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Wash-Free, Digital Immunoassay in Polydisperse Droplets
Samantha A Byrnes1, Toan Huynh1, Tim C Chang1
1Center for In Vitro Diagnostics, Intellectual Ventures Laboratory, Bellevue, Washington 98007, United States.
Analytical Chemistry
|January 31, 2020
Summary
We developed a simplified digital immunoassay using polydisperse droplets, eliminating wash steps for sensitive protein detection. This cost-effective method enhances usability for laboratory and point-of-care applications, improving disease diagnostics.
Area of Science:
- Biochemistry
- Biotechnology
- Analytical Chemistry
Background:
- Immunoassays are crucial for disease detection but often lack sensitivity.
- Existing digital assays require precise volumes and specialized equipment, limiting accessibility.
- Current methods can be expensive, cumbersome, and confined to centralized labs.
Purpose of the Study:
- To develop a simplified, sensitive, and accessible digital immunoassay.
- To overcome the limitations of traditional and current digital immunoassays.
- To enable sensitive protein quantification without specialized equipment or wash steps.
Main Methods:
- Developed a polydisperse digital droplet immunoassay (ddIA) using proximity ligation.
- Eliminated the need for wash steps, simplifying the assay to a single reagent addition.
- Utilized polydisperse droplets prepared without specialized equipment, a heater, and a fluorescent microscope.
Main Results:
- Achieved low limits of detection for interleukin-8 (IL-8): 0.793 pM in buffer and 1.54 pM in diluted whole blood.
- Demonstrated a one-pot, washless assay with improved usability compared to traditional methods.
- Developed a stochastic model for assay optimization and standard-curve-free quantification.
Conclusions:
- The polydisperse ddIA offers a sensitive, lower-cost, and simpler alternative for immunoassays.
- This assay is suitable for both centralized laboratory and point-of-care applications.
- The simplified approach enhances accessibility and broadens the application of digital immunoassays.
