Accurate cortisol monitoring is essential for stress assessment and health management, yet reliable quantification remains challenging because signal fluctuations and matrix effects can compromise the performance of conventional single-mode immunosensors. Herein, we developed a fluorescence-colorimetric (FL-CL) dual-modal immunosensor based on a CuMOF-PEI@AuNPs@HRP (CPA) immunoreceptor for cortisol determination. The integrated sensing architecture generates correlated fluorescence and colorimetric responses from the same recognition event, which are combined through a normalized dual-signal output to improve calibration reliability. Under optimized conditions, the proposed sensor exhibited a detection limit of 0.22 ng/mL and a linear range of 3.1-200 ng/mL, covering physiologically relevant cortisol concentrations in saliva. Compared with single-modal assays and commercial kits, the proposed platform demonstrates enhanced sensitivity, improved correlation, good stability, and batch reproducibility. By integrating signal amplification, dual-modal readout, and simplified immunoreceptor fabrication within a single sensing platform, this work provides a reliable strategy for cortisol monitoring and offers potential for extension to other biomarker detection systems.
