Application of Monodisperse Thermo-Responsive Composite Microgels with Core-Shell Structure Based on Au@Ag Bimetallic Nanorod as Core in Surface Enhanced Raman Spectroscopy Substrate

The monodisperse Au@Ag bimetallic nanorod is encapsulated by crosslinked poly( N-isopropylacrylamide)( PNIPAM) to produce thermo-responsive composite microgel with well-defined core-shell structure( Au@ Ag NR@ PNIPAM microgel)by seed-precipitation polymerization method using butenoic acid modified Au @ Ag NRs as seeds. When the temperature of the aqueous medium increases from 20℃ to 50℃,the localized surface plasmon resonance( LSPR) band of the entrapped Au @ Ag NR is pronouncedly red-shifted because of the decreased spatial distances between them as a result of shrinkage of the microgels,leading to their plasmonic coupling. The temperature tunable plasmonic coupling is demonstrated by temperature dependence of the surface enhanced Raman spectroscopy( SERS) signal of 1-naphthol in aqueous solution. Different from static plasmonic coupling modes from nanostructured assembly or array system of noble metals,the proposed plasmonic coupling can be dynamically controlled by environmental temperature. Therefore, the thermo responsive hybrid microgels have potential applications in mobile LSPR or SERS microsensors for living tissues or cells.

THE CHARACTERIZATION OF SILVER SUBCOLLOID USED IN SURFACE ENHANCED RAMAN SPECTROSCOPY

A clear light-yellow silver sol which has the visible spectral absorption at 390 nm, when adsorbed phenylmercaptotetrazole(PMT) or mercaptobenzothiazole(MBT), has a new absorption at 510-550 nm. It was found that the adsorption of halide ions competes with PMT and MBT. However, halide ions have a completely different influence from PMT and MBT on the spectral absorption of the silver sol. The differences may result from the change of the properties of the surface of the silver subcolloidal particles and from the bond forms combining adsorbates with the substrates.

Role of Raman spectroscopy and surface enhanced Raman spectroscopy in colorectal cancer

Colorectal cancer(CRC) is the fourth most commoncancer in the United Kingdom and is the second largest cause of cancer related death in the United Kingdom after lung cancer.Currently in the United Kingdom there is not a diagnostic test that has sufficient differentiation between patients with cancer and those without cancer so the current referral system relies on symptomatic presentation in a primary care setting.Raman spectroscopy and surface enhanced Raman spectroscopy(SERS) are forms of vibrational spectroscopy that offer a nondestructive method to gain molecular information about biological samples.The techniques offer a wide range of applications from in vivo or in vitro diagnostics using endoscopic probes,to the use of micro-spectrometers for analysis of biofluids.The techniques have the potential to detect molecular changes prior to any morphological changes occurring in the tissue and therefore could offer many possibilities to aid the detection of CRC.The purpose of this review is to look at the current state of diagnostic technology in the United Kingdom.The development of Raman spectroscopy and SERS in clinical applications relation for CRC will then be discussed.Finally,future areas of research of Raman/SERS as a clinical tool for the diagnosis of CRC are also discussed.

Design and Fabrication of Plasmonic Nanostructures with DNA for Surface-Enhanced Raman Spectroscopy Applications

Plasmonic nanostructures display unique and strongly enhanced optical properties, therefore hold great promise for a wide range of spectroscopic applications, particularly surface-enhanced Raman spectroscopy （SERS）. It is well acknowledged that the major contributions to SERS arise from molecules positioned in nanojunctions where the op- tical field is intensively concentrated due to localized surface plasmon excitations. One of the key challenges in SERS therefore lies in the design and fabrication of plasmonic nanostructures with controllable nanojunctions. In recent years, by exploiting the unparalleled base-pairing self-recognition properties, DNA-mediated assembly has emerged as a powerful and programmable tool for the accurate construction of complex and hierarchical plasmonic nanostructures with well-defined geometry and topology. In this review, we will summarize recent advances on de- sign and fabrication of a rich variety of plasmonic nanostructures by virtue of DNA nanotechnology, and discuss their optical properties as well as applications in SERS.

