Enhancing biosensing sensitivity of metal nanostructures through site-selective binding

Area of Science:

• Nanotechnology
• Biosensing
• Surface Chemistry

Background:

• Localised surface plasmon resonance (LSPR) generates intense electromagnetic fields at nanostructure surfaces.
• High sensitivity in LSPR biosensors relies on precise localization of target molecules at these intense field sites.

Purpose of the Study:

• To enhance LSPR biosensor sensitivity by controlling biomolecule adsorption sites.
• To investigate the effect of surface modification on the detection of alpha-fetoprotein (AFP).

Main Methods:

• Fabrication of gold nano-truncated cone (GNTC) arrays using thermal nanoimprint lithography.
• Surface modification by capping the top surface of GNTCs with oxides.
• Detection of AFP using sandwich immunoassay and enzymatic precipitation on capped and uncapped arrays.
• Characterization using atomic force microscopy (AFM) and electron microscopy (EM).

Main Results:

• Oxide capping effectively blocked biomolecule adsorption on the top surface of GNTCs.
• Target molecules preferentially adsorbed on the side surfaces of the GNTCs.
• The oxide-capped GNTC array demonstrated significantly higher detection sensitivity for AFP compared to the uncapped array.
• A six-fold enhancement in sensitivity was observed in serum samples.

Conclusions:

• Strategic surface modification of nanostructures is crucial for optimizing LSPR biosensor performance.
• Blocking non-optimal adsorption sites enhances target molecule localization and improves biosensor sensitivity.
• This approach offers a promising strategy for developing highly sensitive LSPR-based diagnostic tools.