Indirect Quantification of Glyphosate by SERS Using an Incubation Process With Hemin as the Reporter Molecule: A Contribution to Signal Amplification Mechanism

The indirect determination of the most used herbicide worldwide, glyphosate, was achieved by the SERS technique using hemin chloride as the reporter molecule. An incubation process between hemin and glyphosate solutions was required to obtain a reproducible Raman signal on SERS substrates consisting of silicon decorated with Ag nanoparticles (Si-AgNPs). At 780 nm of excitation wavelength, SERS spectra from hemin solutions do not show extra bands in the presence of glyphosate. However, the hemin bands increase in intensity as a function of glyphosate concentration. This allows the quantification of the herbicide using as marker band the signal associated with the ring breathing mode of pyridine at 745 cm−1. The linear range was from 1 × 10−10 to 1 × 10−5 M and the limit of detection (LOD) was 9.59 × 10−12 M. This methodology was successfully applied to the quantification of the herbicide in honey. From Raman experiments with and without silver nanoparticles, it was possible to state that the hemin is the species responsible for the absorption in the absence or the presence of the herbicide via vinyl groups. Likewise, when the glyphosate concentration increases, a subtle increase occurs in the planar orientation of the vinyl group at position 2 in the porphyrin ring of hemin over the silver surface, favoring the reduction of the molecule. The total Raman signal of the hemin-glyphosate incubated solutions includes a maximized electromagnetic contribution by the use of the appropriate laser excitation, and chemical contributions related to charge transfer between silver and hemin, and from resonance properties of Raman scattering of hemin. Incubation of the reporter molecule with the analyte before the conjugation with the SERS substrate has not been explored before and could be extrapolated to other reporter-analyte systems that depend on a binding equilibrium process.

Download Full-text

Off-Resonance Gold Nanobone Films at Liquid Interface for SERS Applications

Sensors ◽

10.3390/s22010236 ◽

2021 ◽

Vol 22 (1) ◽

pp. 236

Author(s):

Rebeca Moldovan ◽

Valentin Toma ◽

Bogdan-Cezar Iacob ◽

Rareș Ionuț Știufiuc ◽

Ede Bodoki

Keyword(s):

Limit Of Detection ◽

Fold Increase ◽

Colloidal Dispersion ◽

Surface Enhanced Raman Spectroscopy ◽

Liquid Interface ◽

Excitation Wavelength ◽

Raman Signal ◽

Plasmonic Nanostructures ◽

Trace Detection ◽

Relative Standard

Extensive effort and research are currently channeled towards the implementation of SERS (Surface Enhanced Raman Spectroscopy) as a standard analytical tool as it has undisputedly demonstrated a great potential for trace detection of various analytes. Novel and improved substrates are continuously reported in this regard. It is generally believed that plasmonic nanostructures with plasmon resonances close to the excitation wavelength (on-resonance) generate stronger SERS enhancements, but this finding is still under debate. In the current paper, we compared off-resonance gold nanobones (GNBs) with on-resonance GNBs and gold nanorods (GNRs) in both colloidal dispersion and as close-packed films self-assembled at liquid-liquid interface. Rhodamine 6G (R6G) was used as a Raman reporter in order to evaluate SERS performances. A 17-, 18-, and 55-fold increase in the Raman signal was observed for nanostructures (off-resonance GNBs, on-resonance GNBs, and on-resonance GNRs, respectively) assembled at liquid-liquid interface compared to the same nanostructures in colloidal dispersion. SERS performances of off-resonance GNBs were superior to on-resonance nanostructures in both cases. Furthermore, when off-resonance GNBs were assembled at the liquid interface, a relative standard deviation of 4.56% of the recorded signal intensity and a limit of detection (LOD) of 5 × 10−9 M could be obtained for R6G, rendering this substrate suitable for analytical applications.