Synthesis of magnetic polyphosphazene-Ag composite particles as surface enhanced Raman spectroscopy substrates for the detection of melamine

Magnetic polyphosphazene(MPZS) particles coated by Ag nanoparticles(MPZS-Ag) have been developed as surface enhanced Raman spectroscopy(SERS) substrates for sensitive detection of melamine in aqueous solutions and milk samples.5,5’-Dithiobis-(2-nitrobenzoic acid)(DTNB) was used as model analyte to test the SERS activity of the MPZS-Ag particles.The prepared MPZS-Ag particles possess both magnetic responsiveness and excellent SERS properties.SERS detection of different concentrations of melamine aqueous solutions and spiked milk samples were performed by the MPZS-Ag particles.The limit of detection(LOD) of the melamine in aqueous solutions was 10^-7 mol/L(0.0126 mg/L) and 0.6 mg/L in real milk samples using the MPZS-Ag particles as SERS substrates.The LOD of the melamine are much lower than the safety values of Food and Drug Administration and Codex Alimentarius Commission.These results indicate that the MPZS-Ag particles have promising application prospect for SERS analysis in food safety fields.

Detection of chlorpyrifos in apples using gold nanoparticles based on surface enhanced Raman spectroscopy

In this study,gold nanoparticles(AuNPs)were synthesized for rapid and sensitive characterization and quantification of chlorpyrifos in apples.Min-max signal adaptive zooming and second derivative transformation method were adopted to pre-process Raman spectral signal.The min-max signal adaptive zooming method showed a higher correlation coefficient than derivative transformation when developing linear calibration curve between chlorpyrifos pesticide and Raman spectral peak intensity.The present method had a high reproducibility with the relative standard deviation less than 15%.Regression models showed a good linear relationship(R=0.962)between intensity of characteristic spectral peaks(at 677 cm-1)and chlorpyrifos concentration on whole apples ranging from 0.13 mg/kg to 7.59 mg/kg.The application of surface enhancement Raman spectroscopy(SERS)detected chlorpyrifos pesticide to the detection limit of 0.13 mg/kg,which can be applied further for lower concentration in the future.The method presented in this study can provide a way-out for detection of pesticide residue in whole apple to trace amount.

Sensitive and Label-Free Detection of Protein Secondary Structure by Amide Ⅲ Spectral Signals using Surface-Enhanced Raman Spectroscopy

Proteins and peptides perform a vital role in living systems, however it remains a challenge for accurate description of proteins at the molecular level. Despite that surface-enhanced Raman spectroscopy (SERS) can provide the intrinsic fingerprint information of samples with ultrahigh sensitivity, it suffers from the poor reproducibility and reliability. Herein, we demonstrate that the silver nanorod array fabricated by an oblique angle deposition method is a powerful substrate for SERS to probe the protein secondary structures without exogenous labels. With this method, the SERS signals of two typical proteins (lysozyme and cytochrome c) are successfully obtained. Additionally, by analyzing the spectral signals of the amide Ⅲ of protein backbone, the influence of concentration on the folding status of proteins has been elucidated. With the concentration increasing, the components of α-helix and β-sheet structures of lysozyme increase while the secondary structures of cytochrome c almost keep constant. The SERS method in this work offers an effective optical marker to characterize the structures of proteins.

Surface-enhanced resonance Raman scattering spectroscopy of single R6G molecules

Surface-enhanced resonance Raman scattering （SERRS） of Rhodamine 6G （R6G） adsorbed on colloidal silver clusters has been studied. Based on the great enhancement of the Raman signal and the quench of the fluorescence, the SERRS spectra of R6G were recorded for the samples of dye colloidal solution with different concentrations. Spectral inhomogeneity behaviours from single molecules in the dried sample films were observed with complementary evidences, such as spectral polarization, spectral diffusion, intensity fluctuation of vibrational lines and even ＂breathing＂ of the molecules. Sequential spectra observed from a liquid sample with an average of 0.3 dye molecules in the probed volume exhibited the expected Poisson distribution for actually measuring 0, 1 or 2 molecules. Difference between the SERRS spectra of R6G excited by linearly and circularly polarized light were experimentally measured.

