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.     

A new and selective and sensitive nanogold-labeled immunoresoance scattering spectral assay for trace prealbumin

A gold-labeled immunoresonance scattering spectral probe for trace prealbumin (PA) was prepared by using gold nanoparticles in size of 9.0 nm to label goat anti-human prealbumin polyclonal antibody. The immune reaction between the gold-labeled antibody and prealbumin took place in pH 7.6 Na₂HPO₄-NaH₂PO₄ buffer solution. In the presence of polyethylene glycol PEG-10000, the labeled gold nanoparticles were released and aggregated which brought the resonance scattering intensity (I_RS) at 580 nm to enhance greatly. The ΔI_RS is proportional to the prealbumin concentration in the range from 16.67 to 666.67 ng/mL, with a detection limit of 4.1 ng/mL. This simple, sensitive and selective assay was applied to determination of prealbumin in human plasma, with satisfactory results.     

Immobilised gold nanostars in a paper-based test system for surface-enhanced Raman spectroscopy

Paper-based SERS active substrates were prepared adsorbing spherical and star-shaped gold nanoparticles on a standard filter paper support. Besides the deposition conditions, morphological parameters of the particles were found to strongly affect the enhancer properties of the substrates. The developed substrate was tested regarding surface homogeneity as well as in the quantitative analysis of malachite green, – a well documented Raman reporter dye – and proved to be capable also to detect the oxidation products of apomorphine, a well-known drug molecule used in Parkinson's disease. This material is simple to prepare, easy to handle and dispose and as such it could be a perfect target for further development of a new family of mass-produced, cheap solid SERS substrates.     

Amperometric tape ion sensors for cadmium(II) ion analysis

This paper describes a novel tape platform ion sensing methodology specific to the detection of cadmium(II) ions in aqueous solution based on assisted ion transfer reactions across a polarized water | organic gel micro-interface. The tape ion sensors were constructed to incorporate the micro-water | polyvinylchloride-2-nitrophenylethyl ether (PVC-NPOE) gel interfaces referred to as ionodes. The sensors have overall thicknesses less than 300 μm, allowing their packaging in a disposable tape format. The detection methodology is based on the selective assisted transfer of the cadmium ion in aqueous phase by ETH 1062 present in the PVC-NPOE gel layer and was first investigated using cyclic voltammetry. Quantitative analysis of cadmium(II) ions in aqueous solution using the tape sensors was then conducted under stop-flow conditions. Detection limits as low as 20 ppb (178 nM) for Cd(II) ions in very small volumes as low as a single 20 μl droplet without any sample preconcentration was achieved in an analysis time of approximately 20 s, which could be easily employed for the direct measurement of Cd(II) ion levels in various field applications. The tape ion sensor can also be used in a flow-cell geometry to preconcentrate Cd(II) ions from aqueous samples and further improve the detection limit.     

Isothiouronium-based amphiphilic gold nanoparticles with a colorimetric response to hydrophobic anions in water: a new strategy for fluoride ion detection in the presence of a phenylboronic acid

Gold nanoparticles modified with isothiouronium-derived amphiphile units 1 were prepared by the reduction of with NaBH₄ in the presence of bis(5-(N-(2-(2-methoxyethoxy)ethyl)-N-methyl-S-isothiouronio)pentyl) disulfide 2. The obtained nanoparticles 1 showed a selective coloration for hydrophobic anions in water, possibly due to an anion exchange and subsequent aggregation. On the basis of this observation, the detection of F⁻ in water has been achieved using 3-nitrophenylboronic acid as a mediator at pH 5.5, thereby providing a new strategy for the design of a F⁻ sensory system.     

Colorimetric detection of fluoride ion in an aqueous solution using a thioglucose-capped gold nanoparticle

The thioglucose-capped gold nanoparticles have been prepared by the chemical reduction of HAuCl₄ using thioglucose as the reducing and capping agent, which displays selective colorimetric detection of fluoride ion in 10 mM HEPES buffer at physiological pH.     

