Optimization of a microfluidic electrophoretic immunoassay using a Peltier cooler

Area of Science:

• Analytical Chemistry
• Biochemistry
• Microfluidics

Background:

• Electrophoretic affinity assays require stable complexes for accurate analysis.
• Joule heating in microfluidic devices can dissociate complexes, reducing assay sensitivity.
• Glass microfluidics exacerbate heat dissipation issues, impacting assay performance.

Purpose of the Study:

• To develop a method for cooling glass microfluidic chips during affinity assays.
• To improve the preservation of affinity complexes and enhance assay sensitivity.
• To enable higher separation voltages and achieve lower detection limits for insulin.

Main Methods:

• Implemented a Peltier cooler to actively cool the separation channel of a glass microfluidic chip.
• Investigated the effect of temperature stabilization on complex preservation and assay performance.
• Utilized kinetic capillary electrophoresis (CE) to optimize separation voltage and temperature.
• Generated a calibration curve under optimal conditions to determine detection limits.

Main Results:

• Active cooling stabilized temperatures at 21°C, minimizing detrimental thermal gradients.
• Passive and active cooling significantly improved affinity complex preservation (2-fold increase).
• Thermostabilization allowed for higher separation voltages (6 kV), improving assay performance.
• Achieved 1 nM limits of detection for insulin, a 10-fold improvement over non-thermostated conditions.

Conclusions:

• Peltier cooling effectively addresses Joule heating limitations in glass microfluidic affinity assays.
• The developed methodology significantly enhances assay sensitivity and robustness.
• This cooling technique is broadly applicable to various microfluidic affinity assay applications.