Rapid Identification of Legionella Pathogenicity by Surface-Enhanced Raman Spectroscopy

Objective To establish Surface-enhanced Raman Spectroscopy（SERS） can be used as a rapid and reliable method to distinguish virulent strain and mild strain of L. pneumophila. Methods We isolated and characterized of bacterial strains from ATCC and water samples strains, while we analyzed data from SERS technology using gold nanoparticles as a base and cell infections were employed to rapidly detect L. pneumophila strains. Origin 8.0 was used to collect Raman spectra, smooth and homogenize data, and to contrast spectra. Principal component analysis（PCA） was conducted to discriminate differences between groups using the multivariate analysis package Py Chem 3.0.5. Results Our results indicated that the peaks of high virulence strains reached ≥4000. This criterion was verified by subsequent cell experiments. In addition, we also conducted SERS rapid identification on the virulence of several collected clinical strains and obtained accurate results. Conclusion The present study indicates that the established SERS protocol can be used as a rapid and reliable method to distinguish virulent and mildly virulent strains of L. pneumophila, which can be further used in clinical samples.

Monitoring the penetration and accumulation of gold nanoparticles in rat skin ex vivo using surface-enhanced Raman scattering spectroscopy

Contamination by accidental cutaneous contact with the commercial products and the air pol-hutants raised a considerable health and safety issue.This study aimed to trace the dynamics of the 20 nm gold nanopartide(GNP)penetration and accumulation in rat skin tissues using a surface-enhanced Raman scattering(SERS)techmique.After the topical application of GNPs on rat skin surface,the SERS spectra were recorded for every 15 pum to an overall depth of 75 pum from skin surface for 150 min.The processes of GNP penetration in rat skin were accompanied by aggregation of GNPs,which affected SERS spectra.The results revealed that 20 nm GNPs can penetrate through stratum corneum layer,viable epidermis layer,and then into dermis layer.This study demonstrated for the first time the potential of SERS spectroscopy to monitor the penetration and accumulation of GNPs in rat skin.

Structure of water at ionic liquid/Ag interface probed by surface enhanced Raman spectroscopy

The potential-dependent adsorption behavior of water and ionic liquid was probed by surface-enhanced Raman spectroscopy (SERS) at the Ag electrode surface in the ionic liquids containing water with different concentrations.The configuration of water at the ionic liquid/electrode interface and the relationship between the potential of zero charge (pzc) and the molar fraction of water were deduced through the changes in the vibrational frequency of OH stretching mode.A small Stark effect value was determined in the system with lower molar fraction of water.With the increase of the water concentration,the OH stretching vibrational frequency gradually shifted to the high wavenumber region,the pzc was also moved positively,and the Stark effect value of OH stretching vibrational mode increased.It reached about 76 cm-1 V-1 in the 1 mol L-1 [BMIM]Br aqueous solution.These differences were mainly contributed by hydrogen bonding and the configuration of water in the ionic liquid solution.In the solution with lower water content,water molecules existed at the interface layer through hydrogen bonding with cations,while in the higher content solution,the intermolecular hydrogen bonding between water molecules was strengthened and the possibility of the direct interaction between the water molecule and electrode surface increased.