Download Full-text

Liquid Surface-Enhanced Raman Spectroscopy (SERS) Sensor-Based Au-Ag Colloidal Nanoparticles for Easy and Rapid Detection of Deltamethrin Pesticide in Brewed Tea

Crystals ◽

10.3390/cryst12010024 ◽

2021 ◽

Vol 12 (1) ◽

pp. 24

Author(s):

Affi Nur Hidayah ◽

Djoko Triyono ◽

Yuliati Herbani ◽

Rosari Saleh

Keyword(s):

Raman Spectroscopy ◽

Liquid Surface ◽

Limit Of Detection ◽

Surface Enhanced Raman Spectroscopy ◽

Ease Of Use ◽

Raman Signal ◽

Colloidal Nanoparticles ◽

Sers Substrate ◽

Surface Enhanced ◽

Surface Enhanced Raman

Deltamethrin pesticides can cause inflammation, nephrotoxicity and hepatotoxicity as well as affect the activity of antioxidant enzymes in tissues. As a result of this concern, there is a rising focus on the development of fast and reliable pesticide residue testing to minimise potential risks to humans. The goal of this study is to use Au-Ag colloid nanoparticles as liquid surface-enhanced Raman spectroscopy (SERS) to improve the Raman signal in the detection of deltamethrin pesticide in a brewed tea. The liquid SERS system is fascinating to study due to its ease of use and its unlikeliness to cause several phenomena, such as photo-bleaching, combustion, sublimation and even photo-catalysis, which can interfere with the Raman signal, as shown in the SERS substrate. Our liquid SERS system is simpler than previous liquid SERS systems that have been reported. We performed the detection of pesticide analyte directly on brewed tea, without diluting it with ethanol or centrifuging it. Femtosecond laser-induced photo-reduction was employed to synthesise the liquid SERS of Au, Au-Ag, and Ag colloidal nanoparticles. The SERS was utilised to detect deltamethrin pesticide in brewed tea. The result showed that liquid SERS-based Ag NPs significantly enhance the Raman signal of pesticides compared with liquid SERS-based Au NPs and Au-Ag Nanoalloys. The maximum residue limits (MRLs) in tea in Indonesia are set at 10 ppm. Therefore, this method was also utilised to detect and improve, to 0.01 ppm, the deltamethrin pesticide Limit of Detection (LOD).

Download Full-text

Optimization and Characterization of Paper-based SERS Substrates for Detection of Melamine

Communications in Physics ◽

10.15625/0868-3166/30/0/14832 ◽

2020 ◽

Vol 30 (4) ◽

pp. 345

Author(s):

Bich Ngoc Nguyen Thi ◽

Viet Ha Chu ◽

Thi Thuy Nguyen ◽

Trong Nghia Nguyen ◽

Hong Nhung Tran

Keyword(s):

Limit Of Detection ◽

Chemical Reduction ◽

Low Cost ◽

Sers Substrate ◽

Sers Substrates ◽

Surface Enhanced Raman ◽

Enhanced Raman Scattering ◽

Silver Nitrate Concentration ◽

Filter Papers

A flexible low-cost paper-based surface enhanced Raman scattering (SERS) substrate was successfully manufactured by a direct chemical reduction of silver nanoparticles (AgNPs) onto a common commercially available filter paper. Characterization of fabricated paper-based SERS substrate and the influences of the silver nitrate concentration, type of paper on SERS signal were systematically investigated. In order to fabricate SERS substrates with the highest quality, a suitable one from four different types of filter papers was chosen. The prepared SERS substrates have capability for detecting food toxic chemicals. The test of detecting melamine in aqueous solution was successfully demonstrated with the limit of detection for melamine is 10-7M.

