Raman Scattering Technique Research Articles

Non-specific/specific SERS spectra concatenation for precise bacteria classifications with few samples using a residual neural network

Deep learning neural network incorporating surface enhancement Raman Scattering technique (SERS) is becoming as a powerful tool for the precise classifications and diagnosis of bacterial infections. However, the large amount of sample requirement and time-consuming sample collection severely hinder its applications. We herein propose a spectral concatenation strategy for residual neural network using non-specific and specific SERS spectra for the training data augmentation, which is accessible to acquiring larger training dataset with same number of SERS spectra or same size of training dataset with fewer SERS spectra, compared with pure non-specific SERS spectra. With this strategy, the training loss exhibit rapid convergence, and an average accuracy up to 100% in bacteria classifications was achieved with 50 SERS spectra for each kind of bacterium; even reduced to 20 SERS spectra per kind of bacterium, classification accuracy is still > 95%, demonstrating marked advantage over the results without spectra concatenation. This method can markedly improve the classification accuracy under fewer samples and reduce the data collection workload, and can evidently enhance the performance when used in different machine learning models with high generalization ability. Therefore, this strategy is beneficial for rapid and accurate bacteria classifications with residual neural network.

Visualization of the Gas Spatial Distribution of the Odor Source by SERS Gas Sensor

Surface‐Enhanced Raman Scattering (SERS) technique is used to fabricate the gas sensor, which is developed for the visualization of the spatial distribution of gas evaporating from odor source. The 3 × 3 SERS sensor array is put on the odor source and then scanned by the home‐made detection system to obtain the Raman spectra of the odor. The intensities of the characteristic peaks from the collected spectra are used to draw a heatmap graph. After the heatmap graph is processed by the noise reduction, the localization of the odor source can be clearly identified through the resulting graph. © 2024 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC.

Time-Domain Coherent Raman Scattering Techniques (Invited)

Time-Domain Coherent Raman Scattering Techniques (Invited)

Conquering Metal–Organic Frameworks by Raman Scattering Techniques

AbstractMetal–organic frameworks (MOFs) have emerged as a versatile class of materials. Understanding the structural and chemical properties of MOFs is essential for tailoring their performance to suit specific applications. In recent years, Raman spectroscopy, a non‐destructive vibrational spectroscopic technique, has evolved into a powerful tool for characterizing MOFs. Beyond spontaneous Raman scattering, numerous advanced Raman techniques have been developed to amplify the inherently weak Raman signal. These innovations have significantly enhanced the spatial resolution, frame rate, and sensitivity of Raman imaging, thereby opening up new possibilities for applications, such as label‐free sensing. This tutorial work is designed to demystify the fundamental theory and instrumentation of Raman spectroscopy, elucidating the differences between commonly used Raman techniques. Particular emphasis is placed on their advantages and limitations when applied to MOF materials. Furthermore, this work showcases how Raman techniques are employed in studying MOF systems to address societal needs and explore future directions. Ultimately, this review emphasizes the crucial role of Raman spectroscopy and the development of novel Raman‐based in situ techniques to conquer the field of MOFs.

High-Accuracy Renal Cell Carcinoma Discrimination through Label-Free SERS of Blood Serum and Multivariate Analysis.

