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A digital microfluidic approach to increasing sample volume and reducing bead numbers in single molecule array
Alinaghi Salari1,2, Jose Gilberto Camacho Valenzuela2,3, Nguyen Le1,2
1Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, ON M5S 3H6, Canada. aaron.wheeler@utoronto.ca.
Lab on a Chip
|February 24, 2025
Summary
Digital microfluidics (DMF) enhances single molecule array (Simoa) digital protein assays by improving magnetic bead manipulation. This breakthrough enables more sensitive protein detection in miniaturized systems, overcoming previous volume and bead count limitations.
Area of Science:
- Biotechnology
- Analytical Chemistry
- Microfluidics
Background:
- Digital protein detection using Single Molecule Array (Simoa) has vast clinical potential.
- Miniaturized Simoa systems are hindered by large sample volumes and low bead counts.
- Digital microfluidics (DMF) offers a platform for miniaturization but requires improved bead handling.
Purpose of the Study:
- To enhance magnetic bead manipulation within digital microfluidics (DMF) for improved Simoa assay performance.
- To overcome limitations of sample volume and bead numbers in miniaturized Simoa systems.
- To develop novel strategies for integrating DMF with Simoa-based digital protein assays.
Main Methods:
- Developed strategies for loading sample-bead mixtures into DMF networks using virtual channels or small liquid segments.
- Implemented parallel or stepwise liquid handling methods.
- Utilized a dedicated densifying electrode technique for efficient capture of low bead numbers and minimal liquid residuals.
Main Results:
- Achieved improved integration of DMF with Simoa assays.
- Demonstrated high bead retention with minimal residual liquid using the densifying electrode technique.
- Optimized front-end assay processing for beads using DMF.
- Successfully detected tumor necrosis factor α (TNF-α) using Simoa with DMF, achieving performance equivalent to microtitre plate assays.
Conclusions:
- The developed DMF methods significantly improve magnetic bead manipulation for Simoa assays.
- These advancements enable more sensitive digital protein detection in miniaturized analytical systems.
- The strategies pave the way for broader integration of DMF and Simoa in diverse applications.
