Fluorescence enhancement and multiple protein detection in ZnO nanostructure microfluidic devices

Area of Science:

• Materials Science
• Nanotechnology
• Biomedical Engineering

Background:

• Microfluidic devices enable precise control over small fluid volumes, crucial for sensitive biomolecule detection.
• Zinc oxide (ZnO) nanostructures offer unique optical and electrical properties suitable for biosensing applications.
• Surface modification is essential for immobilizing biomolecules and ensuring specific binding events.

Purpose of the Study:

• To investigate and compare the biomolecule binding properties of different ZnO nanostructures (nanowires, rods, hexahedral-puncheon) grown in microfluidic channels.
• To evaluate the sensitivity and dynamic range of sharp ZnO nanowires for detecting streptavidin and specific proteins (IgG).
• To demonstrate the capability of sharp ZnO nanowires for multiplexed protein detection in a microfluidic array.

Main Methods:

• Growth of various ZnO nanostructures on glass substrates within microfluidic channels.
• Surface functionalization of ZnO nanostructures using 3-aminopropyl-triethoxysilane (3-APTES) and NHS-biotin.
• Infusion of dye-conjugated streptavidin and anti-IgG antibodies at varying concentrations through orthogonal microfluidic channels.
• Fluorescence intensity measurements at crossover areas to quantify biomolecule binding.
• Characterization of protein detection using sharp ZnO nanowires with varying concentrations of anti-mouse IgG.
• Demonstration of multiplexed detection using a microfluidic array for simultaneous detection of anti-mouse and anti-rabbit IgG.

Main Results:

• Sharp ZnO nanowires exhibited the largest dynamic range and highest fluorescent intensity compared to other ZnO morphologies.
• Simulated and experimental results for biomolecule binding showed good agreement.
• Sharp ZnO nanowires successfully detected protein concentrations ranging from 417 fM to 41.7 nM.
• Multiplexed detection of two different dye-conjugated antibodies (anti-mouse IgG and anti-rabbit IgG) was clearly demonstrated using sharp ZnO nanowires in a microfluidic array.

Conclusions:

• Sharp ZnO nanowires are highly effective for sensitive and specific biomolecule detection in microfluidic systems.
• The morphology of ZnO nanostructures significantly influences their performance in biosensing applications.
• The developed microfluidic platform with sharp ZnO nanowires holds promise for advanced diagnostics and high-throughput screening.