Fluorescence enhancements on silver colloid coated surfaces.

Area of Science:

• Biophysics
• Materials Science
• Nanotechnology

Background:

• Metal-enhanced fluorescence (MEF) utilizes plasmonic properties of noble metals to amplify light emission from nearby fluorophores.
• Silver nanostructures are known to exhibit strong plasmonic effects, making them promising for MEF applications.

Purpose of the Study:

• To investigate the potential of silver colloid coated surfaces (SCCS) and silver island films (SIFs) as substrates for metal-enhanced fluorescence.
• To quantify the fluorescence enhancement of Texas Red-labeled bovine serum albumin (BSA) and fluorescein-labeled human serum albumin (HSA) on these silvered surfaces.
• To explore the impact of silver nanoparticles on the photophysical properties, such as fluorescence lifetime and self-quenching, of the labeled proteins.

Main Methods:

• Deposition of Texas Red-labeled BSA and fluorescein-labeled HSA on SCCS and SIFs.
• Measurement of fluorescence emission intensity and fluorescence lifetimes using spectrofluorometry.
• Comparison of fluorescence properties on silvered surfaces versus uncoated quartz substrates.

Main Results:

• A >16-fold fluorescence enhancement of Texas Red-BSA on SCCS and an ~8-fold enhancement on SIFs.
• Significantly shorter fluorescence lifetimes for Texas Red-BSA on silvered surfaces, indicating altered radiative decay rates.
• A 36-fold increased brightness for overlabeled fluorescein-HSA on SCCS, with evidence suggesting reduced self-quenching by silver particles.

Conclusions:

• Silver colloid coated surfaces are highly effective substrates for achieving significant metal-enhanced fluorescence.
• The observed changes in fluorescence lifetime and reduced self-quenching highlight the utility of SCCS for improving the sensitivity of fluorescently labeled biomolecules.
• These findings establish SCCS as valuable platforms for advanced bio-imaging and sensing technologies leveraging MEF.