Abstract

In this paper, we present novel type of Surface-enhanced Raman spectroscopy (SERS) platform, based on stainless steel wire mesh (SSWM) covered with thin silver layer. The stainless steel wire mesh, typically used in chemical engineering industry, is a cheap and versatile substrate for SERS platforms. SSWM consists of multiple steel wires with diameter of tens of micrometers, which gives periodical structure and high stiffness. Moreover, stainless steel provides great resistance towards organic and inorganic solvents and provides excellent heat dissipation. It is worth mentioning that continuous irradiation of the laser beam over the SERS substrate can be a source of significant increase in the local temperature of metallic nanostructures, which can lead to thermal degradation or fragmentation of the adsorbed analyte. Decomposition or fragmentation of the analysed sample usually causea a significant decrease in the intensity of recorded SERS bands, which either leads to false SERS responses or enables the analysis of spectral data. To our knowledge, we have developed for the first time the thermally resistant SERS platform. This type of SERS substrate, termed Ag/SSWM, exhibit high sensitivity (Enhancement Factor (EF) = 106) and reproducibility (Relative Standard Deviation (RSD) of 6.4%) towards detection of p-mercaptobenzoic acid (p-MBA). Besides, Ag/SSWM allows the specific detection and differentiation between Gram-positive and Gram-negative bacterial species: Escherichia coli and Bacillus subtilis in label-free and reproducible manner. The unique properties of designed substrate overcome the limitations associated with photo- and thermal degradation of sensitive bacterial samples. Thus, a distinctive SERS analysis of all kinds of chemical and biological samples at high sensitivity and selectivity can be performed on the developed SERS-active substrate.

Highlights

  • Surface-enhanced Raman spectroscopy (SERS) is nowadays one of the most powerful and reliable method in a wide range of applications including biochemistry [1], biomedical analysis [2], forensics, bio- and chemical hazards [3] and environmental monitoring [4,5].In SERS effect, for molecules adsorbed onto metallic nanostructures, the Raman signal is amplified up to 14 orders of magnitude

  • It was found that the morphology and dielectric environment of the plasmonic nanostructures plays a crucial role in the EM mechanism

  • In recent research works we have investigated the membrane-based SERS-platforms [26,29], where polymer mats covered with gold nanostructures enable filtration of bacteria from fluids, their immobilization on the filter surface, and enhancement of Raman signal

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Summary

Introduction

Surface-enhanced Raman spectroscopy (SERS) is nowadays one of the most powerful and reliable method in a wide range of applications including biochemistry [1], biomedical analysis [2], forensics, bio- and chemical hazards [3] and environmental monitoring [4,5]. In recent research works we have investigated the membrane-based SERS-platforms [26,29], where polymer mats covered with gold nanostructures enable filtration of bacteria from fluids (for example, blood plasm), their immobilization on the filter surface, and enhancement of Raman signal. The developed SERS platforms, named Ag/SSWM, show very high surface-enhancement factor (1 × 106), high stability (up to one month under ambient conditions), high reproducibility, and high thermal resistance to laser irradiation These Ag/SSWM substrates demonstrated a great potential in sensitive and reproducible SERS-based detection of typical analyte like p-MBA, as well as whole microorganisms, that is, Escherichia coli and Bacillus subtilis

Chemicals and Materials
Raman and SERS Spectroscopy
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Procedure of Silver Sputtering
Characterization of Wire Mesh and Its Surface
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