Disposable immunosensor for cortisol using functionalized magnetic particles

Area of Science:

• Electrochemistry
• Biosensors
• Immunochemistry

Background:

• Cortisol analysis is crucial for diagnosing various endocrine disorders.
• Existing methods for cortisol detection can be complex and time-consuming.
• Development of sensitive and rapid detection platforms is needed.

Purpose of the Study:

• To develop a novel electrochemical immunosensor for sensitive and selective cortisol determination.
• To utilize screen-printed carbon electrodes and functionalized magnetic particles for enhanced detection.
• To validate the immunosensor's performance in real human serum samples.

Main Methods:

• Immobilization of anti-cortisol antibody onto protein A-modified magnetic particles.
• Direct competitive immunoassay with alkaline phosphatase (AP)-labeled cortisol antigen.
• Electrochemical detection using differential pulse voltammetry (DPV) of AP substrate.
• Optimization of immunosensor preparation and electrochemical detection parameters.

Main Results:

• Achieved a linear detection range for cortisol from 5.0 x 10(-3) to 150 ng mL(-1) with high correlation (r = 0.993).
• Demonstrated a low limit of detection (LOD) of 3.5 pg mL(-1).
• Exhibited high selectivity for cortisol against related corticosteroid compounds and validated performance in certified human sera.

Conclusions:

• The developed electrochemical immunosensor offers a highly sensitive and selective platform for cortisol quantification.
• The use of magnetic particles and screen-printed electrodes simplifies the assay procedure.
• This method shows significant potential for routine clinical analysis of cortisol in biological samples.