固体活性基底表面增强拉曼光谱研究进展

表面增强拉曼光谱(SERS)是一种研究分子吸附和界面现象的有效手段,它促进了拉曼光谱技术应用的发展,其增强机理主要包括电磁增强机理和化学增强机理。固体活性基底是SERS技术的重要组成部分,综述了水体系和非水体系SERS固体活性基底的研究状况及SERS固相基底在定量分析方面的应用,指出了SERS固体活性基底在非水体系的应用潜力。     

一种新型表面增强拉曼活性基底的制备方法

表面增强拉曼光谱技术 (SERS)具有极高的灵敏度 ,对某些分子其灵敏度比常规拉曼光谱高一百万倍 ,能检测吸附在金属表面的单分子层和亚单分子层的分子 ,并提供丰富的分子结构信息 [1～ 5] .活性基底的制备是获得 SERS信号的前提 ,电化学粗糙化的电极、贵金属溶胶及真空蒸镀的金属岛膜是SERS分析中最常用的 3种活性基底 ,在实际应用中各有利弊 .本文报道一种新的制备银纳米粒子基底的方法 ,可使银纳米粒子生长到合适的尺寸 ,以达到最佳SERS增强效果 .利用紫外 -可见光谱和 AFM研究该 SERS基底纳米粒子的尺寸分布和形貌 ,以 1 ,4-(双…     

SnO2纳米粒子作为SERS基底的研究

采用溶胶-水热法制备了不同尺寸的SnO2纳米粒子, 并将其作为表面增强拉曼散射(Surface-enhanced Raman scattering, SERS)活性基底, 重点探讨了表面缺陷能级与SERS性能的关系. 观察到4-巯基苯甲酸(4-MBA)吸附在150 ℃水热合成的SnO2纳米粒子上的SERS 信号最强, 随着在空气中煅烧温度的升高, SERS信号逐渐减弱. 分别用透射电子显微镜、 紫外-可见光谱、 荧光光谱、 X射线衍射和X射线光电子能谱对SnO2纳米粒子进行了表征. 结果表明, SnO2纳米粒子的表面氧空位和缺陷等表面性质在增强拉曼散射性能中发挥着重要的作用, 表面氧空位和缺陷等含量越高其SERS信号就越强.     

基于银镜的高灵敏表面增强拉曼光谱基底制备及其用于呋喃唑酮检测

采用化学沉积法制备了表面增强拉曼散射光谱(SERS)银镜基底,用NaCl溶液与HCl溶液除去银镜表面杂质后,通过扫描电子显微镜对基底进行了表征,表明该基底表面的银纳米粒子平均粒径约为200 nm,以对巯基苯胺为探针分子测得其增强因子为4.6×105.利用表面增强拉曼光谱及表面吸附选择定律研究了广谱抗菌药呋喃唑酮在该基底表面的吸附状态,证明呋喃唑酮分子主要是通过CN吸附于银纳米粒子表面的.     

铑电极上的表面增强拉曼光谱研究(英文)

本文简要介绍了将铑电极用于表面增强拉曼光谱 (SERS)研究的方法 .具有较强活性的铑电极可以通过对电极施加方波电流进行恒电流粗糙获得 .对模型分子吡啶进行的表面拉曼光谱研究表明 ,该电极具有很好的稳定性和可逆性 ,并且其表面增强因子可达 4 0 0 0 .在对铑电极上一氧化碳的氧化过程进行的拉曼光谱研究中同时检测到桥式和线型吸附的C O和Pt C振动的拉曼信号 .本研究表明铑电极可作为多用的SERS基底 ,拉曼光谱可作为界面研究的通用工具 .     

