Flow-through microfluidic immunosensors with refractive index-matched silica monoliths as volumetric optical...

Area of Science:

• Biosensing
• Materials Science
• Analytical Chemistry

Background:

• Developing sensitive and rapid immunoassays is crucial for disease diagnostics and monitoring.
• Existing methods often face limitations in sensitivity, speed, or complexity.
• Porous materials offer advantages for high-density probe immobilization and efficient analyte capture.

Purpose of the Study:

• To demonstrate a novel absorbance-based immunosensor utilizing ex situ functionalized porous silica monoliths.
• To achieve sensitive and rapid detection of target antigens using a flow-through microfluidic system.
• To enhance optical detection through gold nanoparticle immunoconjugates and silver enhancement.

Main Methods:

• Synthesis and off-chip functionalization of porous silica monoliths with immunocapture probes.
• Integration of functionalized monoliths into a sealed thermoplastic microfluidic device.
• Application of gold nanoparticle immunoconjugates, silver enhancement, and index matching with sucrose solution.

Main Results:

• Achieved a detection limit as low as 1 ng/mL for a sandwich assay.
• Demonstrated a dynamic range of at least 4 orders of magnitude.
• Confirmed sensitive and rapid detection of target antigens with high capture probe density and short diffusion lengths.

Conclusions:

• The combination of functionalized porous silica monoliths and on-chip index matching enables practical flow-through immunoassays.
• This approach offers a sensitive and rapid method for detecting target antigens.
• The developed immunosensor shows potential for various diagnostic applications.