标记免疫双组分的SERS检测研究

以金膜为免疫检测的基底, 采用自组装技术(Self-assembled monolayer, SAM)将ω-巯基十六酸(16-MHA)修饰于金膜后与抗体结合成固相抗体, 在此基础上组装“固相抗体-待测抗原-标记免疫金溶胶”三明治复合体系. 采用不同标记分子苯硫酚(Thiophenol)和4,4'-联吡啶(4,4'-Bipyridine)分别标记不同的免疫金溶胶, 利用表面增强拉曼光谱(SERS)谱峰较窄且具有较强的分辨率及高灵敏度的特点, 通过对两种标记分子特征谱峰的判断识别所加入的两种抗原. 通过选择合适的标记分子和一定尺度的免疫溶胶, 标记免疫SERS检测的检测限可达到飞克级(1—100 fg/mL).     

表面增强拉曼光谱研究以4,4'-联吡啶为标记分子的免疫检测

通过表面增强拉曼光谱(SERS)研究了标记分子4,4'-联吡啶在金溶胶上的吸附行为, 并将其与山羊抗小鼠IgG结合, 获得SERS标记免疫金溶胶. 在固相基底上组装抗体, 两者组装得到固相抗体-抗原-标记抗体“三明治”结构. 在单组分和双组分体系中借助抗体上标记金纳米粒子所带的SERS信号达到免疫检测的目的.     

表面增强拉曼光谱研究以4,4''''-联吡啶为标记分子的免疫检测

通过表面增强拉曼光谱(SERS)研究了标记分子4,4'-联吡啶在金溶胶上的吸附行为,并将其与山羊抗小鼠IgG结合,获得SERS标记免疫金溶胶.在固相基底上组装抗体,两者组装得到固相抗体-抗原-标记抗体“三明治”结构.在单组分和双组分体系中借助抗体上标记金纳米粒子所带的SERS信号达到免疫检测的目的.     

巯基苯类为标记分子免疫检测的FT-SERS光谱研究

以对巯基苯甲酸、苯硫酚为标记分子，与金纳米粒子生成具有SERS信号的标记金溶胶．在一定条件下，标记金溶胶与抗体羊抗小鼠IgG形成SERS标记免疫金溶胶．用组装金纳米粒子的玻璃表面吸附抗体，通过对相应抗原小鼠IgG的识别，形成固相抗体/抗原对，再将SERS标记免疫金溶胶组装到固相抗体/抗原对上，形成“固相抗体-待测抗原-标记抗体(即标记免疫金溶胶)”夹心复合物，进而通过拉曼标记分子的SERS信号进行免疫检测．     

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.     

表面等离激元增强金属光致发光助力表面增强拉曼光谱获取表界面分子的本征化学信息

<正>表面增强拉曼光谱(SERS)因其具有单分子的检测灵敏度和特异的分子指纹信息,在表面科学和分析检测领域得到广泛关注~1。拉曼光谱研究中除了利用谱峰频率外,还利用不同谱峰间的相对强度,以获得吸附分子的吸附构象、分子与金属界面电荷转移、材料局域化学性质等多种重要物理化学信息。然而在SERS中,贵金属纳米结构的局域表面等离激元共振(LSPR)不仅增强了样品的拉曼信号的绝对强度,也改变了SERS谱图中不同谱峰的相对强度,即不同频率的拉曼信号受到的增强作用不同,从而导致用SERS峰的相对强度所获得的样品的物理化学信息变得不可靠。虽     

组蛋白乙酰化的耦合增强拉曼散射生物传感方法

提出了一种组蛋白乙酰化修饰检测的耦合增强拉曼散射生物传感新方法. 该方法以金纳米粒子为表面增强拉曼散射(SERS)基底, 表面修饰乙酰化组蛋白H3多肽为识别探针, 对甲氧基苯硫酚(4-MTP)为拉曼标记物, 制备了组蛋白乙酰化修饰检测的SERS纳米探针. 通过紫外可见吸收光谱与动态光散射分析, 证实了组蛋白乙酰化抗体可介导SERS纳米粒子发生可控组装与聚集, 使SERS纳米探针间发生局域电场共振耦合, 产生显著增强的SERS信号. 基于此, 通过待测抗原与SERS纳米探针对抗体的竞争性相互作用, 我们设计了组蛋白乙酰化修饰检测的竞争免疫SERS生物传感方法. 该法操作简便、快速、重现性好, 且裸眼即能进行可视化鉴定. 通过设计不同染料标记的SERS纳米探针, 该法有望实现多种组蛋白修饰的复合检测.     

基于表面增强拉曼光谱的重金属离子检测

以对巯基苯甲酸为拉曼标记和自组装修饰分子, 在光亮金基底上修饰后作为检测基底, 在金纳米粒子表面修饰后获得具有表面增强拉曼光谱信号的标记金溶胶. 修饰的基底及纳米离子通过重金属离子与羧基端的配位而发生相互作用, 最终形成“金属基底-对巯基苯甲酸/重金属离子/对巯基苯甲酸-金属纳米颗粒”的三明治结构. 采用扫描电镜表征纳米粒子的组装及以表面增强拉曼光谱检测表面标记分子的信号, 以此实现重金属离子的检测. 以强螯合剂EDTA溶液淋洗三明治结构, 使重金属离子与金属基底以及纳米颗粒上的羧基的配位作用断裂, 获得可再次利用的修饰金基底.     

