Immunosensor with fluid control mechanism for salivary cortisol analysis.

Area of Science:

• Biomedical Engineering
• Analytical Chemistry
• Biosensor Technology

Background:

• Cortisol analysis is crucial for diagnosing stress-related disorders.
• Current methods for salivary cortisol measurement can be invasive or time-consuming.
• There is a need for rapid, noninvasive, and point-of-care cortisol detection methods.

Purpose of the Study:

• To develop and validate a novel cortisol immunosensor for quantitative, noninvasive analysis of salivary cortisol.
• To integrate a fluid control mechanism for efficient vertical and lateral flow within the immunosensor.
• To assess the performance and reliability of the developed immunosensor for point-of-care applications.

Main Methods:

• A competitive immunoassay format was employed using a glucose oxidase (GOD)-labeled cortisol conjugate.
• Detected current was measured, showing an inverse relationship with sample cortisol concentration.
• The immunosensor incorporated a unique fluid control system for optimized sample handling.

Main Results:

• The cortisol immunosensor demonstrated high accuracy with R(2)=0.98 and CV=14% for salivary cortisol concentrations (0.1-10 ng/ml).
• Measurements were completed within 35 minutes, and the sensor showed reusability.
• Results closely correlated with the commercial ELISA method (R(2)=0.92).

Conclusions:

• The developed cortisol immunosensor offers a promising solution for noninvasive, on-site, and quantitative measurement of salivary cortisol.
• The biosensor's ease of use and accuracy support its potential for point-of-care diagnostics.
• This technology could significantly improve the monitoring of human salivary cortisol levels in clinical settings.