虚拟分子印迹与表面增强拉曼散射联用技术用于孔雀石绿的超灵敏检测

采用抗坏血酸还原法制备Ag球粒子,然后用3-（甲基丙烯酰氧）丙基三甲氧基硅烷使其表面硅烷化,最后用虚拟模板分子松香酸代替模板分子孔雀石绿与功能单体甲基丙烯酰胺反应合成虚拟印迹聚合物.结果表明,生成的"核-壳"式复合基底比Ag的表面增强拉曼散射（SERS）增强效果显著,其对孔雀石绿的最低检测浓度达到10^-11 mol/L.该方法实现了背景噪音的消除,提高了分析结果的准确性,为有机染料的超灵敏检测提供了参考.     

纳米金/银修饰的空心/杂化微球的制备及其作为综合性能优异的三维拉曼增强基底的研究

以带正电的聚苯乙烯(PS)微球为模板分别制备出表面层为二氧化硅的杂化微球(PS@Si O2)及空心二氧化硅微球(HSSi,hollow spheres of Si O2).利用巯基硅烷偶联剂的桥联作用将金或银纳米粒子修饰到二氧化硅壳层的外表面,制备出4种结构均匀、体积窄分布的复合粒子:(1)纳米金修饰在空心二氧化硅微球的外表面(HSSi-Au NPs);(2)纳米金修饰在实心的PS/二氧化硅杂化微球(PS为核、二氧化硅为壳层)的外表面(PS@Si O2-Au NPs);(3)纳米银修饰在空心二氧化硅微球的外表面(HSSi-Ag NPs)以及(4)纳米银修饰在实心的PS/二氧化硅杂化微球的外表面(PS@Si O2-Ag NPs).分别利用上述4种复合粒子作为拉曼增强(SERS)基底,并以结晶紫(CV)为探针分子对各基底的拉曼增强效果进行了研究,其CV检测限依次为10-10、10-9、10-11和10-11mol/L,均具有较高的灵敏度.结果表明,以空心二氧化硅微球作为载体的增强效果优于以实心的杂化微球作为载体的增强效果(HSSi-Au NPs对CV的检测限比PS@Si O2-Au NPs对CV的检测限低1个数量级;虽然HSSi-Ag NPs和PS@Si O2-Ag NPs对CV的检测限相同,但对于相同浓度的CV,前者所获得的信号要明显强于后者).多次随机的重复测试表明,上述4种基底均具有优良的重复性.将上述4种基底在实验室放置3个月后用于CV的检测,各个基底仍具有相近的拉曼增强效果,即上述4种SERS基底的稳定性良好.     

Ag/mSiO2空心微球的制备及SERS标记性能

以聚苯乙烯微球为模板, 经过原位还原和种子生长过程在聚苯乙烯微球表面包覆银(Ag)纳米粒子; 以正硅酸乙酯为硅源, 在十六烷基三甲基溴化铵的导向下实现介孔二氧化硅(mSiO₂)可控包覆, 去除模板得到Ag/mSiO₂空心微球. 透射电子显微镜(TEM)和氮气吸附-脱附分析结果表明, SiO₂壳层厚度约为20 nm, 介孔孔径为2.1 nm, 孔道分布均匀. 进一步利用虹吸作用使对巯基苯胺(4-ATP)分子进入微球内与Ag粒子结合, 构建表面增强拉曼散射(SERS)标记材料. SERS测试结果表明, 该标记材料检测限达到10^-7 mol/L, SERS增强因子达到3.7×10⁵.     

