Lab-on-a-chip immunoassay for multiple antibodies using microsphere light scattering and quantum dot emission

Area of Science:

• Biotechnology
• Analytical Chemistry
• Materials Science

Background:

• Lab-on-a-chip (LOC) immunoassays are crucial for diagnostics.
• Current methods often require complex sample preparation and lack multiplexing capabilities.
• Quantum dots (QDs) offer bright fluorescence but can be challenging to handle.

Purpose of the Study:

• To develop a novel nano-on-micro (NOM) configuration for enhanced LOC immunoassay.
• To enable simultaneous detection of multiple analytes with improved limit of detection (LOD).
• To simplify assay procedures by eliminating the need for stationary supports.

Main Methods:

• Conjugating QDs emitting at different wavelengths onto distinct microspheres.
• Utilizing a "nano-on-micro" (NOM) strategy for enhanced light scattering and fluorescence.
• Performing on-chip detection in a microfluidic device using proximity optical fibers for simultaneous light scattering and fluorescence measurements.

Main Results:

• NOMs exhibited stronger light scattering than individual QDs or microspheres.
• A decrease in QD fluorescence signal indicated a positive antigen-antibody reaction.
• Achieved a low LOD of 50 ng/mL (330 pM) with simultaneous detection of two different antibodies (anti-mIgG and anti-BSA).

Conclusions:

• The NOM bioassay enables sensitive, multiplexed detection of antibodies in a single step.
• This approach simplifies sample processing and handling for lab-on-a-chip immunoassays.
• NOM technology holds promise for high-throughput screening and diagnostics.