Development of Gold Nanoparticle-Based SERS Substrates on TiO2-Coating to Reduce the Coffee Ring Effect.

René Breuch,Eleni Siefke,Cassandra Moers,Peter Kaul,Daniel Klein,Claudia Wickleder

doi:10.3390/nano12050860

René Breuch, Eleni Siefke + Show 4 more

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https://doi.org/10.3390/nano12050860

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Journal: Nanomaterials	Publication Date: Mar 3, 2022
Citations: 4	License type: CC BY 4.0

Affiliation: Hochschule Bonn-Rhein-Sieg, University of Siegen

Abstract

Hydrophilic surface-enhanced Raman spectroscopy (SERS) substrates were prepared by a combination of TiO2-coatings of aluminium plates through a direct titanium tetraisopropoxide (TTIP) coating and drop coated by synthesised gold nanoparticles (AuNPs). Differences between the wettability of the untreated substrates, the slowly dried Ti(OH)4 substrates and calcinated as well as plasma treated TiO2 substrates were analysed by water contact angle (WCA) measurements. The hydrophilic behaviour of the developed substrates helped to improve the distribution of the AuNPs, which reflects in overall higher lateral SERS enhancement. Surface enhancement of the substrates was tested with target molecule rhodamine 6G (R6G) and a fibre-coupled 638 nm Raman spectrometer. Additionally, the morphology of the substrates was characterised using scanning electron microscopy (SEM) and Raman microscopy. The studies showed a reduced influence of the coffee ring effect on the particle distribution, resulting in a more broadly distributed edge region, which increased the spatial reproducibility of the measured SERS signal in the surface-enhanced Raman mapping measurements on mm scale.

Highlights

Surface-enhanced Raman spectroscopy (SERS) is a special variant of Raman spectroscopy that is based on the enhancement of Raman scattered light, which can provide detailed information about molecular structures of a high variety of samples [1,2]
Aluminium plates were treated with a specific surface treatment and directly coated with TTIP
A nanostructured TiO2 surface was made visible by scanning electron microscopy (SEM) measurements and the hydrophilic character was confirmed by water contact angle measurements

Summary

Introduction

Surface-enhanced Raman spectroscopy (SERS) is a special variant of Raman spectroscopy that is based on the enhancement of Raman scattered light, which can provide detailed information about molecular structures of a high variety of samples [1,2]. Thereby CE originates from a charge transfer between a nanostructure like spherical nanoparticle and an adsorbing molecule. The charge transfer leads to an altered electronic structure of the molecule or the metal-adsorbate complex, which can lead to a higher Raman excitation probability. The. EE, on the other hand, is caused by the formation of a locally enhanced electromagnetic field at for example plasmonic-metallic nanostructures. EE, on the other hand, is caused by the formation of a locally enhanced electromagnetic field at for example plasmonic-metallic nanostructures If such structures are present in near-surface regions, the electromagnetic field from the plasmons that develops by light interaction, leads to an amplification of both the incident excitation light and of the emitted Raman scattered light [3,4]. Several methods for the fabrication of SERS-substrates found their way on to the commercial market and can be bought and used in different analyses [5–8]

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