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。     

Au/Ag复合纳米笼在表面增强拉曼光谱中的应用

表面增强拉曼光谱（SERS）技术是一种基于贵金属纳米结构基底对被检测物进行高灵敏度检测的一种方法.具有特殊纳米结构的贵金属表面受到激光的照射时，金属表面的自由电子会受到极大的振荡，当入射光频率与振荡频率相近时，则会发生表面等离子体共振现象（SPR），使金属表面的局域电场强度极大增强，入射光强度和散射光强度都得到成倍的放大，从而使吸附在贵金属纳米结构表面的分子的拉曼散射信号得到有效的增强.使用NaBH₄还原-酸刻蚀模板法，制备了八面体Au/Ag复合纳米笼，其形貌规整，尺寸均匀约为600 nm，无Cu₂O模板的残留，Au元素均匀负载在Ag纳米笼上，质量分数约为16.8%；Au/Ag复合纳米笼的紫外可见吸收峰相对于Ag纳米笼发生了红移，更重要的是，Au和Ag元素协同赋予了复合纳米笼超高的SERS灵敏度和重复性，Au/Ag复合纳米笼实现了对罗丹明6G的痕量检测（5×10^-14 mol/L），通过时域有限差分法（FDTD）模拟证实：这主要归因于等离子共振作用产生的高电磁场强度；此外，Au元素的加入使Au/Ag复合纳米笼具有优异的抗氧化性和化学稳定性，即使在1%的H₂O₂溶液中浸泡3 h，仍然能够保持优异的SERS性能.八面体Au/Ag复合纳米笼有望成为一种具有应用前景的高灵敏度、高稳定性的SERS基底.     

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。     

Au@PVP核壳纳米粒子作为表面增强拉曼散射基底检测孔雀石绿

采用水热法合成了粒径均一、壳层厚度可控的Au@PVP核壳纳米粒子,利用壳层PVP分子分散纳米粒子的特性,使其形成均一、排列致密的单层结构,利用其内核金纳米粒子的等离子共振效应实现了孔雀石绿( MG)分子的表面增强拉曼检测。通过优化吸附时间与壳层厚度,在致密的、均匀的核壳纳米粒子表面增强拉曼散射(SERS)基底上实现MG分子高灵敏分析检测,检测线性范围1×10-10~1×10-5 mol/L,线性相关系数R2达到0.98,检出限可达1×10-12 mol/L。将本方法用于罗非鱼鱼肉中MG含量检测,样品未检出,样品加标回收率为70.8％~126.0％。结果表明,本方法快速准确、操作简单,可用于鱼肉中MG的快速检测。     

表面增强拉曼散射纳米针尖用于单细胞内环境的检测研究

表面增强拉曼散射（SERS）纳米针尖是一类单细胞分析新技术,在细胞内环境检测和细胞生理功能研究等方面具有良好的应用潜力。由于SERS纳米针尖可负载的贵金属粒子数量少,因此,筛选和修饰高SERS增强能力的纳米粒子是确保其检测灵敏度的关键。本研究制备了一种核-卫星结构的Au纳米粒子,单颗粒信号较传统Au纳米球和Au纳米星显著提高。将此粒子涂覆在尖端直径约为200 nm的玻璃毛细管表面,形成SERS纳米针尖,进一步功能化修饰靶标敏感型拉曼报告分子,使其具备检测微区环境中p H值和O2的能力。作为应用性能考察,采用SERS纳米针尖实现了单个HL-7702细胞内pH值和缺氧状态监测。本研究解决了传统颗粒态SERS探针用于细胞分析面临的随机聚集和难以精确定位等瓶颈问题,为单细胞内环境检测分析提供了一种新的分析工具。     

Au@TiO2核壳纳米粒子光催化过程的表面增强拉曼光谱研究

利用聚电解质的静电吸附作用（层层组装）,在Au纳米粒子表面包裹上不同层数的二氧化钛前驱体TALH,通过退火形成Au@TiO2复合纳米粒子.以苯硫酚（TP）作为探针分子对退火前复合纳米粒子不同壳层厚度的SERS效应进行表征;可以发现：SERS信号强度的变化跟壳层厚度密切相关,当Au表面包裹至三层TALH时,信号几乎完全消失.此外,结合紫外照射,利用SERS对亚甲基蓝在TiO2壳层表面的光催化降解过程进行现场研究.结果表明：MB的降解主要经历了从多体及二聚体吸附逐渐向单体吸附方式转变,随后又经历了一个脱甲基的过程.因此,本工作发展了将一种紫外催化与现场SERS检测相结合的技术,该技术有望发展成为检测光催化过程,研究表面催化机理的一种强有力的工具     

