A digital microfluidic approach to heterogeneous immunoassays.
Elizabeth M Miller1, Alphonsus H C Ng, Uvaraj Uddayasankar
1Department of Chemistry, University of Toronto, 80 St George St., Toronto, ON M5S 3H6, Canada.
Analytical and Bioanalytical Chemistry
|November 9, 2010
Summary
Digital microfluidics (DMF) enables faster, more efficient immunoassays by manipulating discrete droplets. This technology significantly reduces reagent use and analysis time for sandwich immunoassays.
Area of Science:
- Biotechnology
- Analytical Chemistry
- Microfluidics
Background:
- Immunoassays are crucial for detecting analytes but often require large reagent volumes and long analysis times.
- Conventional microfluidic devices use fluid streams, limiting flexibility and reconfigurability.
- Digital microfluidics (DMF) offers precise control over discrete droplets, enabling complex, multistep protocols.
Purpose of the Study:
- To develop and validate a heterogeneous sandwich immunoassay on a digital microfluidic (DMF) platform.
- To assess the performance of DMF in terms of reagent consumption, analysis time, sensitivity, and reproducibility.
- To demonstrate the potential of DMF for complex biological sample analysis.
Main Methods:
- A DMF device was utilized to perform a sandwich immunoassay for Human IgG detection.
- Anti-IgG antibodies were immobilized on the DMF surface for analyte capture.
- Discrete droplet manipulation via DMF actuation controlled all incubation and washing steps.
- Non-specific binding was minimized using Pluronic F-127 surfactant.
- Analyte detection was achieved using FITC-labeled anti-IgG and fluorescence measurement.
Main Results:
- Reagent and sample volumes were reduced by nearly three orders of magnitude compared to conventional methods.
- Total assay time was reduced to less than 2.5 hours.
- A dynamic range of approximately one order of magnitude was achieved with high reproducibility.
- Successful detection of Human IgG in complex matrices (bovine serum) with high specificity was demonstrated.
- Multiplexed DMF platforms increased assay throughput.
Conclusions:
- The digital microfluidic format is highly suitable for performing sandwich immunoassays.
- DMF offers significant advantages in reduced reagent usage and analysis time.
- This technology provides a flexible and efficient platform for qualitative and quantitative immunoassays.
- DMF has the potential to revolutionize diagnostic and analytical applications requiring immunoassays.
