Enzyme-linked immunosorbent assay utilizing thin-layered microfluidics.

Area of Science:

• Biomedical Engineering
• Analytical Chemistry
• Microfluidics

Background:

• Traditional microfluidic enzyme-linked immunosorbent assay (ELISA) using beads faces complex fluidic operations.
• Nanofluidic ELISA offers high sensitivity but uses impractically small sample volumes (fL) for clinical diagnosis.
• Existing methods lack a balance between high surface-to-volume ratio, clinical sample volumes (nL-μL), and operational simplicity.

Purpose of the Study:

• To develop a novel antibody-immobilized, thin-layered microfluidic channel for sensitive and rapid ELISA.
• To adapt nanofluidic ELISA principles to a clinically relevant sample volume.
• To create a bead-free platform for on-site clinical diagnosis.

Main Methods:

• Designed and fabricated a thin-layered microfluidic channel (100 mm width, 103 nm depth) to achieve a high surface-to-volume ratio with a 102 nL reaction volume.
• Incorporated a taper-shaped interface for uniform sample introduction into the high-aspect-ratio channel (width/depth ≈ 200).
• Verified the device's working principle using a standard C-reactive protein solution.

Main Results:

• Demonstrated uniform sample introduction into the thin-layered microfluidic channel.
• Achieved a limit of detection of 34 ng mL⁻¹ for C-reactive protein, comparable to bead-based ELISA.
• The thin-layered ELISA platform successfully maintained a high surface-to-volume ratio.

Conclusions:

• The thin-layered microfluidic channel is a viable bead-free platform for sensitive and rapid ELISA.
• This novel approach bridges the gap between nanofluidic sensitivity and clinical sample volume requirements.
• The developed ELISA platform holds potential for advancing on-site clinical diagnostics and biological research.