scholarly journals Developing a Novel Method of Analysis for Thiols in Sauvignon blanc

2021 ◽  
Author(s):  
◽  
Danica Christine Carter
Keyword(s):  
Electron Microscopy ◽  
New Zealand ◽  
Current Method ◽  
Gold Surface ◽  
Careful Analysis ◽  
Surface Enhanced Raman Spectroscopy ◽  
Market Potential ◽  
Sauvignon Blanc ◽  
Surface Enhanced Raman ◽  
Future Experimentation

<p>New Zealand wine had an export value of $1.21 billion in 2013. Of the total 170million litres of wine exported thatyear, Sauvignon blanc madeup 84.5%. Sauvignon blanc wines have specific flavours and aromas that consumers detect and enjoy including grapefruit, passion fruit,and citrus characters that are due to the presence of sulfur containing thiols. Unfortunately, thiols are also responsible for aromas such as cat’s urine, grass, and gasoline, which taint the flavour of a wine. Careful analysis of these compounds could lead to wines tailored to specific palates and a reduction of taint aromas and flavours, therefore further increasing the market potential for New Zealand Sauvignon blanc. The aim of this project was to further develop an SPME-based technique for thiol analysis of wine that is more reproducible, more accessible, and less toxic than the current method that concentrates the thiols using organomercury columns. To do this, gold nanoparticles were synthesised and coated onto SPME fibres in an attempt to selectively extract thiols from wine samples. Initial results showed an inconsistency between analyses and led to the need for a more comprehensive analysis ofthe gold surface,the gold-sulfur bond, and its RED-OX chemistry. Techniques employed for analysis of the gold surface included scanning electron microscopy, transmission electron microscopy,zeta-sizing and UV-VisSpectrophotometry. To examine the interactions between gold and sulfur, Surface-Enhanced Raman Spectroscopy and computational chemistry were used. The RED-OX chemistry was initially assessed in terms of the carrier gas in the gas chromatographs but was later changed to reductive and oxidative dips. It was found that an H2O2 dip in between samples oxidised the bound thiolates to a series of dimers that were easier to remove from the gold. While not yet completely resolving the hysteresis observed in previous attempts, this method of cleaning the fibres will lead to future experimentation and development in this area.</p>

scholarly journals Developing a Novel Method of Analysis for Thiols in Sauvignon blanc

2021 ◽  
Author(s):  
◽  
Danica Christine Carter
Keyword(s):  
Electron Microscopy ◽  
New Zealand ◽  
Current Method ◽  
Gold Surface ◽  
Careful Analysis ◽  
Surface Enhanced Raman Spectroscopy ◽  
Market Potential ◽  
Sauvignon Blanc ◽  
Surface Enhanced Raman ◽  
Future Experimentation

<p>New Zealand wine had an export value of $1.21 billion in 2013. Of the total 170million litres of wine exported thatyear, Sauvignon blanc madeup 84.5%. Sauvignon blanc wines have specific flavours and aromas that consumers detect and enjoy including grapefruit, passion fruit,and citrus characters that are due to the presence of sulfur containing thiols. Unfortunately, thiols are also responsible for aromas such as cat’s urine, grass, and gasoline, which taint the flavour of a wine. Careful analysis of these compounds could lead to wines tailored to specific palates and a reduction of taint aromas and flavours, therefore further increasing the market potential for New Zealand Sauvignon blanc. The aim of this project was to further develop an SPME-based technique for thiol analysis of wine that is more reproducible, more accessible, and less toxic than the current method that concentrates the thiols using organomercury columns. To do this, gold nanoparticles were synthesised and coated onto SPME fibres in an attempt to selectively extract thiols from wine samples. Initial results showed an inconsistency between analyses and led to the need for a more comprehensive analysis ofthe gold surface,the gold-sulfur bond, and its RED-OX chemistry. Techniques employed for analysis of the gold surface included scanning electron microscopy, transmission electron microscopy,zeta-sizing and UV-VisSpectrophotometry. To examine the interactions between gold and sulfur, Surface-Enhanced Raman Spectroscopy and computational chemistry were used. The RED-OX chemistry was initially assessed in terms of the carrier gas in the gas chromatographs but was later changed to reductive and oxidative dips. It was found that an H2O2 dip in between samples oxidised the bound thiolates to a series of dimers that were easier to remove from the gold. While not yet completely resolving the hysteresis observed in previous attempts, this method of cleaning the fibres will lead to future experimentation and development in this area.</p>

Plasmon Scanned Surface-Enhanced Raman Scattering Excitation Profiles

2002 ◽  
Vol 728 ◽  
Author(s):  
Christy L. Haynes ◽  
Richard P. Van Duyne
Keyword(s):  
Current Method ◽  
Surface Enhanced Raman Spectroscopy ◽  
Localized Surface Plasmon ◽  
The Novel ◽  
Enhancement Mechanism ◽  
Size Dependent ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Enhanced Raman Scattering ◽  
Nanostructured Metal

