Recent advances in linear and nonlinear Raman spectroscopy. Part IV

The purpose of the review is to provide a concise overview of recent advances in the broadly defined field of Raman spectroscopy as reflected in part by the many articles published each year in the Journal of Raman Spectroscopy (JRS) as well as in trends across all related journals publishing in this research area. Context for the review is provided by considering statistical data on citations for the Thompson Reuters ISI Web of Science by year and by subfield of Raman spectroscopy. Additional statistics of number of papers and posters presented by category at the XXII International Conference on Raman Spectroscopy (ICORS 2010) is also provided. Papers published in JRS in 2009, as reviewed here, reflect trends at the cutting edge of Raman spectroscopy which is expanding rapidly as a sensitive photonic probe of matter at the molecular level with an ever widening sphere of novel applications. Copyright © 2010 John Wiley & Sons, Ltd.     

Recent advances in linear and nonlinear Raman spectroscopy. Part VI

The purpose of this review is to provide a concise overview of recent advances in the broadly defined field of Raman spectroscopy as reflected in part by the many articles published each year in Journal of Raman Spectroscopy as well as in trends across all related journals publishing in this research area. Context for this review is derived from statistical data on article counts obtained from Thomson Reuters ISI Web of Knowledge by year and by subfield of Raman spectroscopy. Additional information is gleaned from presentations featuring Raman spectroscopy presented at the XXIII International Conference on Raman Spectroscopy in Bangalore, India, in August 2012 and at Scientific Exchange 2012 sponsored by the Federation of Analytical Chemistry and Spectroscopy Societies in Kansas City, Missouri, USA, October 2012. Papers published in the Journal of Raman Spectroscopy in 2011 are highlighted in this review and reflect trends at the cutting edge of Raman spectroscopy, a field that is expanding rapidly as a sensitive photonic probe of matter at the molecular level with an ever widening sphere of novel applications. Copyright © 2012 John Wiley & Sons, Ltd.     

Recent advances in linear and nonlinear Raman spectroscopy. Part VII

The aim of this paper is to provide an overview of advances in the field of Raman spectroscopy as reflected in articles published each year in the Journal of Raman Spectroscopy as well as in trends across related journals publishing in this research area. The context for this review is derived from statistical data on article counts obtained from Thomson Reuters ISI Web of Knowledge by year and by subfield of Raman spectroscopy. Additional information is gleaned from presentations featuring Raman spectroscopy presented at the International Conference on Advanced Vibrational Spectroscopy in Kobe Japan in August 2013 and at SCIX 2013 sponsored by the Federation of Analytical Chemistry and Spectroscopy Societies in Milwaukee, Wisconsin, USA, October 2013. Papers published in the Journal of Raman Spectroscopy in 2012 are highlighted in this review and reflect topics and advances at the frontier of Raman spectroscopy, a field that is expanding rapidly as a sensitive photonic probe of matter at the molecular level in an ever widening sphere of novel applications. Copyright © 2013 John Wiley & Sons, Ltd.     

Recent advances in linear and non‐linear Raman spectroscopy. Part IX

This annual review is published to provide an overview of advances in the field of Raman spectroscopy as reflected in papers published each year in the Journal of Raman Spectroscopy (JRS) as well as in trends across related journals that have published papers in the broad field of Raman spectroscopy. The content is obtained from statistical data on article counts obtained from Thomson Reuters ISI Web of Science Core Collection by year and by subfield of Raman spectroscopy. Additional information is gleaned from presentations at the VIII International Conference on Advanced Vibrational Spectroscopy (ICAVS‐8) in Vienna, Austria in July 2015 and those featuring Raman scattering at SCIX 2015 organized by the Federation of Analytical Chemistry and Spectroscopy Societies (FACSS) in Providence, Rhode Island, USA, in September/October 2015. Coverage is also provided for topics from the conference ECONOS 2015 held in April in Leuven, Belgium. Finally, papers published in JRS in 2014 are highlighted and arranged by topics at the frontier of Raman spectroscopy. Taken from these various viewpoints, it is clear that Raman spectroscopy continues to be a rapidly expanding field that provides sensitive photonic information of matter at the molecular level in an ever‐widening arena of novel applications. Copyright © 2015 John Wiley & Sons, Ltd.     

