(360a) Enhanced Sensitivity in Cortisol Detection Using ?eta Cyclodextrin Biosensor: Integrating Automated Flow Cell System with EIS

This study aims to assess the efficacy of a βCD biosensor in non-redox mediated electrochemical impedance spectroscopy (EIS) for measuring cortisol levels in PBS and urine. Cortisol presents a unique challenge in electrochemical sensing, being electrically neutral at physiological pH and lacking electrochemical activity, necessitating innovative strategies. Because cortisol plays a crucial role in controlling many important body functions like immunity, metabolism, and heart health, there is a pressing need for accurate detection methods. We improve our methodology based on previous successful experiments conducted with static cells [1] by converting it to automated flow cell system.

In this study, we focus on measuring different variables of EIS across various frequencies to optimize sensitivity of the sensor. Surface modification involves grafting diazonium salt onto a glassy carbon electrode, followed by carboxylic group conjugation using EDC/NHS chemistry. Further modification with polypropylene glycol (PPG) precedes cyclodextrin loading onto the surface. Characterization of the surface is carried out through EIS to characterize the polymer-modified surface state in analyte detection.

Our results demonstrate remarkable sensitivity to cortisol, even at low concentrations, representing a substantial improvement over static cell method [1]. Additionally, we are testing the stability, aiming for long-term stable automated system for analyte detection. These finding highlight the clinical potential of our biosensor before we transition into monitoring cortisol levels for various health conditions.

Research supported by New Hampshire- INBRE through an Institutional Development Award (IDeA), P20GM103506, from the National Institute of General Medical Sciences of the NIH. Support was also provided by a National Science Foundation EPSCoR award (#2119237), BIO-SENS.

[1] Z. Panahi, T. Ren, and J. M. Halpern, “Nanostructured Cyclodextrin-Mediated Surface for Capacitive Determination of Cortisol in Multiple Biofluids,” ACS Appl. Mater. Interfaces, vol. 14, no. 37, pp. 42374–42387, Sep. 2022, doi: 10.1021/acsami.2c07701.