SERS中的活性基底

从表面增强拉曼光谱(SERS)在分析科学、表面科学固体表面物理化学及纳米科学应用方面活性SERS基底的角度,总结了SERS研究中制备相对简便而有效的活性基底;对金、银胶体、棒、线、立方体状纳米金银、金银复合纳米粒子、有序金属纳米粒子组装阵列及电极的SERS基底的方法技术、基本原理、应用及其最新进展进行了概述。希望以此为SERS工作者提供参考。     

表面增强拉曼光谱基底研究进展

表面增强拉曼光谱(SERS)由于具有拉曼峰强、检测灵敏度高、能够无损分析等特点,在生物传感、表面吸附、储能、转化、文物等领域应用广泛,而制备出均匀分散并且高稳定性和重现性SERS基底是SERS技术的前提.对表面增强拉曼光谱技术的基底以及机理进行了综述.     

应用表面增强拉曼光谱检测儿童化妆品中二噁烷的研究

文章以金纳米粒子作为表面增强拉曼散射(SERS)基底,用SERS法检测儿童化妆品中的二噁烷含量。探讨了儿童化妆品中其它物质和金纳米粒子作为SERS基底对儿童化妆品中二噁烷SERS特征峰的影响。     

Ag/双晶TiO_2作为表面增强拉曼散射基底的性能研究

通过化学还原法将Ag纳米粒子担载到锐钛/TiO2(B)双晶材料上,并将其作为表面增强拉曼散射(SERS)基底,用于有机探针分子4-巯基苯甲酸的痕量检测。研究表明:双晶氧化钛特殊的能带结构有利于光响应过程中电子-空穴的定向转移,从而比纯锐钛矿具有更优异的电子转移能力,因此能够得到更佳的SERS性能。这种现象表明,双晶氧化钛材料是SERS技术应用到检测领域的理想载体。     

基于LSPR效应的高活性SERS基底研究进展

简要介绍了表面增强拉曼散射(SERS)的发展历程及拉曼增强机理,重点综述了不同类型SERS基底:简单SERS基底、复合SERS基底和多功能活性基底的特点和研究应用进展,最后展望了SERS基底的研究方向和发展趋势。     

SERS基底Ag@Au的制备及其对氧氟沙星的检测

通过种子介导生长方法,合成了形貌、粒径均一,分散性良好的双金属Ag@Au纳米粒子,并将其作为表面增强拉曼散射（SERS）基底,对氧氟沙星（OFLX）进行检测。首先在最佳实验条件下对氧氟沙星主要拉曼峰进行归属,选取1 416 cm ^-1拉曼特征峰。其次,对其1 416 cm ^-1特征峰强度与氧氟沙星浓度作线性拟合,曲线方程为Y=291.48X+3 156.8,r=0.989,检测极限可达10 ^-10 mol/L。该方法操作简单,灵敏度高,重现性好,可为氧氟沙星类抗生素药物的SERS检测提供依据。     

金纳米星的制备及对塑化剂的快速检测

采用两步法合成了金纳米星,通过消光光谱和透射电镜的表征,发现金纳米星的表面有多个针尖状纳米结构。针尖状结构末端的尺寸5～10 nm,可形成多个拉曼热点。将其作为表面增强拉曼散射(SERS)活性基底,通过拉曼光谱检测了塑化剂DBP的含量,检出限可达到10 ng。金纳米星可作为一种灵敏的SERS活性基底为食品、生活用品等环境中的塑化剂提供快速的检测。     

自组装纳米阵列SERS基底的发展及应用进展

表面增强拉曼散射(SERS)的谱峰窄以及分子指纹特性使其在分析化学、环境检测、生物医药及食品安全等领域具有广泛应用。而稳定、均一、重复性好的SERS活性基底的制备至关重要。自组装法可制备出均一、稳定、高度有序、可控的纳米阵列,提高SERS检测的重现性和灵敏度。本文对自组装纳米阵列技术制备SERS活性基底及SERS的应用进行了综述。     

