Heterogeneous immunoassays in microfluidic format using fluorescence detection with integrated amorphous silicon...

Area of Science:

• Biomedical Engineering
• Analytical Chemistry
• Materials Science

Background:

• Microfluidic technology offers miniaturization for immunoassays, reducing time and reagent needs.
• Lab-on-chip systems integrate multiple functions for portable and efficient analysis.
• Direct fluorescence detection of molecular recognition is crucial for sensitive diagnostics.

Purpose of the Study:

• To develop and validate a microfluidic lab-on-chip system for direct, quantitative immunoassay detection.
• To integrate a novel amorphous silicon photodiode and fluorescence filter with a microfluidic network.
• To assess the system's performance for antibody-antigen recognition analysis.

Main Methods:

• Fabrication of a lab-on-chip device with amorphous silicon (a-Si:H) photodiode and a-Si:C alloy filter.
• Integration with a polydimethylsiloxane (PDMS)-based microfluidic network.
• Flow-through immunoassay using fluorescently labeled antibodies (quantum dots) for direct detection.

Main Results:

• Successful direct detection of antibody-antigen molecular recognition in a microfluidic format.
• Assay time reduced to 30 minutes with quantitative detection.
• Measurements from the a-Si:H photodiode correlated with fluorescence microscopy.
• Linear detection range observed from nanomolar to micromolar antibody concentrations.

Conclusions:

• The developed microfluidic lab-on-chip system enables rapid and quantitative immunoassays.
• The integrated a-Si:H photodiode and filter system is effective for direct fluorescence detection.
• This technology holds potential for portable, low-reagent diagnostic applications.