Renal cell carcinoma (RCC) represents the sixth most frequently diagnosed cancer in men and is asymptomatic, being detected mostly incidentally. The apparition of symptoms correlates with advanced disease, aggressive histology, and poor outcomes. The development of the Surface-Enhanced Raman Scattering (SERS) technique opened the way for investigating and detecting small molecules, especially in biological liquids such as serum or blood plasma, urine, saliva, and tears, and was proposed as a simple technique for the diagnosis of various diseases, including cancer. In this study, we investigated the use of serum label-free SERS combined with two multivariate analysis tests: Principal Component Analysis combined with Linear Discriminate Analysis (PCA-LDA) and Supported Vector Machine (SVM) for the discrimination of 50 RCC cancer patients from 45 apparently healthy donors. In the case of LDA-PCA, we obtained a discrimination accuracy of 100% using 12 principal components and a quadratic discrimination function. The accuracy of discrimination between RCC stages was 88%. In the case of the SVM approach, we obtained a training accuracy of 100%, a validation accuracy of 92% for the discrimination between RCC and controls, and an accuracy of 81% for the discrimination between stages. We also performed standard statistical tests aimed at improving the assignment of the SERS vibration bands, which, according to our data, are mainly due to purinic metabolites (uric acid and hypoxanthine). Moreover, our results using these assignments and Student's t-test suggest that the main differences in the SERS spectra of RCC patients are due to an increase in the uric acid concentration (a conclusion in agreement with recent literature), while the hypoxanthine concentration is not statistically different between the two groups. Our results demonstrate that label-free SERS combined with chemometrics holds great promise for non-invasive and early detection of RCC. However, more studies are needed to validate this approach, especially when combined with other urological diseases.

Concentration dependent SERS profile of p-tolyl 2-acetamido-3-(4-fluorophenyl)propanoate (AFP) in silver colloidal nanohydrosols: Experimental and DFT investigations

Based on Density Functional Theory (DFT) calculations and the Surface Enhanced Raman Scattering (SERS) technique, the adsorption properties of p-tolyl 2-acetamido-3-(4-fluorophenyl)propanoate (AFP) on silver surface were examined. The title compound, AFP showed balanced inhibition of acetyl- and butyrylcholinesterase along with mild cytotoxicity of HepG2 cells according to the previous study. After adsorption on silver surface, the structural properties of AFP exhibit a small modification, indicating an interaction between the AFP and Ag6 cluster. Experimental research on AFP and SERS spectra at various concentrations was conducted. Raman frequencies for AFP and AFP adsorbed on silver were computed. FMOs for AFP and AFP adsorbed on the silver surface were conducted. After AFP was adsorbed on the silver, the energy gap was dramatically lowered. The greater bioactivity of AFP is caused by the lowering energy gap, which denotes the electron delocalization. According to SERS spectrum analysis, AFP was adsorbed on silver with a tilted orientation. As a result, the current study has been used as a model system to comprehend how silver nanoprticles (NP) interact with AFP. Silver nanoparticles are successfully used for the treatment of different diseases alone or in association with other active components and the incorporation of AFP with silver nanocolloids will act as a nanodrug delivery system.

Molecularly Imprinted Plasmonic Sensors for the Determination of Environmental Water Contaminants: A Review

The scarcity of clean water leads to the exploration of the possibility of using treated wastewater. However, monitoring campaigns have proven the presence of emerging contaminants, such as pharmaceuticals, pesticides and personal care products, not only in trace amounts. Various analytical methodologies have been developed over the last years for the quantification of these compounds in environmental waters. Facing the need to achieve a higher sensitivity, fast response and practical use via miniaturization, the potential of plasmonic sensors has been explored. Through the introduction of molecularly imprinted polymers (MIPs) as recognition elements, MIP-based plasmonic sensors seem to be a good alternative for monitoring a wide range of analytes in water samples. This work attempts to provide a general overview of this form of sensor, which has been reported as being able to sense different contaminants in waters using surface plasmon resonance (SPR) and surface-enhanced Raman-scattering (SERS) techniques. Particular emphasis is given to the fabrication/recognition procedure, including the preparation of MIPs and the use of metals and nanomaterials to increase the performance characteristics of the sensors.

