Nanobiosensor Based on Catalytic Palladium Nanoclusters and Oxidases for Bianalyte Electrochemical Determination: Glucose and Ethanol in Sweat

Monitoring metabolites through non-invasive methods is revolutionizing clinical analysis, with decentralized and faster tests. Sweat, a readily available biological fluid that requires non-invasive and simple procedures, is emerging as a valuable source of key biomarkers, such as glucose and ethanol. In this work, an enzymatic nanobiosensor for simultaneous determination of glucose and ethanol in sweat samples has been developed. The electrochemical platform consists of two working electrodes onto which Pd nanoclusters (PdNCs) with catalytic activity for the oxygen reduction reaction were deposited. Additionally, each WE was modified either with glucose oxidase (GOx) or alcohol oxidase (AOx). Thus, the simultaneous quantification of both analytes, glucose and ethanol, was performed thanks to the localized decrease in the concentration of dissolved O₂ produced at each WE by the oxidase enzymes. This resulted in a reduction of the current density measured by cyclic voltammetry. Sweat samples were collected using a polyamide membrane that permits extremely rapid analysis without the need for any external solution or sample pretreatment, making the method user-friendly and well-suited for self-analysis. The results revealed the capability of the nanobiosensor for determining the increase in the level of both analytes in sweat after the consumption of alcoholic beverages and energy drinks.