3차원 환원 그래핀 산화물 나노복합체와 분자 각인 폴리피롤을 이용한 코르티솔의 전기화학적 검출

Abstract

This study aimed to develop a sensitive and selective electrochemical sensor for cortisol detection using a molecularly imprinted polypyrrole (MIPPy) matrix. The sensor was fabricated on a screen-printed carbon electrode by incorporating reduced graphene oxide–carbon nanotube (rGO-CNT) nanocomposites to enhance conductivity and surface area, while Prussian blue (PrB) was embedded within the MIPPy film as an internal redox probe. Fabrication parameters, including the template concentration, polymerization cycles, and template removal conditions, were systematically optimized to generate well-defined molecular recognition sites. Under the optimized conditions, the MIPPy- PrB/rGO-CNT sensor exhibited a logarithmic calibration behavior toward cortisol over the range of 1 nM to 1 M in phosphate-buffered saline (PBS), with a limit of detection of 18.9 nM. This dynamic range covers physiologically relevant cortisol levels reported in human sweat. The sensor showed high analytical sensitivity, acceptable analytical specificity against structurally related steroid hormones, and good inter-electrode reproducibility, with a coefficient of variation of 4.1% for independently fabricated electrodes. The short-term storage stability test demonstrated that the current response retained 91.5% of its initial value after seven days of storage at 4°C. These results indicate that embedding PrB within the MIPPy layer on an rGO-CNT-modified screen-printed carbon electrode is a simple and effective strategy for improving the electrochemical detection of cortisol, at least under buffered conditions. Although the present evaluation was performed in PBS, the proposed platform represents an initial step toward noninvasive cortisol monitoring and may, after further validation in artificial and real biofluids, be extended to wearable stress-assessment and related bioanalytical sensing applications.