Paper-based immunosensor with competitive assay for cortisol detection

Area of Science:

• Biomedical Engineering
• Analytical Chemistry
• Immunosensors

Background:

• Accurate measurement of cortisol, a key stress hormone, is crucial for diagnosing and managing stress-related conditions.
• Existing methods for cortisol detection can be complex and time-consuming.

Purpose of the Study:

• To develop a rapid, simple, and cost-effective paper-based immunosensor for quantifying cortisol levels in serum.
• To provide a visual detection method for screening serum cortisol.

Main Methods:

• Fabrication of a paper-based sensor using wax printing.
• Development of a competitive immunoassay utilizing cortisol-conjugated BSA and anti-cortisol mAb-conjugated gold nanoparticles.
• A two-step procedure involving sample application and washing for visual cortisol determination.

Main Results:

• The immunosensor visually differentiated serum cortisol levels into three ranges: < 25 μg/dL, 25-50 μg/dL, and > 50 μg/dL.
• The limit of detection was determined to be 21.5 μg/dL using image processing.
• The assay demonstrated good recovery and precision, with results correlating well to electrochemiluminescence methods.

Conclusions:

• A novel paper-based immunosensor was successfully developed for serum cortisol detection.
• This device offers a rapid, simple, and visual screening tool for cortisol levels.
• The developed immunosensor has potential applications in the diagnosis and monitoring of stress-related diseases.