The orbital effect on the anomalous magnetism and evolution in LaxY1-xVO3 (0 ≤ x ≤ 0.2) single crystals

The orbital effect on the anomalous magnetism and evolution of single crystals with low La doping, LaxY1−xVO3 (x = 0, 0.1, and 0.2), has been studied using single-crystal X-ray diffraction, specific heat, magnetization, and Raman-scattering techniques. It is found that substituting Y3+ by La3+ increases the degeneracy of the yz/zx orbitals and decreases the Jahn-Teller distortion. These weakens the G-type (antiphase ordering along the c axis) orbital ordering phase. Meanwhile, the substituting decreases the magnetism entropy, indicating the shrinking of the t2g and eg orbital hybridization, eventually destabilizing the C-type (in-phase ordering along the c axis) antiferromagnetic ordering phase. In addition, the mechanism for the shrinking of the diamagnetism with increasing x is analyzed. It may attribute to the competition between the antisymmetric Dzyaloshinsky–Moriya interaction and the single-ion anisotropy.

Gold Nanoparticles are Capped Under the Irmof-3 Platform for In-Situ Surface-Enhanced Raman Scattering Technique and Optic Fiber Sensor

Gold Nanoparticles are Capped Under the Irmof-3 Platform for In-Situ Surface-Enhanced Raman Scattering Technique and Optic Fiber Sensor

SERS Gas Sensors Based on Multiple Polymer Films with High Design Flexibility for Gas Recognition.

The Surface-Enhanced Raman Scattering (SERS) technique is utilized to fabricate sensors for gas detection due to its rapid detection speed and high sensitivity. However, gases with similar molecular structures are difficult to directly discriminate using SERS gas sensors because there are characteristic peak overlaps in the Raman spectra. Here, we proposed a multiple SERS gas sensor matrix via a spin-coating functional polymer to enhance the gas recognition capability. Poly (acrylic acid) (PAA), Poly (methyl methacrylate) (PMMA) and Polydimethylsiloxane (PDMS) were employed to fabricate the polymer film. The high design flexibility of the two-layer film was realized by the layer-by-layer method with 2 one-layer films. The SERS gas sensor coated by different polymer films showed a distinct affinity to target gases. The principle component analysis (PCA) algorithm was used for the further clustering of gas molecules. Three target gases, phenethyl alcohol, acetophenone and anethole, were perfectly discriminated, as the characteristic variables in the response matrix constructed by the combination of gas responses obtained 3 one-layer and 3 two-layer film-coated sensors. This research provides a new SERS sensing approach for recognizing gases with similar molecular structures.

A Spectral Resolution study in Femtosecond Stimulated Raman Scattering Microscopy

The simultaneous mapping and the specificity of different chemical species are desirable in several biological and biomedical applications. The stimulated Raman Scattering technique is a proven and well-established label-free method to map the distributions of individual species in a multi-component-based system due to the linear dependence of signals on concentration and its chemical selectivity. In this framework, spectral resolution, i.e., the ability to distinguish closely lying resonances, plays a fundamental role. Here in this work, the cross-correlation of Ti:Sa & OPO femtosecond laser beams in a stimulated Raman scattering microscope is measured. The separation between protein and lipid bands in the C-H region is important for biochemical research and is successfully classified.

Raman Scattering Techniques for Defense and Security Applications.

ADVERTISEMENT RETURN TO ISSUEPREVReviewNEXTRaman Scattering Techniques for Defense and Security ApplicationsAdam P. ListerAdam P. ListerSchool of Chemistry and Institute for Life Sciences, University of Southampton, Highfield, Southampton SO17 1BJ, United KingdomMore by Adam P. ListerView Biography, William J. SellorsWilliam J. SellorsDstl Porton Down, Salisbury SP4 0JQ, United KingdomMore by William J. SellorsView Biography, Chris R. HowleChris R. HowleDstl Porton Down, Salisbury SP4 0JQ, United KingdomMore by Chris R. HowleView Biography, and Sumeet Mahajan*Sumeet MahajanSchool of Chemistry and Institute for Life Sciences, University of Southampton, Highfield, Southampton SO17 1BJ, United Kingdom*Email: [email protected]More by Sumeet MahajanView Biographyhttp://orcid.org/0000-0001-8923-6666Cite this: Anal. Chem. 2021, 93, 1, 417–429Publication Date (Web):December 22, 2020Publication History Published online22 December 2020Published inissue 12 January 2021https://doi.org/10.1021/acs.analchem.0c04606Copyright © 2020 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views1275Altmetric-Citations8LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit Read OnlinePDF (2 MB) Get e-AlertsSUBJECTS:Bacteria,Lasers,Materials,Raman scattering,Raman spectroscopy Get e-Alerts

Mammalian cell and tissue imaging using Raman and coherent Raman microscopy.

