A microfluidic technique to estimate antigen expression on particles.

Area of Science:

• Biomedical Engineering
• Cell Biology
• Analytical Chemistry

Background:

• Antigen expression is a key biomarker for cell analysis and disease diagnosis.
• Current methods like flow cytometry are unsuitable for point-of-care applications due to cost and complex sample preparation.
• There is a need for automated, miniaturized assays for rapid clinical decisions and broader research use.

Purpose of the Study:

• To present a novel microfluidic device for measuring antigen expression on cells.
• To demonstrate the device's functionality using a biotin-neutravidin binding pair.
• To establish a method for quantifying antigen expression analogous to protein levels on cell surfaces.

Main Methods:

• Fabrication of a polydimethylsiloxane (PDMS) microfluidic channel with functionalized pillars.
• Experimental and computational analysis of bead capture dynamics under varying shear stress and collision angles.
• Derivation of the probability of capture per collision (ε) based on bead surface density (m) and capture fraction (γ).

Main Results:

• Bead capture location on pillars is influenced by shear stress and collision angle.
• The fraction of captured beads (γ) is dependent on biotin surface density (m).
• The probability of capture per collision (ε) shows a linear relationship with biotin surface density (m), mimicking antigen expression levels.

Conclusions:

• The developed microfluidic device effectively quantifies antigen expression using a bead-based model.
• This technology has the potential to be adapted for cell-based assays, enabling rapid point-of-care antigen detection.
• The findings support the development of new diagnostic tools for clinical settings and basic biological research.