Wearable electrochemical aptasensor based on MXene@gold nanoparticles for non-invasive sweat cortisol detection

Chronic stress exerts detrimental effects on both physical and mental wellbeing, thereby necessitating the quantitative and real-time monitoring of stress biomarkers, such as cortisol. To address this, a non-invasive, wearable electrochemical aptasensor based on MXene and gold nanoparticles (Mxene/AuNPs) modified screen-printed electrodes (SPEs) is proposed to detect cortisol in human sweat. Conformationally altered aptamers, with methylene blue (MB) as an electrochemical indicator, are linked to AuNPs via gold-sulfur bonds to capture cortisol. Mxene/AuNPs not only increase the specific surface area of the working electrode but also facilitate the immobilization of the aptamer. Moreover, an integrated microfluidic sampler is integrated with this aptasensor to ensure efficient sweat collection, which could effectively prevent sweat evaporation and contamination. Finally, the performance of this aptasensor is evaluated through the differential pulse voltammetry (DPV) technique, exhibiting high specificity ranging from 0.5 to 500 ng/ml (1.38-1379 nM) with a low detection limit of 0.1 ng/ml. This work demonstrates a practical strategy for developing cost-effective and scalable wearable sensors for sweat-based biomarker detection.