基于Au/SiO2纳米粒子的结晶紫表面增强拉曼特性研究

采用自组装-化学镀法制备了以SiO2为核,Au为壳层的核壳结构纳米粒子(Au/SiO2),以生物染色剂结晶紫为探针分子,研究了Au/SiO2的表面增强拉曼散射(SERS)效应,并考察了Cl-对SERS增强效应的影响。实验表明,Cl-对SERS有明显的增强效果,这主要是由于Cl-的加入使得Au/SiO2发生团聚,产生大量"热点",从而使SERS增强效果进一步加强。以Au/SiO2(5×1010 mL-1)为活性基底,KCl(0.01 mol/L)为额外增强剂,在水溶液中实现了对结晶紫(CV)的痕量检出,最低检测浓度可达到5×10-10mol/L。     

Cu2O/Ag纳米复合物的表面增强拉曼光谱

用一种简单的化学还原方法制备了银纳米粒子包覆的氧化亚铜（Cu2O）纳米复合物。扫描电子显微镜显示Cu2O 为八面体型的纳米粒子,表面光滑,结构对称。包覆的Ag部分占据Cu2O粒子表面。通过比较Ag/Cu2O纳米复合物、Ag溶胶及Cu纳米粒子表面吸附的4-巯基吡啶（4-Mpy）分子表面增强拉曼光谱（SERS）发现,利用此方法得到了Cu2O粒子表面吸附分子的拉曼光谱。银纳米粒子所产生的电磁场增强又增强了吸附在Cu2O上的4-Mpy拉曼信号。这种方法为初步研究Cu2O表面吸附分子性质提供了依据,扩宽了SERS的使用范围,使SERS应用在纳米半导体材料上成为可能。     

复合纳米材料Cu2O@Au对水体中罗丹明B的检测应用研究

制备了多面体Cu2 O纳米粒子,利用Cu2 O的还原性,在其表面原位生成了不同密度的Au纳米粒子,制备了Au、Cu共同增强拉曼信号的复合纳米粒子Cu2 O@Au.利用透射电镜(TEM)、扫描电镜(SEM)、X射线衍射(XRD)等对制备的Cu2 O和Cu2 O@Au的形貌、粒径、表面性能等进行了表征.研究了Cu2 O表面金纳米粒子的分布密度对水样中目标检测物罗丹明B的拉曼增强效果.结果表明,氯金酸浓度在1 mmol/L时制备的Cu2 O@Au表面均匀覆盖一层金纳米粒子,其表面增强拉曼效果最为显著,对水样中罗丹明B检测范围为1×10-2~5×10-6 mol/L.研究了此探针在PBS(1×)和酸性水溶液(0.01 mol/L HCl)中的稳定性,并将其用于沂河水样中靶标的检测实验,结果表明,其稳定性较好.     

Highly sensitive and selective assay method for iodide ion determination based on gold nanoparticles conjugated with glycol chitosan

A sensitive colorimetric method for the determination of iodide ions was developed using gold nanoparticles (AuNPs) functionalised with glycol chitosan (GCS). The iodide ions were at the centre of the O–I^––O coordination structure, formed with the GCS-AuNPs, reducing their interparticle distance and inducing aggregation. Time-of-flight secondary ion mass spectrometry analyses showed that the bound iodide ions were coordinated to the oxygen atoms of the ethylene glycol in GCS, with this aggregation leading to a considerable variation in colour from light red to dark violet. Using this GCS-AuNP probe, the iodide ion concentration in environmental, biological and pharmaceutical samples could be determined by both the naked eye and UV-Vis spectroscopy. Additionally, the sensitivity of the detection was found to be markedly enhanced at pH 6, where a more pronounced colour change was observed. The absorption ratio A₇₀₀/A₅₂₁ of the functionalised AuNP solution correlated linearly with the iodide ion concentration within the range 0.0–10.0 mg/L, and the limits of detection in tap water, pond water, and bovine serum solution were 3.5, 3.6, and 3.4 μg/L, respectively. The present assay method can thus be utilised to rapidly measure the concentration of iodide ions in aqueous samples.     

