Electrochemical detection of cortisol using a molecularly imprinted Au-decorated SiC/β-cyclodextrin nanocomposite sensor in human sweat

Abstract

The developed wearable electrochemical sensing platform demonstrates significant potential for continuous monitoring of cortisol in human sweat, a key biomarker for evaluating stress and fatigue levels in athletic performance. Utilizing a novel Au-decorated nanocomposite functionalized with β-cyclodextrin-assisted molecular recognition sites, this study outlines a systematic fabrication process where SiC nanoparticles are first oxidized and subsequently decorated with gold nanoparticles, achieving an average Au particle diameter of 5.3 ± 1.2 nm to enhance conductivity and electron transfer kinetics. The incorporation of dual amine-terminated β-cyclodextrin not only improves molecular recognition but also facilitates selective cortisol capture, as evidenced by sensitivity improvements to approximately 1.85 μF per ng/mL over a linear range of 5–45 ng/mL and a limit of detection as low as 2.8 ng/mL. Comprehensive electrochemical evaluations, including cyclic voltammetry, confirm the sensor’s ability to reliably distinguish cortisol from potential interferents, yielding selectivity coefficients between 18.3 and 31.0, with reproducibility demonstrated by relative standard deviations below 4.8 %. Real sweat sample analyses using a standard addition method provided a robust calibration curve (R² = 0.993), confirming effective quantification in complex biological matrices typical of athletic environments. Furthermore, the sensor exhibited excellent mechanical resilience, with a capacitance reduction of only 4 % after 20 bending cycles, and maintained stable performance over 30 days, indicating long-term durability suitable for wearable sports applications. This innovative approach integrates material design, surface chemistry, and device engineering to enable rapid, accurate, and noninvasive monitoring of athlete stress levels, offering a promising avenue for real-time physiological tracking during training and competitive performance.