Ag/Si-NPA基底上共吸附R6G和CV的表面增强拉曼散射

以硅纳米孔柱阵列(Si-NPA)为基底, 采用浸渍沉积技术制备了具有较高表面增强拉曼散射(SERS)活性的Ag/Si-NPA衬底, 并采用扫描电子显微镜和透射电子显微镜对其表面形貌和结构进行了表征. 在此基础上, 选择罗丹明6G(R6G)和结晶紫(CV)2种生物染料分子并采用不同的混合吸附程序对其共吸附状态下的SERS光谱进行了探测. 结果表明, 当2种分子的溶液浓度均为10^-7 mol/L时, 无论采用何种浸渍吸附程序, 其SERS谱中CV的特征拉曼峰都被R6G完全掩盖. 对溶液采用错级配置(R6G和CV的浓度分别为10^-9和10^-7 mol/L)后, 所测SERS谱上获得了分别对应于R6G和CV的分离良好、相对强度匹配、分辨率高的2个SERS特征峰组, 从而有利于简化现实混合探测过程中对SERS特征峰的指认和判断.     

Multifunctional Fe3O4@mTiO2@noble metal composite NPs as ultrasensitive SERS substrates for trace detection

Multifunctional materials have become the development trend of current material preparation. We reported a typical layer-by-layer method for the fabrication of multifunctional Fe₃O₄@mTiO₂@noble metal triplex core-shell composite nanoparticle (NP), which is composed of a magnetic Fe₃O₄ particle as the core, a mesoporous TiO₂ interlayer and a layer of Ag nanoparticles or Au nanorods as the shell. The obtained Fe₃O₄@mTiO₂@noble metal composite NPs have shown excellent surface enhanced Raman scattering (SERS) sensitivity. Raman results present that the limit of detection (LOD) for crystal violet (CV), p-aminothiophnol (p-ATP) and p-mercaptobenzoic acid (p-MBA) of the Fe₃O₄@mTiO₂@noble metal composite NPs substrates are as low as 1.0 × 10⁻⁹ M, 1.0 × 10⁻¹² M and 1.0 × 10⁻⁹ M, respectively. In addition, the composite NPs also show high reproducibility and stability across the entire area with relative standard deviations (RSD) less than 15.00%. These highly sensitivity with good reproducibility can be attributed to the presence of plentiful “hot spots” produced by magnetic aggregation and target molecules enrichment by mesoporous TiO₂ adsorption for practical application. Fe₃O₄@mTiO₂@Ag composite NPs were used for thiram detection and the detection limit can reach to 5.0 × 10⁻⁸ M (about 0.012 ppm), which is lower than the maximal residue limit of 7 ppm in fruit prescribed by the U.S. Environmental Protection Agency. These multifunctional composite NPs provide easy separation, enrichment and trace detection of the analyte, exhibiting a great prospect as a potential SERS sensor in complex environments.     

Silver Molecularly Imprinting Polymer for the Determination of p-Nitroaniline by Surface Enhanced Raman Scattering

Molecular imprinting and surface enhanced Raman scattering (SERS) were used to prepare a core-shell Ag@molecularly imprinting polymer (MIP) for the determination of p-nitroaniline. The obtained Ag@MIP exhibits a detection limit of 10^?12 M, which demonstrates higher sensitivity toward p-nitroaniline than conventional approaches. In addition, the Ag@MIP shows good recyclability, and simultaneously offers better stability and high SERS activity for recognizing target molecules. To characterize the high SERS activity of the SERS-MIP hybrid material, a possible mechanism for the SERS substrate is proposed involving enhancement by the MIP. This study is expected to provide an alternative approach for the determination of p-nitroaniline in aqueous environments.     