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)被用于检测细菌芽孢中的一种重要的标志物吡啶2,6-二羧酸(DPA)。以聚乙烯吡咯烷酮(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的影响。结果表明:在强酸条件下,DPA在Au NPs/PVP/Au基底上的SERS信号能达到最大增强;当pH值大于DPA二级解离常数时,DPA的SERS特征逐渐减弱。在DPA中引入不同酸根盐时,后者会取代纳米金表面的柠檬酸根所占的部分位点,改变Au NPs-Au基底的SERS增强性能。3种酸根吸附性能不同,所以获得的光谱强度存在差异。     

金纳米粒子修饰的氨基硅胶整体柱的制备及超灵敏表面增强拉曼散射检测

采用溶胶-凝胶法结合超分子模板技术, 以四乙氧基硅烷(TEOS)和3-氨丙基三乙氧基硅烷(APTES)作为反应前体, 以十六烷基三甲基溴化铵(CTMAB)为超分子模板, 简单快速地制备了一种新型氨基硅胶整体柱, 通过氨基将金纳米粒子组装在整体柱材料孔表面并用于表面增强拉曼散射(SERS)光谱分析. 以对巯基苯胺(PATP)和结晶紫(CV)为拉曼探针, 考察了金纳米粒子修饰的氨基硅胶整体柱用作SERS活性基底的性能. 结果表明, 该整体柱基底具有良好的SERS增强效应, 可检测到的PATP和CV的最低浓度分别为10^-9和10^-11 mol/L. 与金溶胶SERS基底相比, 本文制备的整体柱基底的检测灵敏度显著提高, 并具有良好的信号均一性, 是一种具有现场痕量检测应用潜力的SERS活性基底.     

Au@SiO2核壳纳米粒子的制备及其表面增强拉曼光谱

采用柠檬酸钠还原氯金酸法制备金溶胶, 以正硅酸乙酯(TEOS)为硅源, 氨水作催化剂, 制备以金为核, 二氧化硅为壳的核壳纳米粒子. 金纳米粒子的粒径可以通过柠檬酸钠和氯金酸的比例控制, 通过调节TEOS的量和反应的时间可以控制二氧化硅壳层的厚度. 以苯硫酚为探针分子研究了核壳结构纳米粒子的表面增强拉曼散射(SERS)效应与二氧化硅壳层厚度之间的关系. 研究结果表明, 金内核电磁场增强效应随着二氧化硅壳层厚度的增加逐渐减弱, 且其衰减速度比具有相同尺度的双金属核壳结构纳米粒子的慢. 此外, 探针分子主要以物理作用吸附在二氧化硅的表面, 可通过洗涤方法将探针分子除去, 从而可使该复合结构基底用于循环SERS分析.     

A surface-enhanced Raman scattering method for detection of trace glutathione on the basis of immobilized silver nanoparticles and crystal violet probe

Unsatisfactory sensitivity and stability for molecules with low polarizability is still a problem limiting the practical applications of surface-enhanced Raman scattering (SERS) technique. By preparing immobilized silver nanoparticles (Fe₃O₄/Ag) through depositing silver on the surface of magnetite particles, a highly sensitive and selective SERS method for the detection of trace glutathione (GSH) was proposed on the basis of a system of Fe₃O₄/Ag nanoparticles and crystal violet (CV), in which the target GSH competed with the CV probe for the adsorption on the Fe₃O₄/Ag nanoparticles. Raman insensitive GSH replaced the highly Raman sensitive CV adsorbed on the surface of Fe₃O₄/Ag particles. This replacement led to a strong decrease of the CV SERS signal, which was used to determine the concentration of GSH. Under optimal conditions, a linear response was established between the intensity decrease of the CV SERS signal and the GSH concentration in the range of 50–700 nmol L⁻¹ with a detection limit of 40 nmol L⁻¹. The use of a Fe₃O₄/Ag substrate provided not only a great SERS enhancement but also a good stability, which guarantees the reproducibility of the proposed method. Its use for the determination of GSH in practical blood samples and cell extract yielded satisfactory results.     

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.     

Ultrasensitive detection of lead ion based on target induced assembly of DNAzyme modified gold nanoparticle and graphene oxide

In this paper, we report a novel colorimetric strategy for the detection of small molecules by using Pb²⁺ ion as an example. In this strategy, DNAzyme duplex modified gold nanoparticles (GNPs) are designed to be unable to interact with graphene oxide (GO). However, in the presence of Pb²⁺, the substrate strand of the DNAzyme is cleaved at its cleavage site, resulting in the disassembly of the DNAzyme duplex modified GNPs into three parts, i.e., the 3′- and 5′-fragments of substrate strand and the DNAzyme strand modified GNPs. By taking advantage of the efficient cross-linking effect of ssDNA-GNPs to GO, colorimetric sensor for the detection of the metal ion can be fabricated with a detection limit of 100 pM, which is much lower than the previous reports. This colorimetric method has also been used for the determination of Pb²⁺ in the tap water of the local city and the water from a reservoir with satisfactory results, so it may have potential applications in the future.     

