Colloidal gold probe based rapid immunochromatographic strip assay for cortisol

Area of Science:

• Biochemistry
• Analytical Chemistry
• Immunology

Background:

• Cortisol analysis in serum is crucial for diagnosing various endocrine disorders.
• Existing methods for cortisol detection can be time-consuming and expensive.
• There is a need for rapid, user-friendly diagnostic tools for serum cortisol levels.

Purpose of the Study:

• To develop a rapid and semi-quantitative immunochromatographic strip (ICS) test for cortisol analysis in human serum.
• To characterize the synthesized colloidal gold nanoparticles and antigen conjugates.
• To evaluate the performance of the developed ICS test for serum cortisol detection.

Main Methods:

• A competitive assay format was employed using colloidal gold nanoparticles conjugated with a cortisol-BSA antigen (F-3-CMO-ADH-BSA).
• Characterization of gold nanoparticles and conjugates utilized UV-vis spectroscopy, transmission electron microscopy, and atomic force microscopy.
• Anticortisol antibody was immobilized on a nitrocellulose membrane as the test line, with anti-BSA antibody as the control line.

Main Results:

• The immunochromatographic strip (ICS) test demonstrated a lower detection limit of 30 ng/mL for cortisol.
• Visual detection and results were obtained within 10 minutes.
• Analysis of approximately 30 human serum samples validated the test's ability to establish cortisol concentration ranges.

Conclusions:

• The developed immunochromatographic strip (ICS) test is a rapid, economic, and user-friendly method for semi-quantitative cortisol analysis in serum.
• This assay provides a promising alternative for point-of-care or routine clinical settings requiring quick cortisol level assessment.
• The characterized gold nanoparticle-based assay offers efficient cortisol detection with potential for widespread application.