金纳米双锥体的制备及对食品污染物的快速检测

制备了一种新颖、可靠、快速的检测平台用于检测食品中多种化学污染物。通过种子两步生长法合成出金纳米双锥体,采用消耗诱导分离法获得纯度接近100%的金纳米双锥体,利用液-液界面自组装法制备出大面积致密的金纳米双锥体表面增强拉曼散射（SERS）活性基底。研究表明,以结晶紫（CV）作为拉曼探针分子,该基底具有较好的SERS灵敏性和重复性;而且对抗生素孔雀石绿（MG）、农药残留福美双（THR）和塑化剂邻苯二甲酸卞酯（BBP）的检测灵敏性较高,检测限分别达到10^-9、10^-9、10^-8 mol/L,对酒中BBP的检测限为1.3 mg/kg。     

MOF@ Ag-TiN纳米管阵列复合SERS基底构筑及性能研究

通过阳极氧化结合氨气还原氮化法制备了氮化钛纳米管阵列结构，再利用电化学沉积技术结合原位生长法制备出MOF@Ag-TiN复合SERS基底。结果表明，所制备的MOF@Ag-TiN复合基底存在面心立方晶型TiN、银单质和钴基MOF三种物相，通过扫面电镜技术发现TiN纳米管阵列结构均匀完整，银纳米粒子均匀分布在阵列结构表面，同时基底表面包覆有形状规则的MOF纳米粒子。MOF@Ag-TiN复合基底具有较好的拉曼增强性能，对探针分子R6G的检测限为10^-12 M,同时还具有良好的稳定性。     

Recent Advances in Metallic Nanoparticle Assemblies for Surface-Enhanced Spectroscopy

Robust and versatile strategies for the development of functional nanostructured materials often focus on assemblies of metallic nanoparticles. Research interest in such assemblies arises due to their potential applications in the fields of photonics and sensing. Metallic nanoparticles have received considerable recent attention due to their connection to the widely studied phenomenon of localized surface plasmon resonance. For instance, plasmonic hot spots can be observed within their assemblies. A useful form of spectroscopy is based on surface-enhanced Raman scattering (SERS). This phenomenon is a commonly used in sensing techniques, and it works using the principle that scattered inelastic light can be greatly enhanced at a surface. However, further research is required to enable improvements to the SERS techniques. For example, one question that remains open is how to design uniform, highly reproducible, and efficiently enhancing substrates of metallic nanoparticles with high structural precision. In this review, a general overview on nanoparticle functionalization and the impact on nanoparticle assembly is provided, alongside an examination of their applications in surface-enhanced Raman spectroscopy.     

Determination of the Molecular Structure of Interphases Between Epoxy/4,4'-Diaminodiphenylsulfone Adhesives and Silver Substrates Using SERS and XPS

The molecular structure of interphases formed by curing an epoxy/4,4'-diaminodiphenylsulfone (DADPS) adhesive against rough silver substrates was determined using surface-enhanced Raman scattering (SERS) and x-ray photoelectron spectroscopy (XPS). SERS spectra obtained from the adhesive deposited onto silver island films were very similar to SERS spectra obtained from the DADPS curing agent spun onto silver island films, indicating that DADPS in the adhesive system segregated to the interphase and was preferentially adsorbed onto the silver substrate. Differences in the relative intensity of several bands in the normal Raman and SERS spectra of DADPS were observed. For example, the band near 1603 cm^-1 was stronger in SERS spectra of DADPS than in normal Raman spectra. The band near 1150 cm^-1 was weaker in SERS spectra of DADPS than in normal Raman spectra. These results implied that DADPS was adsorbed through one of the NH groups with an end-on conformation. Consistent results were also obtained from XPS spectra. C(ls) spectra of the adhesive and silver fracture surfaces of specimens prepared by curing the adhesive against silver substrates were more similar to the C(ls) spectra of DADPS than to those of the bulk adhesive. These results confirmed the preferential adsorption of DADPS onto the silver substrate from the adhesive system. The similarity of the C(ls) spectra obtained from adhesive and silver fracture surfaces indicated that a thin DADPS-rich interphase was formed between the bulk adhesive and the silver substrate and that the locus of failure was partially within this layer. However, less nitrogen and sulfur were detected on the silver fracture surface than on the adhesive fracture surface. A large amount of silver was observed on the substrate fracture surface and a trace was found on the adhesive fracture surface. These results indicated that failure of the adhesive joints was within the interphase but near the silver substrate. No evidence of chemisorption of DADPS onto the substrate was observed.     

