Ultrasensitive cortisol detection using Ag@Au SERS sensor with molecularly imprinted polymers

Rapid and sensitive detection of cortisol, which is essential for diagnosing adrenal and stress-related disorders, has been achieved through the development of a surface-enhanced Raman scattering (SERS) sensor. This sensor integrates molecularly imprinted polymers (MIPs) with silver core-gold shell nanoparticles (Ag@AuNPs) to provide a selective and sensitive means of cortisol detection. By leveraging the surface plasmon resonance (SPR) effect, the sensor is able to amplify SERS signals, while the MIPs offer specific recognition sites for cortisol. Fabricated using a straightforward two-step process that involves chronoamperometry and self-polymerization, the Ag@AuNPs functionalized with MIP (Ag@Au/MIP) sensor is both easy to prepare and highly reproducible. The Ag@AuNPs increases the effective surface area, optimizing the electromagnetic field and significantly boosting the sensor's sensitivity. The sensor demonstrates a strong affinity for cortisol, exhibiting a linear detection range from 100 pM to 0.1 mM and a detection limit as low as 10 pM. Furthermore, it shows excellent specificity against potential interferences and maintains its stability and anti-interference ability in artificial saliva. By providing a rapid, cost-effective, and user-friendly platform for cortisol detection, this Ag@Au/MIP-based SERS sensor holds great promise for clinical diagnosis, health monitoring, and point-of-care testing applications.