基于表面增强拉曼光谱的牛肝菌主成分分析及快速鉴定

2021年《中国疾病预防控制中心周报》指出蘑菇中毒是我国最严重的食品安全问题之一,2021年发生蘑菇中毒事件327次,涉及923例患者,其中20例死亡,总死亡率为2.17%,事件中共鉴定出毒蘑菇74种。牛肝菌由于味道鲜美,是人们最喜爱的菌类之一。由于烹调不当或是混入有毒牛肝菌,就会发生牛肝菌中毒事件。如何快速得出牛肝菌的主成分并进行鉴定,成为了一个迫切需要解决的问题。该研究从楚雄市鸿福农贸市场上购买的10个新鲜牛肝菌样品,使用菌盖进行徒手切片,用微波法制备的纳米银溶胶制成银胶装片,置于DXR显微拉曼光谱仪的10倍物镜下,获得10个样品的表面增强拉曼光谱(SERS)。通过对SERS的分析发现10个样品中,样品7、8、10主成分相同,样品6、9主成分相同,其余样品主成分各不相同。以样品1为例,主成分有L-苯基丙氨酸(1583 cm^(-1)环内C—C伸缩振动、1199 cm^(-1)NH 2摇摆振动)、L-组氨酸(1572 cm^(-1)C C伸缩振动、COO-不对称伸缩、1229 cm^(-1)面内环变形振动)、异亮氨酸(1342 cm^(-1)C—H、N—H变形振动、486 cm^(-1)COOH摇摆振动、353 cm^(-1)骨架振动)、L-天冬氨酸(1136 cm^(-1)C—N伸缩振动)、甘氨酸(1386 cm^(-1)COO-变形振动、889 cm^(-1)C—C伸缩振动)、蛋氨酸(681 cm^(-1)C—S反对称伸缩振动)、吡喃糖化幌物(973 cm^(-1)对称环振动)。采用光谱软件OMNIC Specta的建库功能随机挑选10个样品的一条谱线进库,建库后可快速进行光谱匹配度的检索,通过匹配度的高低鉴定待测样品。在10个样品中,除2、10号样品的匹配度小于60%外,其余样品的匹配度都大于60%。样品7、8的匹配度接近且有交叉,说明样品7、8是同一品种,而样品6、9的匹配度接近而交叉项少,说明这两个样品是同一品种或相近品种。DNA检测结果表明样品7、8、10同为白牛肝菌,而样品6、9同为薄瓤假美柄牛肝菌。该实验为牛肝菌的主要成分检测和快速鉴定提供了一种简单可靠的方法。同时,该方法对野生蘑菇的物种鉴定具有很大的应用潜力,在野生菌中毒病例中,迅速确定毒蘑菇种类,从而为抢救病人赢得时间具有重要的意义。为此首次对野生蘑菇子实体进行SERS研究。

柠檬汁还原法制备AgNPs用于果蔬农药残留的SERS快速检测

[目的/意义]为满足目前市场上对农产品农药残留的快速灵敏检测需求,报道一种基于柠檬汁还原制备银纳米粒子(AgNPs)的方法。[方法]首先将新鲜柠檬汁经滤纸过滤,稀释成2%的柠檬汁水溶液,再配制一定浓度的AgNO3溶液、50 mM的NaOH溶液,放置室温保存。然后在室温下,将10 mL的ddH2O、2mL的NaOH、2mL的2%柠檬汁和5 mL的AgNO3溶液混合,待溶液颜色变为澄清的黄色时,溶液离心即可获得AgNPs。[结果和讨论]该方法制备的AgNPs,其颗粒形貌大小基本均一,约为20 nm,具有很好的表面增强拉曼散射(Surface Enhancement of Raman Scattering,SERS)增强效应,即良好的SERS信号稳定性,较强的SERS增强性能。该胶体中AgNPs分散较均匀,并且具有较长时间储存的稳定性,因此可用于微量农残检测。柠檬汁中主要还原成分抗坏血酸、葡萄糖和果糖,其含量分别为395.76μg/mL、5.95 mg/mL和5.90 mg/mL。将柠檬汁还原法制备的AgNPs用于果蔬表面农残检测,对于百草枯、多菌灵的检出限分别最低至3.90 ng/kg及0.22μg/kg。[结论]这项工作为果蔬农残快检提供了一种绿色、便捷的SERS材料制备方法,为实现农产品农药残留的快速、灵敏检测提供一种新的途径。