Controlled fabrication of silver nanoneedles array for SERS and their application in rapid detection of narcotics

Novel surface-enhanced Raman scattering (SERS) substrates with high SERS-activity are ideal for novel SERS sensors, detectors to detect illicitly sold narcotics and explosives. The key to the wider application of SERS technique is to develop plasmon resonant structure with novel geometries to enhance Raman signals and to control the periodic ordering of these structures over a large area to obtain reproducible Raman enhancement. In this work, a simple Ar(+)-ion sputtering route has been developed to fabricate silver nanoneedles arrays on silicon substrates for SERS-active substrates to detect trace-level illicitly sold narcotics. These silver nanoneedles possess a very sharp apex with an apex diameter of 15 nm and an apex angle of 20°. The SERS enhancement factor of greater than 10(10) was reproducibly achieved by the well-aligned nanoneedles arrays. Furthermore, ketamine hydrochloride molecules, one kind of illicitly sold narcotics, can be detected down to 27 ppb by using our SERS substrate within 3 s, indicating the sensitivity of our SERS substrates for trace amounts of narcotics and that SERS technology can become an important analytical technique in forensic laboratories because it can provide a rapid and nondestructive method for trace detection.     

Polytetrafluorethylene-Au as a substrate for surface-enhanced Raman spectroscopy

This study deals with preparation of substrates suitable for surface-enhanced Raman spectroscopy (SERS) applications by sputtering deposition of gold layer on the polytetrafluorethylene (PTFE) foil. Time of sputtering was investigated with respect to the surface properties. The ability of PTFE-Au substrates to enhance Raman signals was investigated by immobilization of biphenyl-4,4'-dithiol (BFD) from the solutions with various concentrations. BFD was also used for preparation of sandwich structures with Au or Ag nanoparticles by two different procedures. Results showed that PTFE can be used for fabrication of SERS active substrate with easy handle properties at low cost. This substrate was sufficient for the measurement of SERS spectrum of BFD even at 10-8 mol/l concentration.     

Large-area high-performance SERS substrates with deep controllable sub-10-nm gap structure fabricated by depositing Au film on the cicada wing

Noble metal nanogap structure supports strong surface-enhanced Raman scattering (SERS) which can be used to detect single molecules. However, the lack of reproducible fabrication techniques with nanometer-level control over the gap size has limited practical applications. In this letter, by depositing the Au film onto the cicada wing, we engineer the ordered array of nanopillar structures on the wing to form large-area high-performance SERS substrates. Through the control of the thickness of the Au film deposited onto the cicada wing, the gap sizes between neighboring nanopillars are fine defined. SERS substrates with sub-10-nm gap sizes are obtained, which have the highest average Raman enhancement factor (EF) larger than 2 × 10⁸, about 40 times as large as that of commercial Klarite® substrates. The cicada wings used as templates are natural and environment-friendly. The depositing method is low cost and high throughput so that our large-area high-performance SERS substrates have great advantage for chemical/biological sensing applications.     

