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A low cost and high throughput magnetic bead-based immuno-agglutination assay in confined droplets
Bruno Teste1, Anaïs Ali-Cherif, Jean Louis Viovy
1Institut Curie, Centre de Recherche, Paris, France.
Insights
This study introduces a low-cost, high-throughput immunoassay using magnetic beads and microfluidic droplets. This method enables rapid and cost-effective analysis, offering advantages over traditional techniques.
Area of Science:
- Biotechnology
- Analytical Chemistry
- Microfluidics
Background:
- Traditional immunoassays often lack high throughput and require expensive equipment.
- Passive immuno-agglutination assays are simple but not suitable for large-scale analysis.
Purpose of the Study:
- To develop a low-cost, multimodal, and high-throughput immunoassay.
- To enhance agglutination kinetics and analyte quantitation using magnetic beads and microfluidics.
Main Methods:
- Utilized antibody-coated magnetic beads (MBs) in a homogeneous phase.
- Employed droplets microfluidics for sample containment and transport.
- Used magnetic tweezers to confine MBs, enhancing agglutination, and droplet recirculation for redispersion analysis.
Main Results:
- Achieved analyte quantitation based on MBs redispersion rate within droplets.
- Optimized parameters including magnetic field intensity, flow rate, and MB concentration.
- Demonstrated detection of biotinylated alkaline phosphatase at 100 pM with a throughput of 300 assays/hour.
Conclusions:
- The developed immunoassay offers advantages in reagent consumption and platform cost.
- Provides reproducible analyses with high throughput, surpassing existing technologies.
- Suitable for cost-effective and rapid diagnostic applications.
Abstract:
Although passive immuno-agglutination assays consist of one step and simple procedures, they are usually not adapted for high throughput analyses and they require expensive and bulky equipment for quantitation steps. Here we demonstrate a low cost, multimodal and high throughput immuno-agglutination assay that relies on a combination of magnetic beads (MBs), droplets microfluidics and magnetic tweezers. Antibody coated MBs were used as a capture support in the homogeneous phase. Following the immune interaction, water in oil droplets containing MBs and analytes were generated and transported in Teflon tubing. When passing in between magnetic tweezers, the MBs contained in the droplets were magnetically confined in order to enhance the agglutination rate and kinetics. When releasing the magnetic field, the internal recirculation flows in the droplet induce shear forces that favor MBs redispersion. In the presence of the analyte, the system preserves specific interactions and MBs stay in the aggregated state while in the case of a non-specific analyte, redispersion of particles occurs. The analyte quantitation procedure relies on the MBs redispersion rate within the droplet. The influence of different parameters such as magnetic field intensity, flow rate and MBs concentration on the agglutination performances have been investigated and optimized. Although the immuno-agglutination assay described in this work may not compete with enzyme linked immunosorbent assay (ELISA) in terms of sensitivity, it offers major advantages regarding the reagents consumption (analysis is performed in sub microliter droplet) and the platform cost that yields to very cheap analyses. Moreover the fully automated analysis procedure provides reproducible analyses with throughput well above those of existing technologies. We demonstrated the detection of biotinylated phosphatase alkaline in 100 nL sample volumes with an analysis rate of 300 assays per hour and a limit of detection of 100 pM.
