Evaluation of direct versus multi-layer passivation and capture chemistries for nanoparticle-based biosensor...

Area of Science:

• Nanotechnology
• Biomedical Engineering
• Analytical Chemistry

Background:

• Biosensors using nanoparticles often fail in complex biological fluids due to surface fouling and non-specific binding.
• This interference from proteins, lipids, nucleic acids, and saccharides hinders accurate detection.

Purpose of the Study:

• To systematically investigate four orthogonal nanoparticle surface functionalization methods.
• To evaluate their performance in buffer and serum for biosensor applications.

Main Methods:

• Carbodiimide coupling, copper-mediated 'click' coupling, copper-free click coupling, and thiol-maleimide coupling were quantitatively controlled.
• A sandwich immunoassay using analyte-mediated aggregation of fluorescent reporters and paramagnetic nanoparticles was employed.
• Performance was probed using dengue fever biomarker NS-1.

Main Results:

• Surface functionalization critically impacts assay performance in buffer versus serum.
• Copper-free click coupling demonstrated a 10-fold increase in the dynamic range for NS1 detection compared to carbodiimide coupling.
• Controlled nanoparticle sizing and functionalization reduced fluorescence background by over 10-fold and improved sensitivity by nearly two orders of magnitude.

Conclusions:

• Optimized nanoparticle surface functionalization is vital for robust biosensor performance in complex biological matrices.
• Copper-free click coupling offers superior performance for sensitive and specific biomarker detection.