Recent advances in linear and non‐linear Raman spectroscopy. Part III

Following the first two reviews on recent advances in linear and non‐linear Raman spectroscopy, the present review summarises papers mainly published in the Journal of Raman Spectroscopy during 2008. This again serves to give a brief overview of recent advances in this research field and to provide readers of this journal a quick introduction to the various sub‐fields of Raman spectroscopy. It also reflects the current research interests and trends in the Raman community. Copyright © 2009 John Wiley & Sons, Ltd.     

Recent advances in linear and nonlinear Raman spectroscopy II

Following the first review on recent advances in linear and nonlinear Raman spectroscopy, the present review summarizes papers mainly published in the Journal of Raman Spectroscopy during 2007. This serves to give a fast overview of recent advances in this research field as well as to provide readers of this journal a quick introduction to the various subfields of Raman spectroscopy. It also reflects the current research interests of the Raman community. Similar reviews of highly active areas of Raman spectroscopy will appear in future issues of this journal. Copyright © 2008 John Wiley & Sons, Ltd.     

Recent Advances in linear and nonlinear Raman spectroscopy I

Raman spectroscopy has advanced considerably in the last several years due to rapid developments in instrumentation and the availability of theoretical methods for accurate calculation of Raman spectra, thus enormously facilitating the interpretation of Raman data. This review is restricted to cover papers mainly published in the Journal of Raman Spectroscopy, which serve to give a fast overview of recent advances in this research field as well as to provide readers of this journal a quick introduction to the various subfields of Raman spectroscopy. It also reflects the current research interests of the Raman community. Similar reviews of highly active areas of Raman spectroscopy will appear in future issues of this journal. Copyright © 2007 John Wiley & Sons, Ltd.     

Raman spectroscopy as a tool for detecting mitochondrial fitness

Raman spectroscopy allows the molecular chemical analysis of whole living cells by comparing them to known Raman signatures of specific vibrational bonds. In this work we used Raman spectroscopy to differentiate between wild type yeast cells and mutants characterized by increased or reduced mitochondrial fragmentation. To associate mitochondrial fragmentation with biochemical markers, we performed Linear Discriminant Analysis (LDA) of whole cell Raman spectra (~50–100 cells/spectrum). We show that the long‐lived, less fragmented mutants fall into a significantly distant cluster from the wild type and short‐lived, more fragmented mutants. Clustering depends on respiratory growth and coincides with that of membrane phospholipids and some respiratory chain components. Spectral clustering is supported by enzymatic activity measurements of OXPHOS Complexes. In addition, we find that NAD(P)H autofluorescence also correlates with mitochondrial fragmentation, representing another likely aging biomarker, besides phospholipids and OXPHOS components. In summary, we demonstrate that Raman spectroscopy has the potential to become a powerful tool for differentiating healthy from unhealthy aged tissues, as well as for the prognostic evaluation of mitochondrial function and fitness. © 2016 The Authors Journal of Raman Spectroscopy Published by John Wiley & Sons Ltd     

Study of Raman spectrum of uranium using a surface‐enhanced Raman scattering technique

Raman spectroscopic investigation on weak scatterers such as metals is a challenging scientific problem. Technologically important actinide metals such as uranium and plutonium have not been investigated using Raman spectroscopy possibly due to poor signal intensities. We report the first Raman spectrum of uranium metal using a surface‐enhanced Raman scattering‐like geometry where a thin gold overlayer is deposited on uranium. Raman spectra are detected from the pits and scratches on the sample and not from the smooth polished surface. The 514.5‐ and 785‐nm laser excitations resulted in the Raman spectra of uranium metal whereas 325‐nm excitation did not give rise to such spectra. Temperature dependence of the B_3g mode at 126 cm⁻¹ is also investigated. Copyright © 2011 John Wiley & Sons, Ltd.     

