Highly sensitive fluorescence detection system for microfluidic lab-on-a-chip.

Area of Science:

• Biomedical Engineering
• Analytical Chemistry
• Optical Sensing

Background:

• Lab-on-a-chip (LOC) devices require sensitive and cost-effective detection systems.
• Existing fluorescence detection methods can be complex and expensive for widespread application.
• Accurate and rapid detection of cardiac markers is crucial for diagnosing myocardial infarction.

Purpose of the Study:

• To demonstrate a compact, low-cost, and practical fluorescence detection system for LOC applications.
• To validate the system's performance using fluorescence immunoassays for cardiac markers.
• To establish the limit of detection (LOD) for both optical measurements and human plasma samples.

Main Methods:

• Utilized a commercially available 501 nm InGaN light-emitting diode (LED) as the light source.
• Integrated organic or silicon photodiode detectors, dye-coated color filters, and polarizers.
• Employed an injection-molded polystyrene microfluidic chip for fluorescence immunoassays of myoglobin and CK-MB.

Main Results:

• Achieved an optical LOD of 5.6 × 10^4 beads/µl (∼3 nM fluorescein equivalent concentration).
• Determined a LOD of 1.5 ng/ml for both myoglobin and CK-MB in human plasma immunoassays.
• Demonstrated a practical and cost-effective fluorescence detection system suitable for LOC.

Conclusions:

• The developed fluorescence detection system is compact, affordable, and practical for LOC diagnostics.
• The system exhibits high sensitivity, capable of detecting cardiac markers at clinically relevant concentrations.
• This technology holds promise for point-of-care testing and rapid disease diagnosis.