Gold nanoparticle thin films fabricated by electrophoretic deposition method for highly sensitive SERS application

Sheng-Qing Zhu,Xin-Li Guo,Tong Zhang,Xiao-Yang Zhang,Qi-Long Wang,Xuefeng Liu

doi:10.1186/1556-276x-7-613

Abstract

We report an electrophoretic deposition method for the fabrication of gold nanoparticle (GNP) thin films as sensitive surface-enhanced Raman scattering (SERS) substrates. In this method, GNP sol, synthesized by a seed-mediated growth approach, and indium tin oxide (ITO) glass substrates were utilized as an electrophoretic solution and electrodes, respectively. From the scanning electron microscopy analysis, we found that the density of GNPs deposited on ITO glass substrates increases with prolonged electrophoresis time. The films possess high mechanical adhesion strength and exhibit strong localized surface plasmon resonance (LSPR) effect by showing high SERS sensitivity to detect 1 × 10−7 M rhodamine 6 G in methanol solution. Finally, the relationship between Raman signal amplification capability and GNP deposition density has been further investigated. The results of our experiment indicate that the high-density GNP film shows relatively higher signal amplification capability due to the strong LSPR effect in narrow gap regions between the neighboring particles on the film.

Highlights

Films composed of noble metal nanoparticles currently have attained wide popularity and aroused intense research interest in nanotechnology due to the intriguing optical properties introduced by localized surface plasmon resonances (LSPRs)
LSPRs, which are optical phenomenona arising from the collective oscillation of conduction electrons in noble metal nanoparticles when the electrons are disturbed from their equilibrium positions, lead to enormous optical local-field enhancement at the nanoscale and obtain potential applications in many fields such as chemical or biosensors [1,2,3,4], solar cell designs [5,6,7,8], and surface-enhanced Raman scattering (SERS) [9,10,11]
It is found that the gold nanoparticle (GNP) are single crystals with a nearly uniform spherical shape and well dispersed in the solution due to the Coulomb repulsion effect, which was introduced by the bilayers of CTAB on GNPs' surfaces [22]

Summary

Introduction

Films composed of noble metal nanoparticles (typically, Au or Ag) currently have attained wide popularity and aroused intense research interest in nanotechnology due to the intriguing optical properties introduced by localized surface plasmon resonances (LSPRs). Due to the exceptional optical properties of noble metal nanoparticle films, many available methods for the fabrication of these films have been proposed in the past two. We report a rapid, simple, and roomtemperature electrophoretic deposition method using gold nanoparticle (GNP) sol as an electrophoretic solution to fabricate sensitive GNP films with high mechanical adhesion strength. We demonstrate the excellent signal enhancement ability of these GNP thin films as substrates in SERS measurements and find that rhodamine 6 G (R6G) molecules can be detected at very low concentrations using these films

Methods

Results

Conclusion