Download Full-text

Genetic Algorithm-Driven Surface-Enhanced Raman Spectroscopy Substrate Optimization

Nanomaterials ◽

10.3390/nano11112905 ◽

2021 ◽

Vol 11 (11) ◽

pp. 2905

Author(s):

Buse Bilgin ◽

Cenk Yanik ◽

Hulya Torun ◽

Mehmet Cengiz Onbasli

Keyword(s):

Genetic Algorithm ◽

Raman Spectroscopy ◽

Strong Electric Field ◽

Surface Enhanced Raman Spectroscopy ◽

Raman Signal ◽

Sers Substrate ◽

Design Constraints ◽

Sers Substrates ◽

Surface Enhanced ◽

Surface Enhanced Raman

Surface-enhanced Raman spectroscopy (SERS) is a highly sensitive and molecule-specific detection technique that uses surface plasmon resonances to enhance Raman scattering from analytes. In SERS system design, the substrates must have minimal or no background at the incident laser wavelength and large Raman signal enhancement via plasmonic confinement and grating modes over large areas (i.e., squared millimeters). These requirements impose many competing design constraints that make exhaustive parametric computational optimization of SERS substrates prohibitively time consuming. Here, we demonstrate a genetic-algorithm (GA)-based optimization method for SERS substrates to achieve strong electric field localization over wide areas for reconfigurable and programmable photonic SERS sensors. We analyzed the GA parameters and tuned them for SERS substrate optimization in detail. We experimentally validated the model results by fabricating the predicted nanostructures using electron beam lithography. The experimental Raman spectrum signal enhancements of the optimized SERS substrates validated the model predictions and enabled the generation of a detailed Raman profile of methylene blue fluorescence dye. The GA and its optimization shown here could pave the way for photonic chips and components with arbitrary design constraints, wavelength bands, and performance targets.

Download Full-text

Optical integrated chips with micro and nanostructures for refractive index and SERS-based optical label-free sensing

Nanophotonics ◽

10.1515/nanoph-2015-0015 ◽

2015 ◽

Vol 4 (4) ◽

pp. 419-436 ◽

Cited By ~ 8

Author(s):

Liu Liu ◽

Mingliang Jin ◽

Yaocheng Shi ◽

Jiao Lin ◽

Yuan Zhang ◽

...

Keyword(s):

Refractive Index ◽

Detection Limit ◽

Raman Scattering ◽

Wave Number ◽

Resonance Structure ◽

Excitation Wavelength ◽

Raman Signal ◽

Label Free ◽

Sers Substrates ◽

Refractive Index Sensing

Abstract:Label-free optical biosensing technologies have superior abilities of quantitative analysis, unmodified targets, and ultrasmall sample volume, compared to conventional fluorescence-label-based sensing techniques, in detecting various biomolecules. In this review article, we introduce our recent results in the field of evanescent-wavebased refractive index sensing and surface enhanced Raman scattering (SERS)-based sensing, both of which are promising platforms for label-free optical biosensors. First, silicon-on-insulator (SOI) nanowire waveguide and metallic surface plasmon resonance (SPR)-based refractive index sensing are discussed. In order to improve the detection limit, phase interrogation techniques are introduced to these types of sensors based on prism-coupled SPR and SOI microring resonators. A detection limit in the order of 10−6 refractive index unit is achieved. Detection of 16.7 pM anti-IgG is also demonstrated based on the SPR devices. Second, SERS substrates based on various nanometallic structures are discussed. Metallic nanowire arrays and inverted nanopyramids and grooves with a thin metal surface are fabricated based on anisotropic wetetching of silicon substrates. Both structures have demonstrated a Raman signal enhancement on the order of 107. In order to improve the extraction efficiency of the Raman signal at a high wave number, a nano-bowtie array substrate is fabricated, which exhibits double resonances at both the excitation wavelength and the desired Raman scattering wavelength. Experimental results have shown that this double-resonance structure can further enhance the received Raman signal, as compared to conventional SERS substrates with only one resonance at the excitation wavelength.

Download Full-text

A universal strategy for the incorporation of internal standards into SERS substrate to improve the reproducibility of Raman signal

The Analyst ◽

10.1039/d1an01562a ◽

2021 ◽

Author(s):

Binyong Lin ◽

Yuanyuan Yao ◽

Yueliang Wang ◽

Palanisamy Kannan ◽

Lifen Chen ◽

...