应用于基因分析的最新SERS技术*

表面增强拉曼散射（SERS）是一种基于拉曼散射原理识别生物及化学分子的分析方法。SERS具有灵敏度高、水干扰小、分辨率高、稳定性好等优点,广泛应用于生物分析和生物医学研究领域。近年来,SERS技术在基因分析领域得到迅速的发展,成为国内外研究的热点。本文对应用于基因分析的一些最新SERS技术（包括基因的免标记检测和标记检测）进行较为全面的综述,着重介绍了免标记检测中基于金属纳米粒子和针尖增强拉曼散射的SERS技术,标记检测中基于拉曼活性物、PCR技术、分子信标、基底和标记物的SERS信号放大技术,并概括了基因多组分检测技术及SERS技术的应用前景。     

pH值和阴离子对吡啶2,6-二羧酸在金纳米颗粒表面的增强拉曼散射的影响

表面增强拉曼散射(SERS)被用于检测细菌芽抱中的一种重要的标志物吡啶2,6-羧酸(DPA).以聚乙烯吡啶烷酮(PVP)为粘合剂,将60 nm的金粒子组装到表面打磨光滑的金电极上,制备稳定、灵敏的SERS基底.通过不同pH值下吸附在金基底上的DPA的SERS特征,考察DPA分子吸附构型发生的变化,并分析酸根离子对其吸附...     

碳纳米管@SiO_2@Ag纳米复合材料的制备及其表面增强拉曼效应

本文以SiO2为中间层,在多壁碳纳米管(MWCNTs)表面负载Ag纳米粒子,制备出CNTs@SiO2@Ag纳米复合材料,并采用TEM、XRD、UV-Vis、XPS等对纳米复合材料的结构、形貌和成分进行了表征,同时对该纳米复合材料的表面增强拉曼散射(Surface-enhanced Raman scattering,SERS)效应进行了研究。结果显示,Ag纳米颗粒有效提高了CNTs的SERS活性,纳米复合材料的拉曼峰强度是单纯CNTs拉曼峰强的近5倍。进一步研究了吸附罗丹明6G生物染料分子的SERS光谱,结果表明R6G分子的拉曼信号的质量与强度得到显著提高。因此,所制备的CNTs@SiO2@Ag纳米复合材料有望作为SERS的活性基底,应用于生物无损检测领域。     

利用去湿现象制备具有SERS活性的银纳米粒子图案

构建了具有表面增强拉曼散射(SERS)活性的二维有序环状与盘状的银纳米粒子结构, 利用CTAB包覆银纳米粒子的氯仿溶液直接在图案化的金基底上进行去湿, 当改变银纳米粒子的浓度时可以得到不同的图案. 利用原子力显微镜(AFM)对其结构进行了表征, 以4-巯基吡啶作为探针分子, 采用表面增强拉曼成像技术研究了这种基底的SERS活性, 这将为SERS的研究开拓新的领域.     

SERS标记的金纳米棒探针用于免疫检测

报道了基于金纳米棒表面增强拉曼散射(SERS)的免疫检测. 将拉曼活性分子对巯基苯甲酸吸附于金纳米棒表面, 制备出SERS标记的金纳米棒探针. 该探针和蛋白抗体结合形成SERS标记抗体. 通过SERS标记抗体、待测抗原和俘获抗体(固体基底上修饰的抗体, 即俘获抗体)之间的免疫应答反应, 将金纳米棒探针组装到固体基底上, 形成SERS标记抗体-抗原-俘获抗体 “三明治”夹心复合体. 待测抗原浓度越大, 固体基底上俘获的金纳米棒探针的数目越多, 从而可通过SERS信号的强弱来检测待测抗原的浓度. 由于金纳米棒的表面等离子体共振(SPR)峰位置可以在较宽的范围内调控, 可通过激发光和SPR的耦合来提高SERS信号, 从而提高免疫检测的灵敏度. 单组分抗原可检出的浓度范围高于1×10－8 mg/mL.     

Frequency Shift in Graphene‐Enhanced Raman Signal of Molecules

Graphene‐enhanced Raman scattering (GERS) is emerging as an important method due to the need for highly reproducible, quantifiable, and biocompatible active substrates. As a result of its unique two‐dimensional carbon structure, graphene provides particularly large enhanced Raman signals for molecules adsorbed on its surface. In this work, the GERS signals of a test molecule, 4‐mercaptobenzoic acid (4‐MBA), with reproducible enhancement factors are discussed and compared with surface‐enhanced Raman scattering (SERS) signals from highly active substrates, covered with spherical silver nanoparticles. It is shown that chemical interactions between the molecule and graphene can result in a frequency shift in the graphene‐enhanced Raman signal of the molecule.     

