Immunoassays based on surface-enhanced fluorescence using gap-plasmon-tunable Ag bilayer nanoparticle films

Area of Science:

• Nanotechnology
• Plasmonics
• Biomedical Engineering

Background:

• Traditional silver nanoparticle monolayer films have limitations in controlling plasmonic properties.
• Immunoassays require sensitive detection methods for accurate diagnostics.

Purpose of the Study:

• To demonstrate a novel, gap-plasmon-tunable silver bilayer nanoparticle film for enhanced immunoassays.
• To investigate the effect of polyelectrolyte interlayers on plasmonic properties and fluorescence enhancement.

Main Methods:

• Fabrication of silver bilayer nanoparticle films by sequential deposition of silver nanoparticles and polyelectrolyte layers.
• Tuning of gap plasmon resonance by controlling the number of polyelectrolyte interlayers.
• Experimental evaluation of fluorescence enhancement capabilities and application in fluorescence immunoassays.

Main Results:

• Gap plasmon resonance was tunable across the visible spectrum by adjusting polyelectrolyte interlayer thickness.
• A maximal fluorescence enhancement of approximately 15.4-fold was achieved with 7 polyelectrolyte layers.
• Application in fluorescence immunoassay yielded a 3.3-fold enhancement compared to glass substrates.

Conclusions:

• The developed silver bilayer nanoparticle films offer tunable plasmonic properties for significant fluorescence enhancement.
• These plasmonic substrates show great potential for improving the sensitivity of fluorescence-based immunoassays.
• The fabrication method provides new insights for designing advanced plasmonic substrates.