AbstractSince the discovery of surface-enhanced Raman spectroscopy (SERS) in 1977, scientists have come to understand the enhancement mechanism, but have been unable to consistently optimize the weak signals inherent in Raman experiments. Surface-enhanced Raman signals originate from excitation of the localized surface plasmon resonance (LSPR) of a nanostructured metal surface, thus producing concentrated electromagnetic fields at the surface of the nanostructure. Design of the nanostructured metal substrate plays an important role in understanding and optimizing SERS experiments. In this research, the size-dependent optical properties accessible by nanosphere lithography (NSL) are exploited to fabricate topographically predictable SERS-active substrates with systematically varying LSPRs. Correlated microextinction and micro-Raman measurements, as well as quantitative implementation of a Raman standard, allow significant improvements over the current method used to optimize SERS experiments. The knowledge gained in the novel plasmon scanned SERS excitation profiles clearly indicates the substrate parameters necessary for experimental optimization and promotes further understanding of the SERS enhancement mechanism.

Scanning Electron Microscopy and Surface Enhanced Raman Spectroscopy Correlation Studies of Functionalized Composite Organic-Inorganic SERS Nanoparticles on Cancer Cells

2011 ◽  
Vol 1316 ◽  
Author(s):  
Ai Leen Koh ◽  
Robert Sinclair
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Raman Spectroscopy ◽  
Cancer Cells ◽  
Surface Enhanced Raman Spectroscopy ◽  
Excitation Light ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Sers Intensity ◽  
Scanning Electron

ABSTRACTComposite Organic-Inorganic Nanoparticles (COINs) are a novel type of surface-enhanced Raman (SER) scattering nanoparticle formed by aggregating inorganic silver particles in the presence of a chosen organic molecule with a distinct Raman fingerprint. Binding between antibody-functionalized COINs and cells is detected primarily using Raman spectroscopy, which measures spectral shifts of the excitation light due to inelastic scattering. It has been suggested that the amount of antibody-conjugated COINs binding on cells will vary according to the antigen-expression levels in cells and will lead to changes in measured SERS intensities. COINs functionalized with antibodies CD54 and CD8 were conjugated to U937 and SupT1 cancer cells and investigated in this study. SERS intensity measurements were obtained from each of the four sample variants and normalized against control samples comprising non-antibody-functionalized COINs with cells. The amount of COINs binding on cells was determined using scanning electron microscopy (SEM) and correlated with the SER spectroscopy intensity. Although we found a positive correlation between the number of COINs binding to cells and their respective SERS intensity, this relationship is not one-to-one, nor does it appear to be linear. We demonstrated that SEM imaging and SER spectroscopy can complement each other to provide information about COINs binding onto cancer cells.

pH Dependence of the Size and Shape of the Gold Nanoparticles Prepared by Peptides

2013 ◽  
Vol 785-786 ◽  
pp. 484-487
Author(s):  
Chun Rong Wang
Keyword(s):  
Electron Microscopy ◽  
Gold Nanoparticles ◽  
Ph Dependence ◽  
Surface Enhanced Raman Spectroscopy ◽  
Gold Nanostructures ◽  
Size And Shape ◽  
Transmission Electron ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Potential Applications

The size and shape of gold nanoparticles controlled by pH was studied in the reacted solutions containing peptides (NH2-Leu-Aib-Trp-Ome) as reducing agent. The resulting gold nanostructures were characterized by transmission electron microscopy (TEM), XRD and UV-vis-NIR spectra. Different shape of gold nanoparticles such as spheres, multipod and branch were prepared by changing the pH of solution. The resulting gold nanostructures may be have potential applications in the Surface Enhanced Raman Spectroscopy (SERS) and NIR-absorbing filters and coatings.

scholarly journals Towards multiple readout application of plasmonic arrays

2011 ◽  
Vol 2 ◽  
pp. 501-508 ◽  
Author(s):  
Dana Cialla ◽  
Karina Weber ◽  
René Böhme ◽  
Uwe Hübner ◽  
Henrik Schneidewind ◽  
...  
Keyword(s):  
Strong Field ◽  
Field Enhancement ◽  
Gold Surface ◽  
Surface Enhanced Raman Spectroscopy ◽  
Metallic Surface ◽  
Simultaneous Application ◽  
Detection Scheme ◽  
Surface Enhanced Raman ◽  
Nanostructured Gold ◽  
Fluorescence Light

In order to combine the advantages of fluorescence and surface-enhanced Raman spectroscopy (SERS) on the same chip platform, a nanostructured gold surface with a unique design, allowing both the sensitive detection of fluorescence light together with the specific Raman fingerprint of the fluorescent molecules, was established. This task requires the fabrication of plasmonic arrays that permit the binding of molecules of interest at different distances from the metallic surface. The most efficient SERS enhancement is achieved for molecules directly adsorbed on the metallic surface due to the strong field enhancement, but where, however, the fluorescence is quenched most efficiently. Furthermore, the fluorescence can be enhanced efficiently by careful adjustment of the optical behavior of the plasmonic arrays. In this article, the simultaneous application of SERS and fluorescence, through the use of various gold nanostructured arrays, is demonstrated by the realization of a DNA detection scheme. The results shown open the way to more flexible use of plasmonic arrays in bioanalytics.

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