High efficiency ring-lens supercritical angle fluorescence (SAF) detection for optimum bioassay performance

Area of Science:

• Biotechnology
• Optical Engineering
• Materials Science

Background:

• Supercritical angle fluorescence (SAF) offers sensitive detection but is often limited by optical losses.
• Existing biochip platforms may lack integration capabilities or cost-effectiveness for widespread use.

Purpose of the Study:

• To develop and validate a polymer biochip with embedded optics for efficient SAF detection.
• To demonstrate the platform's potential for sensitive and rapid point-of-care diagnostic applications.

Main Methods:

• Fabrication of a polymer biochip with integrated spherical and aspherical optical elements.
• Chemical functionalization of the biochip surface for biomolecule immobilization.
• Utilizing a confocal optical setup with an ellipsoidal mirror for SAF light collection.
• Detection of SAF signals using a photon-counting detector.

Main Results:

• The biochip enables SAF detection without substrate-induced losses.
• Successful validation with direct binding DNA and human IgG assays.
• Achieved low limits of detection: 10 pM for DNA and 10 pg/ml for human IgG.

Conclusions:

• The developed optical biochip platform is robust, low-cost, and disposable.
• It offers a sensitive and rapid method for point-of-care testing.
• The platform shows significant potential for future diagnostic devices and lab-on-a-chip systems.