Electrochemical Surface Plasmon Resonance Spectroscopy at Bilayered Silver/Gold Films

Abstract

Bilayered silver/gold films (gold deposited on top of the silver film) were used as substrates for electrochemical surface plasmon resonance spectroscopy (EC-SPR). EC-SPR responses of electrochemical deposition/stripping of copper and redox-induced conformation changes of cytochrome c immobilized onto self-assembled monolayers preformed at these substrates were measured. Influence of the Ag layer thickness and the double-layer capacitance on the EC-SPR behavior was investigated. The results demonstrated that the bilayered Ag/Au metal films produce a sharper SPR dip profile than pure Au films and retain the high chemical stability of Au films. Contrary to the result by the Fresnel calculation that predicts a greater fraction of Ag in the bilayered film should result in a greater signal-to-noise ratio, the EC-SPR sensitivity is dependent on both the Ag/Au thickness ratio and the chemical modification of the surface. Factors affecting the overall SPR sensitivity at the bilayered films, such as the film morphology, potential-induced excess surface charges, and the adsorbate layer were investigated. Forming a compact adsorbate layer at the bilayered film diminishes the effect of potential-induce excess surface charges on the SPR signal and improves the overall EC-SPR sensitivity. For the case of redox-induced conformation changes of cytochrome c, the SPR signal obtained at the bilayered silver/gold film is 2.7 times as high as that at a pure gold film.

Studies into the interaction of a ferrocene-conjugates of Gly-Gly-Arg-Tyr with papain: AC voltammetry, impedance spectroscopy and surface plasmon resonance studies

“…The greater the mass adsorbed, the greater the shift. The position of SPR angle and resonance curve shape are very sensitive to changes in the index of refraction at the solid surface, which in turn is influenced by changes in the thickness [16] and are consistent with AC voltammetry and impedance results. Fig.…”

Surface Plasmon Resonance Coupled with Potential‐step Chronoamperometry: Theory and Applications for Quantitative Measurements of Electrodeposited Thin Films

“…Numerical Simulation . The Fresnel calculation of the film thickness was performed with the Winspall software version 3.02 . In the calculation, a hemispherical prism was used.…”

“…Thus far, coupling EC to SPR is not without its own problems. Specifically, when cyclic voltammetry (CV) is used in conjunction with SPR, the potential scan can affect one or more of the three terms that contribute to the overall SPR angle change, Δ θ : …”

Sensitive and Label-Free Detection of DNA by Surface Plasmon Resonance

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