Disposable electrochemical immunosensor for cortisol determination in human saliva

Area of Science:

• Electrochemistry
• Biomarker Detection
• Sensor Technology

Background:

• Cortisol is a key stress hormone, and its salivary concentration correlates with serum levels.
• Accurate measurement of salivary cortisol is crucial for stress assessment.
• Existing methods may require complex sample preparation or specialized equipment.

Purpose of the Study:

• To develop and validate an electrochemical immunosensor for quantifying cortisol in human saliva.
• To assess the sensor's performance within the physiological concentration range.
• To demonstrate the sensor's suitability for practical diagnostic applications.

Main Methods:

• Fabrication of a direct competitive enzyme-linked immunoassay using a cortisol-alkaline phosphatase conjugate.
• Utilization of disposable graphite screen-printed electrodes (SPEs) and square wave voltammetry (SWV) for detection.
• Testing and calibration using buffer and saliva samples, including analysis of matrix effects.

Main Results:

• The immunosensor achieved a limit of detection (LOD) of 1.7 ng/ml and a working range of 0.5-55.1 ng/ml in saliva.
• High recovery rates (92-114%) were observed in spiked saliva samples.
• Strong correlation (0.90) with UHPLC-MS/MS confirmed the sensor's accuracy.

Conclusions:

• The developed electrochemical immunosensor provides a sensitive and accurate method for salivary cortisol determination.
• The sensor effectively overcomes saliva matrix effects, enabling reliable stress marker assessment.
• This technology holds promise for non-invasive, point-of-care diagnostics of cortisol levels.