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.     

Fabrication and Formation Mechanism of Ag Nanoplate‐Decorated Nanofiber Mats and Their Application in SERS

We report a new simple method to fabricate a highly active SERS substrate consisting of poly‐m‐phenylenediamine/polyacrylonitrile (PmPD/PAN) decorated with Ag nanoplates. The formation mechanism of Ag nanoplates is investigated. The synthetic process of the Ag nanoplate‐decorated PmPD/PAN (Ag nanoplates@PmPD/PAN) nanofiber mats consists of the assembly of Ag nanoparticles on the surface of PmPD/PAN nanofibers as crystal nuclei followed by in situ growth of Ag nanoparticles exclusively into nanoplates. Both the reducibility of the polymer and the concentration of AgNO₃ are found to play important roles in the formation and the density of Ag nanoplates. The optimized Ag nanoplates@PmPD/PAN nanofiber mats exhibit excellent activity and reproducibility in surface‐enhanced Raman scattering (SERS) detection of 4‐mercaptobenzoic acid (4‐MBA) with a detection limit of 10^?10 m , making the Ag nanoplates@PmPD/PAN nanofiber mats a promising substrate for SERS detection of chemical molecules. In addition, this work also provides a design and fabrication process for a 3D SERS substrate made of a reducible polymer with noble metals.     

Surface-enhanced Raman spectroscopic detection of Bacillus subtilis spores using gold nanoparticle based substrates

The detection of bacterial spores requires the capability of highly sensitive and biocompatible probes. This report describes the findings of an investigation of surface-enhanced Raman spectroscopic (SERS) detection of Bacillus subtilis spores using gold-nanoparticle (Au NP) based substrates as the spectroscopic probe. The SERS substrates are shown to be highly sensitive for the detection of B. subtilis spores, which release calcium dipicolinate (CaDPA) as a biomarker. The SERS bands of CaDPA released from the spores by extraction using nitric acid provide the diagnostic signal for the detection, exhibiting a limit of detection (LOD) of 1.5×10(9) spores L(-1) (or 2.5×10(-14) M). The LOD for the Au NP based substrates is quite comparable with that reported for Ag nanoparticle based substrates for the detection of spores, though the surface adsorption equilibrium constant is found to be smaller by a factor of 1-2 orders of magnitude than the Ag nanoparticle based substrates. The results have also revealed the viability of SERS detection of CaDPA released from the spores under ambient conditions without extraction using any reagents, showing a significant reduction of the diagnostic peak width for the detection. These findings have demonstrated the viability of Au NP based SERS substrates for direct use with high resolution and sensitivity as a biocompatible probe for the detection of bacterial spores.     

Cetylpyridinium Chloride Activated Trinitrotoluene Explosive Lights Up Robust and Ultrahigh Surface‐Enhanced Resonance Raman Scattering in a Silver Sol

Surface‐enhanced resonance Raman scattering (SERRS) is not realized for most molecules of interest. Here, we developed a new SERRS platform for the fast and sensitive detection of 2,4,6‐trinitrotoluene (TNT), a molecule with low Raman cross section. A cationic surfactant, cetylpyridinium chloride (CPC) was modified on the surface of silver sols (CP‐capped Ag). CPC not only acts as the surface‐seeking species to trap sulfite‐sulfonated TNT, but also undergoes complexation with it, resulting in the presence of two charge‐transfer bands at 467 and 530 nm, respectively. This chromophore absorbs the visible light that matches with the incident laser and plasmon resonance of Ag sols by the use of a 532.06 nm laser, and offered large resonance Raman enhancement. This SERRS platform evidenced a fast and accurate detection of TNT with a detection limit of 5×10^?11 M under a low laser power (200 μW) and a short integration time (3 s). The CP‐capped Ag also provides remarkable sensitivity and reliable repeatability. This study provides a facile and reliable method for TNT detection and a viable idea for the SERS detection of various non‐resonant molecules.     