吡啶在几种金属纳米线阵列上的表面增强喇曼光谱

近20多年来利用表面增强喇曼光谱（SERS）的研究还仅限于Ag,Au,Cu这三种具有强SERS效应的金属,最近,田中群等利用合适的表面处理方法和共焦曼光谱技术成功地获得了许多无机离子和有机小分子吸附在一系列的过渡金属（如Pt,Ni,Fe,Pd,Rh,Co,Ru等）上的SERS光谱,拓宽了SERS的应用范围,但这些表面处理方法对基底进行处理时存在着较大的随机性,从而导致对所得SERS信号的解释困难。近年来通过自组装膜、模板合成等技术可得比较有序具有强SERS效应的或表面,例如Nie等最近发现尺寸分布狭窄的Ag溶胶粒子（约80－100nm）能诱导出巨大的SERS增强;Freeman和C tffumj m jf rbutb uqf At A 体微粒组装在聚合物基底上,制得高活性的SERS基底,以上工作都表明制备有序纳米级金属颗粒表面将推动SERS的应用和机理研究,迄今,3半导体纳米线阵列上的喇曼光谱已有报道,而利用金属纳米线阵列作为SERS基底除半于样模合成法制备的Ag纳米线阵列上的SERS之外,尚未见其它相关报道,本文主要研究样模合成法制备金属纳米线的过程,并以此为基底研究吡啶吸附的SERS光谱。     

Silver Nano Islands Enhanced Raman Scattering on Large Area Grating Substrates Fabricated by Two Beam Laser Interference

The authors preparedlarge area surface-enhanced Raman scattering(SERS) active substrates with tunable enhancement. First the large area gratings were fabricated by scanning a photoresist with two-beam laser interference and subsequently they were coated with silver nano islands via vacuum evaporation. SERS active metal island grating substrates with four different periods(300, 400, 515 and 600 nm) and Ag nano islands uniformly coated on an area of 2.5 cm×0.5 cm were obtained. The measured SERS spectra reveal the tuning effect of the period on the Raman signals period. The highest enhancement(ca. 10⁵) for Rhodamine 6G(R6G) as probing molecule is associated with a period of 515 nm due to the perfect matching of surface plasmons and Raman excitation line. A good reproducibility of SERS signals with almost the same SERS intensity at different spots was observed on all the larger area Ag island grating substrates.     

Surface-enhanced Raman spectroscopy: substrate-related issues

After over 30 years of development, surface-enhanced Raman spectroscopy (SERS) is now facing a very important stage in its history. The explosive development of nanoscience and nanotechnology has assisted the rapid development of SERS, especially during the last 5 years. Further development of surface-enhanced Raman spectroscopy is mainly limited by the reproducible preparation of clean and highly surface enhanced Raman scattering (SERS) active substrates. This review deals with some substrate-related issues. Various methods will be introduced for preparing SERS substrates of Ag and Au for analytical purposes, from SERS substrates prepared by electrochemical or vacuum methods, to well-dispersed Au or Ag nanoparticle sols, to nanoparticle thin film substrates, and finally to ordered nanostructured substrates. Emphasis is placed on the analysis of the advantages and weaknesses of different methods in preparing SERS substrates. Closely related to the application of SERS in the analysis of trace sample and unknown systems, the existing cleaning methods for SERS substrates are analyzed and a combined chemical adsorption and electrochemical oxidation method is proposed to eliminate the interference of contaminants. A defocusing method is proposed to deal with the laser-induced sample decomposition problem frequently met in SERS measurement to obtain strong signals. The existing methods to estimate the surface enhancement factor, a criterion to characterize the SERS activity of a substrate, are analyzed and some guidelines are proposed to obtain the correct enhancement factor.     

Microspectrometric investigation of active substrates for surface enhanced Raman scattering

The results of investigations of several new active silver substrates and some previously reported active silver substrates for surface enhanced Raman spectrometry (SERS) using a Raman microprobe are given. Filter-papers of different composition and porosity, silver membranes and glass slides are evaluated as supports for SERS active substrates. Methods of silver preparation include evaporation and chemical reduction. The Raman microprobe facilitates the acquisition of SER spectra of the adsorbate over the metal microstructure being observed on a TV monitor. This capability allows the establishment of practical relationships between the surface morphology and SERS activity which can be used as guidelines for SERS experiments with the microprobe. For the most monodisperse substrates, it is possible to establish a linear relationship between SERS intensity and adsorbate concentration. In the lower extreme of the calibration graph, the amount of adsorbate being observed under the microscope objective is only 0.3 amol or 1.9 × 10⁵ molecules.     

