Promoting the sensitive detection of ethamsylate via a colorimetric sensing platform based on the enhanced oxidase-mimicking activity of ultrathin MnO2 nanosheets

In this work, we present a novel colorimetric sensing platform for the sensitive detection of ethamsylate (ETM) using ultrathin MnO 2 nanosheets with enhanced oxidase-mimicking activity. A facile template-free hydrothermal process was applied to synthesize the MnO 2 nanosheets under mild conditions. The nanosheets exhibited oxidasemimicking activity, facilitating the conversion of TMB into the blue-colored oxTMB in the absence of H 2 O 2 . 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 mu g/mL and a detection limit of 0.156 mu g/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 2 nanosheets to absorb oxygen, producing superoxide radicals (O 2 center dot - ). 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.