Application of gold nanoparticles–epoxy surface nanocomposites for controlling hotspot density on a large surface area for SERS applications

Attila Bonyár,Shereen Zangana,Tomáš Lednický,István Rigó,István Csarnovics,Miklós Veres

doi:10.1016/j.nanoso.2021.100787

Abstract

The applicability of a novel gold–epoxysurface nanocomposite for surface-enhanced Raman scattering (SERS) is investigated. The nanocomposite consists of ellipsoidal nanoparticles in a hexagonal arrangement, where the average particle diameter (D0) and interparticle gap (D) can be controlled in the 0.15–1.00 (D/D0) range on a large surface area (several cm 2). Numerical simulations were used to estimate the SERS enhancement factors of substrates with five different particle arrangements. The fabricated substrates’ surface was functionalized with 20 base-pair long double-stranded DNA molecules and the intensities of the characteristic Raman peaks related to DNA were used to quantify the substrate performance. It was proved that by optimizing the fabrication parameters and maximizing the interparticle coupling, the characteristic Raman intensities could be increased by more than 2.5 orders of magnitude.

Highlights

One of the most promising application areas of plasmonic noble metal nanoparticles is surface-enhanced Raman scattering (SERS), an ultrasensitive vibrational spectroscopy method that provides specific fingerprint information of analytes [1]
The field intensity and the spectral position of the LSPR absorption peak are strongly dependent on the geometrical properties of the nanoparticle arrangements
This phase consists of polymer casting, aluminium template removal by chemical etching and the subsequent plasma etching of the polymer substrate to make the nanoparticles accessible

Summary

Introduction

One of the most promising application areas of plasmonic noble metal nanoparticles is surface-enhanced Raman scattering (SERS), an ultrasensitive vibrational spectroscopy method that provides specific fingerprint information of analytes [1]. According to the widely accepted electrochemical enhancement mechanism, SERS enhancement can reach multiple orders of magnitude in the intense plasmon near-field around the excited particles. The field intensity and the spectral position of the LSPR (localized surface plasmon resonance) absorption peak are strongly dependent on the geometrical properties of the nanoparticle arrangements (e.g., particle shape, size and interparticle distance). For different Raman excitation wavelengths, these respective parameters should be optimized in order to maximize the achievable SERS enhancement with the nanostructures, which is the main effort and focus of many recent works [1,2,3]. It was shown that the near-field intensities could be multiplied by utilizing coupling between the nanostructures and the resulting hotspots contribute significantly to the overall SERS enhancement. The fact that decreasing the interparticle gap leads to an increased Raman intensity has been proven both experimentally and by simulations [4,5,6]

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