Characterization of the surface enhanced raman scattering (SERS) of bacteria

The surface enhanced Raman scattering (SERS) of a number of species and strains of bacteria obtained on novel gold nanoparticle (approximately 80 nm) covered SiO(2) substrates excited at 785 nm is reported. Raman cross-section enhancements of >10(4) per bacterium are found for both Gram-positive and Gram-negative bacteria on these SERS active substrates. The SERS spectra of bacteria are spectrally less congested and exhibit greater species differentiation than their corresponding non-SERS (bulk) Raman spectra at this excitation wavelength. Fluorescence observed in the bulk Raman emission of Bacillus species is not apparent in the corresponding SERS spectra. Despite the field enhancement effects arising from the nanostructured metal surface, this fluorescence component appears "quenched" due to an energy transfer process which does not diminish the Raman emission. The surface enhancement effect allows the observation of Raman spectra of single bacterial cells excited at low incident powers and short data acquisition times. SERS spectra of B. anthracis Sterne illustrate this single cell level capability. Comparison with previous SERS studies reveals how the SERS vibrational signatures are strongly dependent on the morphology and nature of the SERS active substrates. The potential of SERS for detection and identification of bacterial pathogens with species and strain specificity on these gold particle covered glassy substrates is demonstrated by these results.     

Chemical Enhancement and Quenching in Single-Molecule Tip-Enhanced Raman Spectroscopy

Despite intensive research in surface enhanced Raman spectroscopy (SERS), the influence mechanism of chemical effects on Raman signals remains elusive. Here, we investigate such chemical effects through tip-enhanced Raman spectroscopy (TERS) of a single planar ZnPc molecule with varying but controlled contact environments. TERS signals are found dramatically enhanced upon making a tip–molecule point contact. A combined physico-chemical mechanism is proposed to explain such an enhancement via the generation of a ground-state charge-transfer induced vertical Raman polarizability that is further enhanced by the strong vertical plasmonic field in the nanocavity. In contrast, TERS signals from ZnPc chemisorbed flatly on substrates are found strongly quenched, which is rationalized by the Raman polarizability screening effect induced by interfacial dynamic charge transfer. Our results provide deep insights into the understanding of the chemical effects in TERS/SERS enhancement and quenching.     

有序表面增强拉曼散射基底制备的研究发展北大核心CSCD

表面增强拉曼散射(Surface Enhanced Raman Scattering,SERS)是一种振动光谱技术,可直接识别目标分析物。在分析应用中,SERS信号的重现性极其重要,而这在很大程度上取决于SERS基底结构的均匀性。目前,SERS基底的重现性一直是制约该技术在分析测试中广泛应用的瓶颈,规则排列的纳米结构构成的有序化SERS基底的可控制备是该领域发展的前沿和趋势。本文就SERS基底的有序化制备方法及其应用进行了总结,分析了自组装法、光刻技术和模板辅助法所制备的有序SERS基底的特征、有序性形成原理和在分析测试中应用的可行性,为拓展SERS的实际应用提供一定的参考。     

Droplet formation via flow-through microdevices in Raman and surface enhanced Raman spectroscopy--concepts and applications

This review outlines concepts and applications of droplet formation via flow-through microdevices in Raman and surface enhanced Raman spectroscopy (SERS) as well as the advantages of the approach. Even though the droplet-based flow-through technique is utilized in various fields, the review focuses on implementing droplet-based fluidic systems in Raman and SERS as these highly specific detection methods are of major interest in the field of analytics. With the combination of Raman or SERS with droplet-based fluidics, it is expected to achieve novel opportunities for analytics. Besides the approach of using droplet-based microfluidic devices as a detection platform, the unique properties of flow-through systems for the formation of droplets are capitalized to produce SERS active substrates and to accomplish uniform sample preparation. Within this contribution, previous reported applications on droplet-based flow-through Raman and SERS approaches and the additional benefit with regard to the importance in the field of analytics are considered.