基于光子晶体带边效应的表面增强拉曼基底

将光子晶体的带边效应与金纳米粒子的拉曼散射增强作用相结合,制备了一种新型光子晶体表面增强拉曼散射基底(PC-AuNPs),利用罗丹明B(RhB)作为报告分子,对所得基底性能进行检测.PC-AuNPs基底的制备包括3个步骤:在SiO2微球表面修饰氨基,再通过垂直沉降自组装得到蛋白石结构光子晶体(PC), 最后, 在光子晶体表面负载金纳米粒子(AuNPs).结果表明,光子晶体的带隙范围及AuNPs的负载量直接影响了PC-AuNPs基底的检测效果;以所得的PC-AuNPs基底测定RhB分子,其拉曼散射特征峰强度与浓度对数值呈现良好的线性关系,线性方程为I=1711lg[RhB(mol/L)]+15244,线性相关系数R2=0.9994,检出限为1×10-8 mol/L,表明此PC-AuNPs基底可用于目标物的定性及定量检测.本方法提高了传统拉曼散射光谱检测灵敏度,操作简单,具有良好的重现性,可为其它新型检测基底的制备提供.     

Controllable Silver Plating on Silica for Surface-enhanced Raman Scattering

We proposed a facile and rapid method for preparing silica-silver core-shell(SSCS) substrates to use Ag electroless plating on SiO2@Au-seed particles.UV-Vis-NIR absorption spectrometer and SEM were employed to monitor the reaction process of the formation of Ag on the surfaces of silica beads,and the optical resonance of the substrate could shift from visible to NIR region.It has been found that surface-enhanced Raman scattering(SERS) enhancement changes with the electroless plating time and the SSCS substr...     

Enhancement of Raman Scattering of 1,4-Benzenedithiol by CdS Nanoparticles Assembled on a Silver Surface

CAS nanoparticles were assembled on the smooth surface of a piece of silver by using 1,4-benzenedithiol as coupling molecules. The SEM and resonance Raman spectroscopic characterizations demonstrate that the nanosized structure of CdS was still preserved upon assembly, and a two-dimensional structure of CdS nanoparticles was formed on the substrate surface. The FT-Raman spectra indicate that 1,4-benzenedithiol was coupled between CAS nanoparticles and the silver surface with a tilted orientation. The Raman scattering of 1,4-benzenedithiol was substantially enhanced by the assembled CdS nanoparticles, probably due to the alteration of the polarizability of 1,4-benzenedithiol and the electromagnetic interaction between the dipoles of the CdS particle with its image in the metal substrate.     

Raman and infrared spectroscopic investigation of contact ion pair formation in aqueous cadmium sulfate solutions

Raman and IR data for aqueous CdSO₄ and (NH₄)₂SO₄ solutions have been recorded over broad concentration and temperature ranges. Whereas the v₁-SO ₄ ^2– band profile is symmetrical in (NH₄)₂SO₄ solutions, in CdSO₄ solutions a shoulder appears on the high frequency side which increases in intensity with increasing concentration and temperature. The molar scattering coefficient of the v₁-SO ₄ ^2– band is the same for all forms of sulfate in (NH₄)₂SO₄ and CdSO₄ solutions and is independent of temperature up to 99°C. The high frequency shoulder is attributed to the formation of a contact ion pair [Cd²⁺OSO ₃ ^2– ] (11 associate). Also the v₃-SO ₄ ^2– antisymmetric stretching mode shows a splitting in the CdSO₄ solution. Further spectroscopic evidence for contact ion pair formation is provided by IR spectroscopy. No higher associates or anionic complexes are required to interpret the spectroscopic data. The degree of association has been measured as a function of concentration and temperature. The thermodynamic association constant, K_A=0.15±0.05 kg-mol^–1 at 25°C is estimated from the Raman data by an extrapolation procedure by taking account of the activity coefficients. Values are reported for the activity coefficient of the ion pair. From the Raman temperature dependence studies, the enthalpy of formation for the contact ion pair is estimated to be 10±1 kJ-mol^–1.