DNA aptamer and gold-nanofiller integrated hybrid hydrogel network for electrochemical detection of salivary cortisol

Quantitative detection of salivary cortisol enables the non-invasive assessment of physiological stress. However, detecting low concentrations of cortisol is challenging due to the matrix effect caused by the salivary proteins and mucin. Herein, we combine the advantages of aptamer-based electrochemical sensing platform with hybrid hydrogel network for detecting salivary cortisol levels. While the aptamer is conjugated with the redox probe for signal generation, the hydrogel network is integrated with nanofiller (gold nanocubes) for improving the electrical conductivity. The hydrophilic properties of hybrid hydrogel network helped in reducing the matrix effect and enabled the detection of physiologically relevant cortisol concentrations (0.1–50 ng/mL) in human saliva samples (n = 6). The analytical response of the electrochemical sensing platform towards salivary cortisol levels was validated using enzyme-linked immunosorbent assay (ELISA) method.