基于表面增强拉曼光谱的肾结石患者体液代谢谱特点及应用价值

目的分析基于表面增强拉曼光谱(SERS)的肾结石患者体液代谢谱特点,探讨其应用价值,为肾结石患者的筛查工作提供参考。方法纳入福建省立医院泌尿外科确诊的25例肾结石患者(结石组)和25例健康体检者(对照组),采集其血液、尿液样本,利用SERS测量样本光谱,再进行平均谱和差异谱绘制。采用主成分分析结合线性判别分析(PCA-LDA)对归一化数据进行处理。最后采用受试者工作特征(ROC)曲线评估PCA-LDA方法的效能。结果结石组患者的体液(血液、尿液)拉曼光谱与对照组之间存在差异。根据既往报道的拉曼峰暂定分配,推测血浆和尿液中各有11种代谢物与肾结石有关,其中结石组尿液中的磷脂酰肌醇、苯丙氨酸、棕榈酸/脂肪酸等含量高于对照组,而尿嘧啶、糖原等成分的含量低于对照组。结石组患者血浆中的甲基带含量高于对照组,而糖原、磷脂酰肌醇、蛋白质-酪氨酸、苯丙氨酸、棕榈酸/脂肪酸、羟脯氨酸/酪氨酸和脂类的含量低于对照组。结论采用SERS检测可发现肾结石患者的尿液和血液代谢成分与健康体检者存在差异,结合PCA-LDA与ROC分析法可能有助于肾结石患者的筛查。

表面增强拉曼光谱技术在新精神活性物质检测中的应用

表面增强拉曼光谱技术具有高灵敏的吸附增强效应,提供更强的拉曼信号,通过观察到的特有分子指纹信息可以对分析物做出鉴别.各类新精神活性物质均有相应的特征拉曼信号,因此将表面增强拉曼光谱技术应用于合成大麻素类、合成卡西酮类、哌嗪类、色胺类、氯胺酮及苯环利定类和芬太尼类等新精神活性物质检测中.方法具有灵敏度高、样品处理简单和检测快速的优点,可为鉴定新精神活性物质的结构类别提供科学依据.本文介绍近年来表面增强拉曼光谱技术在各类新精神活性物质检测中的应用进展,旨在为新精神活性物质的筛查提供参考.

化工行业土壤中多环芳烃污染特征与检测技术研究

本文综述了中国焦化工业的概况和焦化废弃土壤中多环芳烃(PAHs)的污染特征,总结了土壤中PAHs的主要检测技术和前处理方法,以及不同固体样品前处理方法的原理和优缺点。同时,还探讨了表面增强拉曼技术(SERS)在土壤PAHs检测中的应用前景。最后,文中提出了土壤PAHs检测与前处理技术在未来的发展方向。

表面增强拉曼光谱法同时检测果汁中的啶虫脒和福美双

目的:基于优化的金银合金纳米颗粒基底的表面增强拉曼光谱(surface-enhanced Raman spectroscopy,SERS)同时检测果汁中啶虫脒和福美双。方法:对不同质量浓度的啶虫脒和福美双标准溶液及其混合物采集拉曼光谱并进行峰位归属分析,选择苹果汁作为代表果汁样本,对不同质量浓度梯度的混合农药残留进行检测分析,利用两种农药的拉曼特征峰强度与农药残留质量浓度分别建立校正曲线。最后通过回收率实验评估此方法的准确性和精密度。结果:631 cm^(-1)处的拉曼特征峰作为啶虫脒的识别峰,1380 cm^(-1)处的拉曼峰作为福美双的识别峰,同时检测苹果汁中混合农药残留,得到啶虫脒和福美双的检测限分别为0.42231 mg/L和0.03556 mg/L,均低于国家规定的苹果中啶虫脒(0.8 mg/L)和福美双(5 mg/L)的农药残留限量。回收率实验显示苹果汁中福美双和啶虫脒的平均回收率分别为81.67%~101.25%和98.70%~119.36%,相对标准偏差范围分别为2.72%~7.68%和5.44%~15.15%。结论:利用SERS技术的峰尖锐、峰宽窄的特点,结合金银合金纳米颗粒基底可实现果汁中啶虫脒和福美双的同时定量检测。此方法可以进一步应用于其他多种污染物的现场同时快速检测。