Vibrational Spectroscopy in Clinical Analysis

Abstract: Vibrational spectroscopy includes several different techniques, the most important of which are mid-infrared (IR), near-IR, and Raman spectroscopy. Raman and mid-IR spectroscopy are complementary techniques and usually both are required to completely measure the vibrational modes of a molecule. Vibrational spectrometry covers a series of well-established analytical methodologies suitable to be employed for both qualitative and quantitative purposes. In the first part of this review, we will focus on theoretical aspects related to vibrational techniques; in the second part, the most important papers, published during the period 2005–2014, related to clinical analysis performed with vibrational spectroscopy techniques will be critically discussed.     

Raman Spectroscopy of Biological Tissues

Abstract

We previously published a comprehensive review paper reviewing the Raman spectroscopy of biological molecules. This research area has expanded rapidly, which warranted an update to the existing review paper by adding the recently reported studies in literature. This article reviews some of the recent advances of Raman spectroscopy in relation to biomedical applications starting from natural tissues to cancer biology. Raman spectroscopy, an optical molecular detective, is a vibrational spectroscopic technique that has potential not only in cancer diagnosis but also in understanding progression of the disease. This article summarizes some of the most widely observed peak frequencies and their assignments. The aim of this review is to develop a database of molecular fingerprints, which will facilitate researchers in identifying the chemical structure of the biological tissues including most of the significant peaks reported both in the normal and cancerous tissues. It has covered a variety of Raman approaches and its quantitative and qualitative biochemical information. In addition, it covers the use of Raman spectroscopy to analyse a variety of different malignancies including breast, brain, cervical, gastrointestinal, lung, oral, and skin cancer. Multivariate analysis approaches used in these studies have also been covered.     

Applications of Raman spectroscopy in herbal medicine

Raman spectroscopic techniques are a group of chemical fingerprint detection methods based on molecular vibrational spectroscopy. They are compatible with aqueous solutions and are time saving, nondestructive, and highly informative. With complementary and alternative medicine (CAM) becoming increasingly popular, more people are consuming natural herbal medicines. Thus, chemical fingerprints of herbal medicines are investigated to determine the content of these products. In this study, I review the different types of Raman spectroscopic techniques used in fingerprinting herbal medicines, including dispersive Raman spectroscopy, resonance Raman spectroscopy, Fourier transform (FT)–Raman spectroscopy, surface-enhanced Raman scattering (SERS) spectroscopy, and confocal/microscopic Raman spectroscopy. Lab-grade Raman spectroscopy instruments help detect the chemical components of herbal medicines effectively and accurately without the need for complicated separation and extraction procedures. In addition, portable Raman spectroscopy instruments could be used to monitor the health and safety compliance of herbal products in the consumer market.     

Raman spectroscopy of dipyrrins: nonresonant,resonant and surface‐enhanced cross‐sections and enhancement factors

Detailed studies of the mechanism of surface‐enhanced (resonance) Raman spectroscopy (SE(R)RS), and its applications, place a number of demands on the properties of SERS scatterers. With large Raman cross‐sections, versatile synthetic chemistry and complete lack of fluorescence, free dipyrrins meet these demands but the Raman and SE(R)RS spectroscopy of free dipyrrins is largely unknown. The first study of the Raman spectroscopy of free dipyrrins is therefore presented in this work. The nonresonant Raman, resonant Raman and surface‐enhanced Raman spectra of a typical meso aryl‐substituted‐dipyrrin are reported. Absolute differential cross‐sections are obtained for excitation wavelengths in the near infrared and visible region, in solution phase and for dipyrrin adsorbed on the surface of silver nanoparticles. Raman enhancement factors for SERRS and resonance Raman are calculated from the observed differential cross‐sections. The magnitudes of the resonantly enhanced cross‐sections are similar to those recently reported for strong SERS dyes such as Rhodamine 6G and Crystal Violet. Free dipyrrins offer the advantages of existing SERS dyes but without the drawback of strong fluorescence. Free dipyrrins should therefore find applications in all areas of Raman spectroscopy including fundamental studies of the mechanisms of SERS and bioanalytical and environmental applications. Copyright © 2011 John Wiley & Sons, Ltd.     