金纳米粒子组装体系中偶联单分子层膜结构的SERS光谱表征与分析

通过分子自组装方法制备4,4′-二硫联吡啶(PySSPy)单分子膜修饰的金电极. 利用所形成的对巯基吡啶自组装单分子膜(SAMs)作为偶联层进行金纳米粒子有序膜的组装. 对该纳米粒子组装体系进行Raman光谱测定, 得到了具有良好信噪比的对巯基吡啶单分子膜的表面增强拉曼散射(SERS)光谱. 在此基础上, 进一步采用电化学现场SERS光谱技术研究了该纳米粒子组装体系的SERS光谱随电位变化的规律. 在该体系稳定的电位范围内表征对巯基吡啶单分子膜的特征谱峰1011与1093 cm^-1、1575与1610 cm^-1以及1206与1215 cm^-1这三对谱峰其强度随着所施加电位的改变呈现出明显的规律性. 分析表明, 偶联单分子层中吡啶环芳香性随着所施加电位的改变而有规律地变化是SERS光谱特征改变的内在原因.     

对氯硝基苯吸附在银纳米粒子上的偶联反应

表面增强拉曼光谱(SERS)具有极高的检测灵敏度, 通过检测吸附分子的SERS信号, 可以获得表面吸附分子的结构以及可能发生的反应. 在拉曼激发光源的辐射下, 在碱性溶液中, 银纳米粒子表面吸附的对氯硝基苯(PCNB)的SERS光谱与其固体的常规拉曼光谱相比, 出现异常SERS谱. 通过采用密度泛函理论(DFT)计算, 对PCNB以及可能的偶联产物p,p''-二氯偶氮苯(DCAB)进行理论分析以及谱峰归属, 发现这些异常峰来自其偶联产物DCAB的偶氮C－N＝N－C基团的基频振动.     

The adsorption behavior of p-hydroxybenzoic acid on a silver-coated filter paper by surface enhanced Raman scattering

On dried filter paper coated with silver nanoparticles, surface-enhanced Raman scattering (SERS) spectra of p-hydroxybenzoic acid (PHBA) were studied, and high-quality SERS spectra were obtained, indicating that the silver-coated filter paper is a highly SERS-active substrate. The analysis showed that the adsorption behavior of PHBA molecules on silver nanoparticles coated on filter paper was different from that in silver aqueous colloids. On the filter paper, it was found that the SERS spectra of PHBA changed with the proportion of PHBA molecules and silver nanoparticles, indicating that the adsorption behavior of PHBA molecules changed with the proportion. The probable reasons are given.     

Adsorption mechanisms of sulfathiazole on gold,silver and copper surfaces studied by SERS

Surface-enhanced Raman scattering (SERS) of sulfathiazole was studied in gold, silver and copper colloids as well as on a gold plate. SERS spectra of sulfathiazole in gold and silver colloids indicated chemisorption of molecules on the metal nanoparticles through the amide nitrogen, with the phenyl moiety orthogonally placed and the thiazole ring almost parallel positioned towards the metal surface. Although selectively enhanced phenyl bands pointed to a very similar position of the sulfathiazole molecules on the copper colloid, a chemical bonding was not implied. Unlike adsorption mechanisms and position of the molecules on the colloid metal surfaces, a sideway adsorption of sulfathiazole on the gold plate was proposed. Hereby, both, the amide nitrogen and the thiazole nitrogen were considered responsible for approaching of sulfathiazole to the gold enhancing surface.     

Immunoassay using probe-labelling immunogold nanoparticles with silver staining enhancement via surface-enhanced Raman scattering

This paper reports a novel immunoassay based on surface-enhanced Raman scattering (SERS) and immunogold labelling with silver staining enhancement. Immunoreactions between immunogold colloids modified by a Raman-active probe molecule (e.g., 4-mercaptobenzoic acid) and antigens, which were captured by antibody-assembled chips such as silicon or quartz, were detected via SERS signals of Raman-active probe molecule. All the self-assembled steps were subjected to the measurements of ultraviolet-visible (UV-vis) spectra to monitor the formation of a sandwich structure onto a substrate. The immunoassay was performed by a sandwich structure consisting of three layers. The first layer was composed of immobilized antibody molecules of mouse polyclonal antibody against Hepatitis B virus surface antigen (PAb) on a silicon or quartz substrate. The second layer was the complementary Hepatitis B virus surface antigen (Antigen) molecules captured by PAb on the substrate. The third layer was composed of the probe-labelling immunogold nanoparticles, which were modified by mouse monoclonal antibody against Hepatitis B virus surface antigen (MAb) and 4-mercaptobenzoic acid (MBA) as the Raman-active probe on the surface of gold colloids. After silver staining enhancement, the antigen is identified by a SERS spectrum of MBA. A working curve of the intensity of a SERS signal at 1585 cm(-1) due to the [small nu](8a) aromatic ring vibration of MBA versus the concentration of analyte (Antigen) was obtained and the non-optimized detection limit for the Hepatitis B virus surface antigen was found to be as low as 0.5 [micro sign]g mL(-1).     

