MN, we proposed a mechanism for the inhibition effect of KAN on peroxidase and peroxidase-mimic enzymes. The proposed mechanism can potentially help elucidate the reasons for the antibacterial function of KAN and its side effects in humans.