Synthesis of p-aminothiophenol-embedded gold/silver core-shell nanostructures as novel SERS tags for biosensing applications

We describe a novel surface-enhanced Raman scattering (SERS) tag that is based on Au/Ag core-shell nanostructures embedded with p-aminothiophenol. The Au/Ag core-shell sandwich nanostructures demonstrate bright and dark stripe structure and possess very strong SERS activity. Under optimum conditions, the maximum SERS signal was obtained with a 10?nm thick Ag nanoshell, and the enhancement factor is 3.4?×?10⁴ at 1077?cm^?1. After conjugation to the antibody of muramidase releasing protein (MRP), the Au/Ag core-shell nanostructures were successfully applied to an SERS-based detection scheme for MRP based on a sandwich type of immunoassay.

The ultratrace detection of crystal violet using surface enhanced Raman scattering on colloidal Ag nanoparticles prepared by electrolysis

Highly active,stable and affordable surface enhanced Raman scattering(SERS) substrates were obtained by electrolyzing a mixture of AgNO_3(4×10~(-4) mol/L) and Na_3C_6H_5O_7·H_2O(6×10~(-5) mol/L) for 1,2,3 and 4h at 7V.With crystal violet(CV) as a test molecule,a portable Raman spectrometer with 785 nm laser excitation was employed to carry out the SERS detection.Colloidal Ag nanoparticles prepared by electrolyzing for 3 h with the particle size of(65±17) nm is a perfect SERS substrate for the ultratrace ...     

Silver nanocubes monolayers as a SERS substrate for quantitative analysis

Surface-enhanced Raman scattering (SERS) is a powerful spectroscopic tool in quantitative analysis of molecules, where the substrate plays a critical role in determining the detection performance. Herein, a silver nanocubes/polyelectrolyte/gold film sandwich structure was prepared as a reproducible, high-performance SERS substrate by the water/oil interfacial assembly method. In addition to the hot spots on the nanocubes surface, the edge-to-edge interspace of the Ag nanocubes led to marked enhancement of the SERS intensity, with a limit of detection of 10^?11 mol/L and limit of quantitation of 10^?10 mol/L for crystal violet. When rhodamine 6G and crystal violet were co-adsorbed on the Ag nanocube surfaces, the characteristic SERS peaks of the two molecules remained well resolved and separated, and the peak intensities varied with the respective concentration, which could be exploited for concurrent detection of dual molecules. Results from this work indicate that organized ensembles of Ag nanocubes can serve as effective SERS substrate can for sensitive analysis for complex molecular systems.     

Detecting trace melamine in solution by SERS using Ag nanoparticle coated poly(styrene-co-acrylic acid) nanospheres as novel active substrates

A systematic study for the preparation of Ag nanoparticle (Ag-NP) coated poly(styrene-co-acrylic acid) (PSA) composite nanospheres by in situ chemical reduction is reported. The experimental results showed that the reaction temperature and the surface coverage of the -COOH determined the surface coverage and grain size of Ag nanoparticles on the PSA nanospheres. The surface enhanced Raman spectroscopy (SERS) sensitivity was investigated using 4-hydroxythiophenol (4-HBT) as the model probe in the solution of composite nanospheres stabilized by polyvinylpyrrolidone (PSA/Ag-NPs/PVP), with the detection limit of about 1 × 10(-6) M. Potential application of the new SERS substrate was demonstrated with the detection of melamine, and the detection limit was about 1 × 10(-3) M. Chemical noises from PVP and other impurities were observed and attributed mainly to the competitive adsorption of PVP on the surfaces of Ag-NPs. After tetrahydrofuran washing of the PSA/Ag-NPs/PVP substrates that removed the PVP and other residuals, the signal/noise levels of SERS were greatly improved and the detection limit of melamine was determined to be 1 × 10(-7) M. This result indicated that the new PSA/Ag-NPs system is highly effective and can be used as the SERS-active substrate for trace analysis of a variety of drugs and food additives.