Keyword(s):

Quantitative Analysis ◽

Influencing Factor ◽

Raman Signal ◽

Sers Substrate ◽

Internal Standards ◽

Sers Substrates ◽

The Poor ◽

Surface Enhanced ◽

Surface Enhanced Raman ◽

Enhanced Raman Scattering

The uneven distribution of metal nanoparticles is a vital influencing factor in the poor uniformity of Surface-enhanced Raman scattering (SERS) substrates, which is a challenge in SERS quantitative analysis. Recent...

Download Full-text

Preparation of ZnO nanoflowers for surface enhance Raman scattering applications

VNU Journal of Science Mathematics - Physics ◽

10.25073/2588-1124/vnumap.4369 ◽

2020 ◽

Vol 36 (1) ◽

Author(s):

Tuyen Nguyen Viet

Keyword(s):

Raman Scattering ◽

Self Assembly ◽

Noble Metals ◽

Zno Nanorods ◽

Raman Signal ◽

Sers Substrate ◽

Chemical Substances ◽

Sers Substrates ◽

Electromagnetic Enhancement ◽

Surface Enhanced Raman

Thanks to unique Raman spectra of chemical substances, a growing number of applications in environmental and biomedical fields based on Raman scattering has been developed. However, the low probability of Raman scattering hindered its potential development and thus, many different techniques were developed to enhance Raman signal. A key step of surface-enhanced Raman scattering technique is to prepare active SERS substrate from noble metals. The main enhancement mechanism is electromagnetic enhancement resulted from surface plasmon resonance. The disadvantages of nanoparticles based SERS substrates include high randomness due to self - assembly process of nanoparticles. Recently, a new kind of SERS substrates with order nanostructures of semiconductors combining with noble metals can serve as active SERS substrates, which are expected to possess high enhancement of Raman signals. In this study, ordered ZnO nanorods were first prepared by galvanic hydrothermal method and gold was sputtered on the as prepared ZnO nanomaterials to enhance Raman. Our SERS substrates exhibit promising high enhancement factors, and can detect chemical substances at concentration in nano molar range.

Download Full-text

Gold Nanocylinders on Gold Film as a Multi-spectral SERS Substrate

Nanomaterials ◽

10.3390/nano10050927 ◽

2020 ◽

Vol 10 (5) ◽

pp. 927 ◽

Cited By ~ 3

Author(s):

Wafa Safar ◽

Médéric Lequeux ◽

Jeanne Solard ◽

Alexis P.A. Fischer ◽

Nordin Felidj ◽

...

Keyword(s):

Visible Range ◽

Excitation Wavelength ◽

Sers Substrate ◽

Sers Signal ◽

Sers Substrates ◽

Gold Thin Film ◽

Surface Enhanced ◽

Surface Enhanced Raman ◽

Enhanced Raman Scattering ◽

20 Nm

The surface enhanced Raman scattering (SERS) efficiency of gold nanocylinders deposited on gold thin film is studied. Exploiting the specific plasmonic properties of such substrates, we determine the influence of the nanocylinder diameter and the film thickness on the SERS signal at three different excitation wavelengths (532, 638 and 785 nm). We demonstrate that the highest signal is reached for the highest diameter of 250 nm due to coupling between the nanocylinders and for the lowest thickness (20 nm) as the excited plasmon is created at the interface between the gold and glass substrate. Moreover, even if we show that the highest SERS efficiency is obtained for an excitation wavelength of 638 nm, a large SERS signal can be obtained at all excitation wavelengths and on a wide spectral range. We demonstrate that it can be related with the nature of the plasmon (propagative plasmon excited through the nanocylinder grating) and with its angular dependence (tuning of the plasmon position with the excitation angle). Such an effect allows the excitation of plasmon on nearly the whole visible range, and paves the way to multispectral SERS substrates.

