Effect of Varying Electric Potential on Surface-Plasmon Resonance Sensing

Appl Opt. 2004 Jun 10;43(17):3426-32. doi: 10.1364/ao.43.003426.

Abstract

The high sensitivity of surface-plasmon resonance (SPR) sensors allows measurements of small variations in surface potentials to be made. We studied the changes of the SPR angle when an oscillating electric potential was applied to a gold film on which surface plasmons were excited. The shifts of the SPR resonance angle were observed for various aqueous solutions as an adjacent medium. A model that takes into account the redistribution of charges at the double layer near the metal-liquid interface as well as the oxidation of the gold film was developed. It was found that a change in the electronic density at voltages below the oxidation potential and, in addition, the oxidation of the gold surface above this potential are the main mechanisms that account for the observed dependences. It was shown that relatively slow oxidation-reduction processes can explain the observed hysteresis effect. Application of these techniques to studies of dielectric properties and conformational changes of polar biomolecules, such as tubulin, are discussed.

Publication types

  • Comparative Study
  • Evaluation Study
  • Research Support, Non-U.S. Gov't
  • Validation Study

MeSH terms

  • Electrochemistry / methods*
  • Electromagnetic Fields*
  • Gold / chemistry*
  • Models, Chemical*
  • Oxidation-Reduction
  • Solutions
  • Surface Plasmon Resonance / methods*
  • Water / analysis
  • Water / chemistry*

Substances

  • Solutions
  • Water
  • Gold