Grating-based surface plasmon resonance detection of core-shell nanoparticle mediated DNA hybridization

Area of Science:

• Nanotechnology
• Biophysics
• Analytical Chemistry

Background:

• Surface Plasmon Resonance (SPR) is a label-free optical sensing technique.
• DNA hybridization detection is crucial for diagnostics and molecular biology.
• Conventional SPR methods face limitations in sensitivity and signal enhancement.

Purpose of the Study:

• To investigate enhanced SPR detection of DNA hybridization.
• To utilize gold core-silica shell nanoparticles (CSNPs) in localized plasmonic fields.
• To improve the sensitivity and optical signatures of DNA detection.

Main Methods:

• Fabrication of periodic linear gratings with a 400 nm period.
• Immobilization of gold core-silica shell nanoparticles (CSNPs) on gratings.
• Experimental measurement of DNA hybridization using 24-mer single-stranded DNA oligomers.
• Comparison of CSNP-based SPR with conventional thin film SPR and gold nanoparticles.

Main Results:

• CSNPs on 400 nm gratings yielded a 36-fold enhancement in optical signatures compared to conventional SPR.
• CSNP-mediated DNA hybridization showed a 3-fold larger angular shift than gold nanoparticles of similar core size.
• Enhanced optical signatures are attributed to increased surface area, index contrast, and improved plasmon coupling.

Conclusions:

• The combined approach of CSNPs and grating structures significantly enhances SPR detection sensitivity.
• This method is expected to lower the limit of detection for biomolecular interactions to the fg/mm² range.
• The study demonstrates a promising platform for highly sensitive label-free biosensing.