SERS substrates formed by gold nanorods deposited on colloidal silica films

We describe a new approach to the fabrication of surface-enhanced Raman scattering (SERS) substrates using gold nanorod (GNR) nanopowders to prepare concentrated GNR sols, followed by their deposition on an opal-like photonic crystal (OPC) film formed on a silicon wafer. For comparative experiments, we also prepared GNR assemblies on plain silicon wafers. GNR-OPC substrates combine the increased specific surface, owing to the multilayer silicon nanosphere structure, and various spatial GNR configurations, including those with possible plasmonic hot spots. We demonstrate here the existence of the optimal OPC thickness and GNR deposition density for the maximal SERS effect. All other things being equal, the analytical integral SERS enhancement of the GNR-OPC substrates is higher than that of the thick, randomly oriented GNR assemblies on plain silicon wafers. Several ways to further optimize the strategy suggested are discussed.     

Fabrication of nanowire network AAO and its application in SERS

In this paper, nanowire network anodized aluminum oxide (AAO) was fabricated by just adding a simple film-eroding process after the production of porous AAO. After depositing 50 nm of Au onto the surface, nanowire network AAO can be used as ultrasensitive and high reproducibility surface-enhanced Raman scattering (SERS) substrate. The average Raman enhancement factor of the nanowire network AAO SERS substrate can reach 5.93 × 10⁶, which is about 14% larger than that of commercial Klarite® substrates. Simultaneously, the relative standard deviations in the SERS intensities are limited to approximately 7%. All of the results indicate that our large-area low-cost high-performance nanowire structure AAO SERS substrates have a great advantage in chemical/biological sensing applications.     

Interfacial potassium induced enhanced Raman spectroscopy for single-crystal TiO2 nanowhisker

Structural control and element doping are two popular strategies to produce semiconductors with surface enhanced Raman spectroscopy(SERS) properties. For TiO_2 based SERS substrates, maintaining a good crystallinity is critical to achieve excellent Raman scattering. At elevated temperatures(N600 °C), the phase transition from anatase to rutile TiO_2 could result in a poor SERS performance. In this work, we report the successful synthesis of TiO_2 nanowhiskers with excellent SERS properties. The enhancement factor, an index of SERS performance, is 4.96 × 10~6 for methylene blue molecule detecting, with a detection sensitivity around 10~(-7) mol·L~(-1).Characterizations, such as XRD, Raman, TEM, UV–vis and Zeta potential measurement, have been performed to decrypt structural and chemical characteristics of the newly synthesized TiO_2 nanowhiskers. The photo absorption onset of MB adsorbed TiO_2 nanowhiskers was similar to that of bare TiO_2 nanowhiskers. In addition, no new band was observed from the UV–vis of MB modified TiO_2 nanowhiskers. Both results suggest that the high enhancement factor cannot be explained by the charge-transfer mechanism. With the support of ab initio density functional theory calculations, we reveal that interfacial potassium is critical to maintain thermal stability of the anatase phase up to 900 °C. In addition, the deposition of potassium results in a negatively charged TiO_2 nanowhisker surface, which favors specific adsorption of methylene blue molecules and significantly improves SERS performance via the electrostatic adsorption effect.     

Cystine-assisted accumulation of gold nanoparticles on ZnO to construct a sensitive surface-enhanced Raman spectroscopy substrate

Recently, various semiconductor/metal composites have been developed to fabricate surface-enhanced Raman spectroscopy substrates. However, low metal loading on semiconductors is still a challenge. In this study, cystine was introduced to increase the accumulation of gold nanoparticles on zinc oxide, owing to the biomineralization property of cystine. Morphological analysis revealed that the obtained ZnO/Au/cystine composite not only had a higher metal loading but also formed a porous structure, which is beneficial for Raman performance. Compared with ZnO/Au, the ZnO/Au/cystine substrate displayed a 40-fold enhancement in the Raman signal and a lower limit of detection (10^–11 mol·L⁻¹) in the detection of rhodamine 6G. Moreover, the substrate has favorable homogeneity and stability. Finally, ZnO/Au/cystine displayed excellent performance toward crystal violet and methylene blue in a test based on river water samples. This study provided a promising method to fabricate sensitive semiconductor/noble metal-based surface-enhanced Raman spectroscopy substrates for Raman detection.