Promoting the sensitive detection of ethamsylate via a colorimetric sensing platform based on the enhanced oxidase-mimicking activity of ultrathin MnO nanosheets.

In this work, we present a novel colorimetric sensing platform for the sensitive detection of ethamsylate (ETM) usingultrathin MnO nanosheets with enhancedoxidase-mimicking activity. A facile template-free hydrothermal process was applied to synthesize the MnO nanosheets under mild conditions. The nanosheets exhibited oxidase-mimicking activity, facilitating the conversion of TMB into the blue-colored oxTMB in the absence of HO. However, the presence of ETM inhibited this activity, resulting in the conversion of oxTMB back to colorless TMB and a substantial decrease in the blue color intensity. The colorimetric response exhibited a linear relationship with ETM concentration over the range of 0.5 to 10.0 µg/mL and a detection limit of 0.156 µg/mL. To further elucidate the underlying mechanism, we performed extensive characterization and kinetic experiments. The findings demonstrated that this unique property is attributed to the remarkable capacity of the MnO nanosheets to absorb oxygen, producing superoxide radicals (O). The oxidase-mimicking activity of the nanosheets was further confirmed by the reaction kinetics, following Michaelis-Menten's behavior. Moreover, the applicability of the sensing platform was assessed by determining ETM concentrations in various real samples (different pharmaceuticals, human plasma, and environmental water). The well-established platform demonstrates the prospective role that nanomaterials-based sensing platforms may play in clinical diagnostics, pharmaceutical analysis, and other relevant fields.