Direct imaging of metabolism in cells or multicellular organisms is important for understanding many biological processes. Raman scattering (RS) microscopy, particularly, coherent Raman scattering (CRS) such as coherent anti-Stokes Raman scattering (CARS) and stimulated Raman scattering (SRS), has emerged as a powerful platform for cellular imaging due to its high chemical selectivity, sensitivity, and imaging speed. RS microscopy has been extensively used for the identification of subcellular structures, metabolic observation, and phenotypic characterization. Conjugating RS modalities with other techniques such as fluorescence or infrared (IR) spectroscopy, flow cytometry, and RNA-sequencing can further extend the applications of RS imaging in microbiology, system biology, neurology, tumor biology and more. Here we overview RS modalities and techniques for mammalian cell and tissue imaging, with a focus on the advances and applications of CARS and SRS microscopy, for a better understanding of the metabolism and dynamics of lipids, protein, glucose, and nucleic acids in mammalian cells and tissues. This article is categorized under: Laboratory Methods and Technologies > Imaging Biological Mechanisms > Metabolism Analytical and Computational Methods > Analytical Methods.

Rapid Detection of Cypermethrin by Using Surface-Enhanced Raman Scattering Technique

Cypermethrin is a toxic pesticide in the pyrethroid group. A Surface Enhanced Raman Scattering (SERS) based sensor has been developed to achieve simple pesticide sensing. In this work, rapid detection of cypermethrin by using the handheld Raman spectroscopy coupled with SERS substrate was demonstrated. SERS-active silver nanorods substrate was used to enhance Raman signals of test samples. The effect of exposure time and drop volume of sample was studied for cypermethrin measurement. The results found that the silver nanorods substrate can be used to measure cypermethrin in the range of 10-6 to 10-3 M with a handheld Raman spectrometer. Furthermore, the Raman signal of cypermethrin was confirmed by measuring solid cypermethrin with the standard Raman spectrometer. SERS substrate was competent to detect cypermethrin with a limit of detection (LOD) of 10-6 M.

An analysis of tetrahydrocannabinol (THC) and its analogs using surface enhanced Raman Scattering (SERS)

We present an analysis of the adsorption geometry of THC and its analogs (cannabinol, cannabidiol and HU-210) on silver using Surface Enhanced Raman Scattering (SERS) technique along with DFT calculations. Our study shows that these cannabinoids are oriented parallel to the silver surfaces and form bonds using primarily the benzene rings and oxygen atoms. In addition, we examine the effect of four different salts: MgCl2; MgSO4; KNO3; and Na2SO4 on SERS enhancements of these drugs. We observe that MgCl2 causes the greatest enhancement for most of these drugs. We attribute this enhancement to the increase of the electric field induced by Mg2+ salts and the formation of SERS active sites. This work also provides evidence that each salt most likely affects the orientation of all four cannabinoids in a similar way on a silver surface, resulting in a production of similar SERS spectra.

Raman Characterization of polycrystalline barium hexaferrite nanoparticles: SERS of nanoparticles in powder form

Raman Characterization of Materials in powder form has always remained challenging because of low signal to noise ratio. We, herein, propose a method to make use of Surface Enhanced Raman Scattering (SERS) technique to improve the usefulness of Raman study of powder samples containing particles of sub wavelength size. As a case study, we have successfully applied the method to barium hexaferrite (BHF) synthesized by the modified citrate sol-gel method. The crystal structure and surface morphology of the prepared BHF powder were characterized by X-ray diffraction (XRD) and scanning electron microscopy. As many as 19 Raman peaks in a single spectrum with unpolarized laser were observed in the present work, against the commonly observed (in literature) 10–12 peaks for BHF. This report, as it is believed, will enable the research community to probe further into the distortions in crystal structure through Raman studies.

