Roughened silver electrodes for use in metal-enhanced fluorescence

Area of Science:

• Analytical Chemistry
• Materials Science
• Spectroscopy

Background:

• Roughened silver electrodes are established for Surface-Enhanced Raman Scattering (SERS).
• Metal-enhanced fluorescence (MEF) offers potential for sensitive detection methods.
• The application of roughened electrodes for MEF remains largely unexplored.

Purpose of the Study:

• To investigate the efficacy of in situ generated roughened silver electrodes for metal-enhanced fluorescence.
• To quantify the fluorescence enhancement of a model system using these electrodes.
• To explore the underlying mechanisms contributing to fluorescence enhancement.

Main Methods:

• Fabrication of roughened silver electrodes via constant current electrolysis in pure water, forming fractal-like structures on the cathode.
• Coating the electrodes with a monolayer of indocyanine green (ICG)-labeled human serum albumin (HSA).
• Measurement of fluorescence intensity and fluorescence lifetime of ICG-HSA on roughened and unroughened electrodes.

Main Results:

• Fractal-like structures were observed exclusively on the cathode.
• A significant ~50-fold increase in fluorescence intensity was achieved on the roughened cathode compared to the unroughened electrode.
• A two-fold increase in fluorescence was observed on the silver anode, which lacked fractal structures.
• Lifetime measurements indicated an increased radiative decay rate of ICG as a contributing factor to the enhanced fluorescence.

Conclusions:

• In situ generated roughened silver electrodes are effective for metal-enhanced fluorescence.
• This technique offers a promising new tool for fluorescence-based analytical assays, analogous to SERS applications.
• This represents the first report of utilizing roughened silver electrodes for metal-enhanced fluorescence.