Salivary Cortisol Detection with a Fully Inkjet-Printed Paper-Based Electrochemical Sensor

Area of Science:

• Analytical Chemistry
• Biosensors
• Materials Science

Background:

• Electrochemical paper-based analytical devices (ePADs) are emerging as low-cost, portable platforms for real-time diagnostics.
• Cortisol detection is crucial for monitoring stress and various physiological conditions.
• Existing methods for cortisol detection can be complex and expensive.

Purpose of the Study:

• To develop a functional, all-inkjet paper-based electrochemical immunosensor for salivary cortisol detection.
• To utilize inkjet printing technology for simplified fabrication and reduced environmental impact.
• To achieve sensitive and specific cortisol detection within the physiological range.

Main Methods:

• Fabrication of ePADs using inkjet-printed gold (Au) ink on paper.
• Covalent immobilization of cortisol monoclonal antibody via electrodeposition of 4-carboxymethylaniline (CMA).
• Ethanolamine passivation to minimize non-specific binding.
• Electrochemical detection of cortisol within the 5-20 ng/mL physiological range.

Main Results:

• The ePAD demonstrated a linear response for cortisol detection in the physiological range.
• High sensitivity was achieved with R² values up to 0.995.
• Excellent specificity was confirmed through interference studies with TNF-α and NT-proBNP.
• Successful fabrication using simplified inkjet printing technology.

Conclusions:

• A novel, inkjet-printed ePAD for salivary cortisol detection has been successfully developed.
• The developed immunosensor offers a low-cost, environmentally friendly, and simplified approach for real-time diagnostics.
• This technology holds promise for accessible point-of-care cortisol monitoring.