Download Full-text

Prosperity to challenges: recent approaches in SERS substrate fabrication

Reviews in Analytical Chemistry ◽

10.1515/revac-2016-0027 ◽

2017 ◽

Vol 36 (1) ◽

Cited By ~ 10

Author(s):

Lei Ouyang ◽

Wen Ren ◽

Lihua Zhu ◽

Joseph Irudayaraj

Keyword(s):

Raman Spectroscopy ◽

Single Molecule ◽

Surface Enhanced Raman Spectroscopy ◽

Structural Features ◽

In Situ Monitoring ◽

Raman Signal ◽

Sers Substrate ◽

Basic Step ◽

Analytical Technique ◽

Sers Substrates

AbstractSurface-enhanced Raman spectroscopy (SERS) is a highly promising analytical technique that has been widely applied in health and environment monitoring. As a vibrational spectroscopic tool, its fingerprint spectrum contains abundant molecular information, and the greatly enhanced signal can be used to detect analytes at extremely low concentration, even down to the single molecule level. Because water molecules give very weak Raman response, Raman spectroscopy has also been applied for in situ monitoring of targets in solution. However, the Raman signal of an analyte could only be enhanced when it is in proximity to the SERS substrate, which enhances the signal depending on the shape, size, and orientation of the particles constituting the substrate. Further, when using the method for the detection of various analytes, it is necessary to functionalize the SERS substrates, with recognition ligands and encapsulation with a suitable shell among others. Hence, the fabrication of suitable substrates is a basic step in SERS-related research. Tremendous effort has been expended in the last decade in this area, resulting in the development of substrates with unique properties. In this review, we will introduce recent achievements in SERS substrate fabrication based on their structural features. Synthesized nanoparticles, two-dimensional planar substrates, and three-dimensional substrates with effective volume will be discussed in the context of their synthesis strategies along with their characteristic properties. In the future, with further improvement in SERS substrates, the applicability of SERS for detecting a range of analytes in complex environment will become possible.

Download Full-text

Study on the effect of Ag nanoparticles density on ZnO/Ag nanostructure to enhance raman signals of SERS substrate on abamectin

Science and Technology Development Journal - Natural Sciences ◽

10.32508/stdjns.v5i2.971 ◽

2021 ◽

Vol 5 (2) ◽

pp. first

Author(s):

Long Hoang Nguyen ◽

Thanh Ha Nguyen ◽

Tuan Anh Dao ◽

Ke Huu Nguyen ◽

Hung Vu Tuan Le

Keyword(s):

Ag Nanoparticles ◽

Chemical Elements ◽

Sol Gel ◽

Zno Nanorods ◽

Excitation Wavelength ◽

Diffraction Measurement ◽

Sers Substrate ◽

X Ray Diffraction ◽

X Ray ◽

Sers Substrates

This study investigated the effect of changing the density of Ag nanoparticles on the ZnO/Ag nanorod structure on the SERS substrate signal amplification ability. First, ZnO nanorods were fabricated by the sol - gel method combining with the chemical bath deposition method. Next, the Ag nanoparticles were decorated on ZnO nanorods by the DC magnetron sputtering method. The density and size of the modified Ag nanoparticles on the ZnO nanorods were changed by adjusting the sputtering times to 5, 10, 15 and 20s respectively. The optical properties of the material are characterized by UV - Vis and PL measurements. The surface morphology of ZnO nanorods and Ag nanoparticles were investigated by scanning electron microscope (SEM). X-ray diffraction measurement (XRD) is used to examine the crystal structures of materials. The composition and distribution of the chemical elements inside the material were investigated by Energy-dispersive X-ray spectroscopy (EDX). The ability of SERS substrates to amplify Raman signals was evaluated by measuring the R6G solution and investigating application for abamectin with a laser excitation wavelength of 532 nm. The results showed that SERS ZnO/Ag substrates with sputtering time of 15s gave the best ability to amplify SERS with the detection of R6G solution at 10􀀀9 M and abamectin at 50 ppm.

Download Full-text