Spectroscopic Trends for the Determination of Illicit Drugs in Oral Fluid

Abstract

The present work aims to review all of the articles published so far, focused on the determination of drugs of abuse in oral fluid. This fluid provides a simpler, faster, and more controllable sampling in comparison with the other biological fluids, such as blood or urine. Actually, the main goal of the researchers is to lower the limit of detection (LOD) to detect quantities of drugs smaller than the cut-off limits established by law for drug controls. Advances in Raman, infrared (IR), and nuclear magnetic resonance (NMR) spectroscopy applications are discussed. Surface-enhanced Raman spectroscopy (SERS) has been shown as the most sensitive technique for the detection of illicit drugs in oral fluid. The use of IR spectroscopy for determining drugs of abuse in oral fluid is growing, although the LODs obtained until now do not yet satisfy the necessities in the forensic field. Finally, NMR spectroscopy has seldom been used to determine drugs in oral fluid. Another future trend seems to be related with the use of portable instrumentation, which would allow us to perform in-situ analysis. This last application seems to be particularly promising to perform roadside drug tests and to identify overdose drugs in patients in emergency conditions.     

Fiber optic probes for linear and nonlinear Raman applications – Current trends and future development

This review focuses on fiber optic probes for linear and nonlinear Raman spectroscopy, especially for medical applications. It aims at providing an overview over contemporary technology, recent first clinical trials, and helps identifying future developments necessary to bring the emerging technology to clinical end users. After a short introduction to linear and nonlinear Raman spectroscopic modalities, general design considerations will be discussed and compared to common fiber probe setups. Subsequently, examples for medical applications of fiber optic Raman probes will be given concentrating on probes for linear Raman spectroscopy as these devices are technologically more mature compared to their counterparts based on nonlinear Raman spectroscopy. The review also includes a brief summary of first multimodal fiber optic probes and highlights their benefits for clinical applications. Finally, probes are introduced which employ either nonlinear Raman spectroscopy or surface enhanced spectroscopy.     

TLC原位拉曼光谱法快速检测减肥类保健食品中非法添加的四种成分

建立薄层色谱(TLC)与拉曼光谱联用方法,并对减肥类保健食品中非法添加的四种化学成分(茶碱、咖啡因、苯丙酸诺龙、螺内酯)进行检测。采用TLC法将掺杂成分与保健食品基质进行初步分离,在紫外灯(254 nm)下检视定位,以780 nm激光为光源,对TLC上微量掺杂成分的斑点原位,直接检测浓集点的拉曼光谱。考察不同配方保健食品基质对掺杂成分拉曼光谱的影响,并对检测限进行验证,初步建立了减肥类保健食品中四种掺杂成分的TLC原位拉曼光谱检测方法。常用保健食品基质对掺杂成分检测结果无干扰,检测限为2~4 μg,在九种减肥类保健食品中检测出两种含有咖啡因。该研究建立了TLC与拉曼光谱联用技术并采用此方法快速鉴别了减肥保健食品中茶碱等四种非法添加化学成分,本法专属、灵敏、快速、简便,可为保健食品中非法添加化学成分的快速检测技术研究提供新的参考依据。     

基于反向传播神经网络的拉曼光谱去噪方法

拉曼光谱技术作为一种典型的光学检测方法,因其独特的非侵入性、快速、原位和极高的特异性,在生物分析、疾病诊断及分子识别等众多领域得到广泛应用.拉曼光谱的指纹特性使其成为生物医学分析领域的重要工具,但拉曼散射信号微弱,数据处理分析大量依赖分析人员、自动化处理能力低等因素都会极大影响该技术在实际中的应用.实验设备、环境产生的...     

