Homogeneous agglutination assay based on micro-chip sheathless flow cytometry.

Area of Science:

• Biomedical Engineering
• Analytical Chemistry
• Microfluidics

Background:

• Homogeneous assays offer advantages like no washing steps, enabling robust protocols and point-of-care applications.
• Simplifying detection strategies and reducing reagent use are key goals for assay development.
• Microfluidic platforms are increasingly utilized for developing compact and efficient diagnostic tools.

Purpose of the Study:

• To develop a simplified homogeneous bead-agglutination assay.
• To integrate this assay with a micro-chip sheathless flow cytometric device.
• To assess the sensitivity and applicability of the developed method for analyte detection.

Main Methods:

• A homogeneous bead-agglutination assay was designed using capture-probe conjugated beads.
• Reaction mixtures were analyzed using a micro-chip sheathless flow cytometric device.
• Analyte concentration was determined by quantifying the ratio of aggregated beads (monomers) to non-aggregated beads (aggregates) via forward scattering.

Main Results:

• The method successfully detected biotinylated bovine serum albumin (bBSA) using streptavidin-coated magnetic beads.
• Detection limits of 1.5 pM for bBSA were achieved with the developed micro-chip sheathless flow cytometric device.
• The system demonstrated high sensitivity attributed to forward scattering for distinguishing aggregates from monomers.

Conclusions:

• The developed micro-chip sheathless flow cytometric device enables a simplified homogeneous bead-agglutination assay.
• This approach offers a promising, sensitive, and versatile method for immunoassays on microfluidic platforms.
• The system's simplicity and sensitivity support potential point-of-care diagnostic applications.