一种基于表面增强拉曼光谱技术的环境水中啶虫脒现场快速检测试剂盒

啶虫脒(acetamiprid,AC)在环境中的蓄积可对生态系统和人体健康产生不利影响。本研究利用表面增强拉曼光谱(Surface-enhanced Raman spectroscopy,SERS)技术,构建了一种快速定性及定量检测环境水中啶虫脒的检测试剂盒。采用化学合成法制备了粒径为40~60 nm的纳米金溶胶作为SERS活性基底,以包覆铝箔的24孔板为反应平台,将一定量的聚沉盐负载到反应孔中诱导信号热点,并与便携式拉曼光谱仪集成为适用于现场检测的试剂盒。通过对聚沉盐负载量、聚沉时间等条件进行优化,在浓度为25~750 ng·mL^(-1)范围内,啶虫脒浓度与SERS信号强度呈现良好的线性关系,R2=0.988。试剂盒检出限低至15.56 ng·mL^(-1),平均加标回收率为90.04%~106.10%,在5 min内实现了环境水中啶虫脒的现场检测。与传统方法相比,该试剂盒便携、操作简单、快速、成本低廉、可同时进行多样本检测,为环境水体中啶虫脒的现场检测分析提供了新选择。

表面增强拉曼光谱在动物源性食品兽药残留检测的研究进展

动物性食品安全问题日益突出,愈演愈烈,有关问题食品的报道也受到了公众的广泛关注。一旦兽药在畜牧养殖过程中被过度使用或滥用,药物残留将给人类健康带来严重危害。常见的残留检测方法存在成本高、速度慢和效率低等缺点,通常需要专业人员操作,传统的理化方法已不能满足食品质量检测的需要,因此研发快速高效的兽药残留检测方法起着关键作用。近年来,表面增强拉曼光谱(SERS)技术在真伪鉴别、非法添加物检测和农兽药残留等诸多领域得到了广泛应用,并以其快速检测、无损等优势在食品检测领域有着更为广阔的发展前景。与其他检测方法不同的是,SERS通过信号放大和高灵敏度的指纹光谱,可以快速识别目标分析物,进行定性或半定量分析。本文主要介绍了拉曼光谱和SERS在动物源性食品中兽药残留检测中的研究和应用,重点介绍了SERS的优势、食品样品的前处理以及SERS结合其他技术检测多种兽药的相关研究,并提出了SERS在实际监测中面临的挑战。

离子液体中PMBA脱羧反应及界面水影响的电化学SERS研究

基于气-液界面自组装法和转移技术制备了负载Au纳米粒子单层膜的玻碳电极(Au MLF@GC),并将其用于离子液体-电化学体系界面过程现场的研究.以对巯基苯甲酸(PMBA)的表面等离激元共振(SPR)催化脱羧生成苯硫酚(TP)反应为探针,采用电化学-表面增强拉曼光谱(SERS)技术,通过电位阶跃法研究了其在离子液体体系中的反应动力学行为.结果表明,亲水性离子液体[BMIm]BF_(4)/Au MLF@GC的零电荷电位(pzc)为−0.95 V,PMBA脱羧反应仅在pzc以正区间发生;通过SERS谱峰强度变化以二级反应拟合获得该反应的速率常数,发现其反应速率常数的对数与阶跃后电位呈线性关系;随着体系外加水的含量(摩尔分数)由0增至0.001和0.003,阶跃后发生脱羧反应的起始电位负移,且同一阶跃电位下反应速率常数随着外加水量的增加而增大.