Integrated self-calibration via electrokinetic solvent proportioning for microfluidic immunoassays

Area of Science:

• Biomedical Engineering
• Analytical Chemistry
• Microfluidics

Background:

• Immunoassays require accurate calibration standards for reliable quantification.
• Traditional off-chip standard preparation is time-consuming and prone to errors.
• Microfluidic devices offer potential for integrated and automated bioanalytical processes.

Purpose of the Study:

• To demonstrate on-board generation of calibration standards within a microfluidic device for immunoassay applications.
• To validate the use of electrokinetic flow for precise proportional mixing of reagents.
• To assess the accuracy and reproducibility of microfluidic-generated calibration standards.

Main Methods:

• Utilized a microfluidic device for on-chip generation of antibody (Ab) calibration standards.
• Employed electrokinetic flow for proportional mixing of Ab with a diluting buffer.
• Determined mixing ratios via electrical impedance modeling (P-SPICE) and analyzed fluorescently labeled bovine serum albumin (BSA*).

Main Results:

• Achieved linear calibration curves for fluorescently labeled amino acids (ratios 0.118-7.46) and immunoassays (ratios 0.197-5.077).
• Demonstrated peak height reproducibility of +/- 3% for immunoassay calibration.
• Reported 92 +/- 6% recovery for on-chip calibration compared to off-chip standards, indicating minimal bias.

Conclusions:

• On-board generation of calibration standards in microfluidic devices is feasible for immunoassays.
• Electrokinetic flow provides precise control over reagent mixing for standard preparation.
• The developed microfluidic system offers a reproducible and accurate alternative to traditional calibration methods.