Passive signal enhancement in spatially offset Raman spectroscopy

We demonstrate experimentally, for the first time, the feasibility of enhancing signals in Spatially Offset Raman Spectroscopy (SORS) using a dielectric bandpass filter, building on our earlier experimental work on the enhancement of transmission Raman signals. The method is shown to lead to the enhancement of both the surface and subsurface Raman layer signal improving the signal‐to‐noise ratio of Raman spectra from the deep areas of samples, thus enhancing the technique's sensitivity and penetration depth. The filter is placed over the laser illumination zone, on the sample surface acting as a ‘unidirectional’ mirror transmitting the collimated laser beam on one side and reflecting photons escaping from the sample back into it. This enhances the degree of coupling of laser radiation into the medium and associated generated Raman signal. The feasibility study was performed on a two‐layer sample with the second layer located at the limit of the penetration depth of the method for this sample. The sample consisted of a 2.2‐mm over‐layer of a thinned paracetamol tablet followed by a 2‐mm layer of trans‐stilbene powder. The Raman signal was collected from a spatially offset region through a hole fabricated within the filter. The experiments demonstrate the presence of an enhancement of the Raman signal from both the layers by a factor of 4.4–4.5 and the improved signal‐to‐noise ratio of sublayer signal by a factor of 2.2, in agreement with photon shot noise dominated signal. Copyright © 2008 John Wiley & Sons, Ltd.     

表面增强拉曼光谱生物成像技术及其应用

基于表面增强拉曼光谱的成像分析方法具有频带窄,水溶液背景弱,稳定性好,高特异性等优势已成为生物成像领域的优良选择。拉曼成像技术拓展了拉曼光谱的应用范围,使其不再只是检测单点化学成分的手段,而进一步用于对评价区域内化学物质成分、分布及变化进行整体统计和描述。本文探讨了表面增强拉曼散射的原理及增强机制,介绍了基于表面增强拉曼光谱的拉曼成像技术,并对其在无标记成像及带标记成像中的细胞成像、活体成像,特别是其在生物医学方面的应用进行了详细论述,最后讨论了表面增强拉曼光谱生物成像技术存在的问题,展望了该项技术的研究和应用前景。     

Na_2SO_4溶液激光拉曼/激光诱导击穿光谱联合探测

光谱技术应用于海底极端环境下多参数、多相态、无接触探测已成为深海化学传感器发展的一个重要方向,尤其是水下激光拉曼光谱技术和水下激光诱导击穿光谱技术正成为目前研究开发的热点。该工作旨在探索一项水下激光诱导击穿光谱与激光拉曼光谱(LIBS-LRS)联合探测技术,以实现LIBS和拉曼两种检测技术在检测系统上的整合,在信息获取上的互补。在实验室搭建了一套LIBS-LRS联合探测装置,该装置对于拉曼和LIBS采用同样的激发光源、光谱仪和探测器,前置光路分为两部分:拉曼光路和LIBS光路,分别收集Na_2SO_4溶液的拉曼信号和LIBS信号。前置光路收集的拉曼和LIBS信号由Y型光纤导入光谱仪,分别在面阵CCD不同区域进行探测。利用该装置对配置的Na_2SO_4溶液进行探测,同时获得了Na元素的LIBS信号和SO~(2-)_4拉曼信号。另外,随着激光能量的提高,在532nm脉冲激光能量超过3.6mJ时,在拉曼光路同时获得了Na元素的LIBS信号和SO~(2-)_4拉曼信号,这样采用同一光路即可实现两种光谱技术的联合,然而实验发现,随着激光能量的增加,激光在溶液中击穿产生的轫致辐射造成了光谱探测基线整体的抬升,对拉曼光谱弱信号的探测是不利的。实验结果初步证明了在拉曼和LIBS在水下联合探测的可行性。