Raman Scattering in AlN Crystals Grown by Sublimation on SiC and AlN Seeds

The Raman-scattering technique is used to analyze the structural quality of bulk AlN crystals grown by sublimation on SiC and AlN seeds. Growth on SiC seeds is conducted with retention of the SiC seed during growth (type 1) and with total evaporation of the SiC seed (type 2). Growth on AlN seeds is conducted in tungsten containers with no graphite parts (type 3). According to the analysis of Raman spectra, the highest quality is inherent in type-3 crystals that exhibit minimal full widths at half maximum of Raman lines. The experimentally observed specific features are defined by differences in the mechanism of growth and by the content of dopant impurities in the crystals grown.

Raman spectroscopic characterization of anti-diabetic drug metformin hydrochloride

Raman scattering spectra of metformin hydrochloride, one of the most widely used oral anti-diabetic drugs which also possesses anti-aging and anti-tumor properties, have been obtained by high-resolution and high-sensitivity Raman-scattering technique. It is established that rather narrow (4–10 cm–1) spectral lines of molecular vibrations are observed in of the metformin hydrochloride pressed powder sample in the important spectral range of 50–1700 cm–1. These “fingerprints” can be applied to reveal which chemical bonds produce spectral components corresponding to the vibrations of particular functional groups and the presence of crystalline state of the metformin hydrochloride without evidence of an amorphous phase. This observation makes the metformin hydrochloride as promising model system for development and application as molecular biosensors.

A facile seed growth method to prepare stable Ag@ZrO2 core-shell SERS substrate with high stability in extreme environments.

A stable substrate is extraordinarily important for the trace detection of Surface Enhanced Raman Scattering technique. We have designed in this paper a simple seed growth method to prepare Ag@ZrO2 core-shell nanoparticles as well as regulate the core-shell ratio by adjusted concentration of zirconium propoxides added. The shell thickness effect and spacing on SERS activities have been simulated in different finite time domains, which goes perfectly with those previous experiment results. With Ag@ZrO2 core-shell nanoparticles adopted as the SERS substrate and R6G as molecular probe, the detection range could reach as great as 10-8 M. The regression model, obtained through principal component analysis, is adopted for some rapid and precise detection; and the determination coefficient (R2) is going up to 0.9743, proving that the SERS substrate we have prepared has extremely high detection accuracy. To explore the stability of core-shell nanoparticles, we have taken both two different cases of strong acid solution as well as strong alkali solution for the core-shell nanoparticle etching, and this is how a SERS test could be carried out. These experimental results have indicated that the outer zirconia layer could keep the silver surface from oxidation and its stability is ensured, quite crucial for the applied SERS.

PreS1 peptide-functionalized gold nanostructures with SERRS tags for efficient liver cancer cell targeting

Early detection is the most effective mean of improving prognosis for many fatal diseases such as cancer. In this context, the Surface Enhanced Resonance Raman Scattering (SERRS) technique is being proposed as alternative to fluorescent methods in detection of biomarkers, because SERRS nanostructures are bright as fluorescent tags but more stable and clearly detectable using the narrow Raman “fingerprints” of a suitable reporter. Here we show that biocompatible SERRS active gold nanostructures, functionalized with an engineered PreS1 peptide (AuNP@PEG-PreS1), detect the presence of the SerpinB3 antigen overexpressed on liver tumor cells, a biomarker of the onset of liver cell carcinomatous transformation. A proper engineering of the targeting unit, linked to the nanostructure by a polymer chain, affords a sensitivity and specificity larger than 80%, at subnanomolar concentrations. Taking into account the high sensitivity of SERRS and that SB3 overexpression is an early event in liver cell carcinomatous transformation, AuNP@PEG-PreS1 nanostructures could be used in routine diagnostic activities, to improve the accuracy of HCC detection in particular in patients with chronic liver diseases.