Backscattering particle immunoassays in wire-guide droplet manipulations

Area of Science:

• Biotechnology
• Microfluidics
• Assay Development

Background:

• Conventional open-surface digital microfluidics methods present significant complexities.
• Existing microfluidic and microwell plate assays have limitations in sensitivity and reusability.

Purpose of the Study:

• To demonstrate a simplified approach for digital microfluidics droplet manipulation.
• To develop a more sensitive and reusable platform for immunoassays.

Main Methods:

• Utilized stepper motors and microcontrollers for programmed manipulation of 10 µL droplets.
• Employed a superhydrophobic surface (contact angle = 155 ± 2°) for droplet merging and movement.
• Implemented back-light scattering detection for latex immunoagglutination assays.

Main Results:

• Achieved programmed droplet movements including merging, complex path following, and rapid mixing.
• Demonstrated highly sensitive detection limits for mouse immunoglobulin G (50 pg mL⁻¹), bovine viral diarrhea virus (2.5 TCID₅₀ mL⁻¹), and Escherichia coli (85 CFU mL⁻¹).
• Exhibited significantly lower detection limits compared to conventional microfluidic assays.

Conclusions:

• The developed system offers a simpler, more efficient alternative to existing digital microfluidics techniques.
• The platform demonstrates minimal biofouling, allows for over 100 uses, and enables nanoliter droplet manipulation.
• The system is reprogrammable, enhancing its versatility for various applications.