Non-labeling multiplex surface enhanced Raman scattering (SERS) detection of volatile organic compounds (VOCs)

In this paper, we report multiplex SERS based VOCs detection with a leaning nano-pillar substrate. The VOCs analyte molecules adsorbed at the tips of the nano-pillars produced SERS signal due to the field enhancement occurring at the localized surface plasmon hot spots between adjacent leaning nano-pillars. In this experiment, detections of acetone and ethanol vapor at different concentrations were demonstrated. The detection limits were found to be 0.0017 ng and 0.0037 ng for ethanol and acetone vapor molecules respectively. Our approach is a non-labeling method such that it does not require the incorporation of any chemical sensing layer for the enrichment of gas molecules on sensor surface. The leaning nano-pillar substrate also showed highly reproducible SERS signal in cyclic VOCs detection, which can reduce the detection cost in practical applications. Further, multiplex SERS detection on different combination of acetone and ethanol vapor was also successfully demonstrated. The vibrational fingerprints of molecular structures provide specific Raman peaks for different VOCs contents. To the best of our knowledge, this is the first multiplex VOCs detection using SERS. We believe that this work may lead to a portable device for multiplex, specific and highly sensitive detection of complex VOCs samples that can find potential applications in exhaled breath analysis, hazardous gas analysis, homeland security and environmental monitoring.     

碘化银胶体上四苯基卟啉金属配合物的表面增强拉曼光谱研究

研究了四苯基卟啉金属配合物（MTPP,M=Ag,Mg,Cu,Pd）在AgI胶体上的表面增强拉曼光谱（SERS）。结果显示MgTPP与基底发生金属交换生成AgTPP,而在PdTPP和CuTPP上则未发现金属交换。除卟啉环的振动外,一些苯环振动带也被显著增强。在1400～1600cm-1范围,PdTPP和CuTPP的SERS与AgTPP有很大差别,可能反映了吸附分子在次甲基桥碳原子Cm附近立体构型的差异。     

Surface-enhanced Raman scattering of a series of n-hydroxybenzoic acids (n = P, M and O) on the silver nano-particles

Surface-enhanced Raman scattering (SERS) spectra of a series of n-hydroxybenzoic acids (n-HBA, n = P, M and O) adsorbed on the silver nano-particles were studied, respectively, in the silver colloidal solution and on the dried silver-coated filter paper. On the same substrate, the different molecules' SERS spectra were different, while on the different substrates the same molecules' SERS spectra were also different. Significant changes were found in the SERS spectra of PHBA molecules adsorbed on the two substrates, and the changes found in MHBA's spectra on two substrates were next to PHBA's, while almost no changes were found in the spectra of OHBA molecules. Moreover, it was found, on the filter paper, that the SERS spectra of the same molecules would change with the coverage density of the silver nano-particles. The analyses showed that the origins of these changes were the different adsorption behavior of molecules adsorbed on the silver nano-particles. Because in these three molecules the relative positions of the carboxyls and hydroxyls on the benzenes are different, the adsorption behaviors of these three molecules adsorbed on the silver surfaces are also different. The experimental results suggest that the surface characteristic of the substrate and the surface configuration of the adsorbate could exert a great influence on the adsorption behavior of the adsorbates on the substrates.     

SURFACE-ENHANCED RAMAN SPECTRA OF p-AMINOBENZOIC ACID ADSORBED ON Ag2CO3 COLLOIDS

It was observed that the p-aminobenzoic acid(PABA)molecules adsorbed on A92CO3colloids exhibited strong SERS effect,the enhancement factor is estimated at 10~7—10~8 The mechanismof SERS effect on PABA adsorbed on the colloids was discussed.     

Gold colloid-bienzyme conjugates for glucose detection utilizing surface-enhanced Raman scattering

It is difficult to detect glucose by surface-enhanced Raman spectroscopy (SERS) due to the small normal Raman cross-section and the weak adsorption of glucose molecules on the surface of noble metal. A simple and fast method is proposed in this paper for the detection of glucose based on SERS signal of the enzyme reaction product and the difficulties have been circumvented. Gold colloids modified by horseradish peroxidase and glucose oxidase (HRP/GOD-gold colloids) are added to the mixture of o-phenylenediamine and glucose, and the resulting solution is allowed to react at room temperature for 5 min. Azoaniline, an azo compound with strong Raman scattering, is generated and the Raman scattering of this reaction product is enhanced when adsorbed on gold colloids. The intensity of the SERS spectrum is used for assessment of glucose content. The dynamic signal range provided by this analytical system is 0.50-32 mM, which covers the normal clinical range for glucose in blood from 3.5 to 6.1 mM. The detection limit is about 0.46 mM. The interference effect of several proteins on glucose detection is also investigated and has shown to have no effect on the measurement of glucose by the described technique.