表面增强拉曼散射活性基底的制备

表面增强拉曼散射是一种新型光学物质检测方法,与传统的气相色谱分析和质谱分析等方法相比,具有高灵敏度、高分辨率和可猝灭荧光等优点。而活性基底表面形态是SERS效应能否发生和SERS信号强弱的重要影响因素．本文分析介绍了5种表面增强拉曼散射活性基底的制备方法,对其实际应用效果做了简要分析。     

三种不同银纳米粒子SERS基底比较研究

表面增强拉曼光谱(SERSp)技术是一种新兴的分析检测技术,由于其对样品分析灵敏度高、检测时间短以及样品所需量小等优点,近年来该技术已在生物医学,化学等领域得到广泛的应用,同时表面增强拉曼散射(SERS)基底的制备已成为该领域的研究热点。本文主要对三种以银纳米粒子(AgNPs)的SERS效应为基质的拉曼活性基底:毛细管-AgNPs,二氧化钛-AgNPs和滤纸-AgNPs进行比较研究。首先分别用三种基底对罗丹明6G(R6G)分子进行拉曼光谱采集及分析,找出三种SERS基底相应的最佳制备条件。最后用这三种最佳条件下制备的SERS基底对同一个健康人血清进行拉曼光谱检测,并对结果进行分析比较。初步结果:三种SERS基底都是可靠的和实用的;二氧化钛-AgNPs基底灵敏度相对较高,但制备过程较复杂;滤纸-AgNPs基底灵敏度其次;毛细管-AgNPs基底及滤纸-AgNPs基底的制备均较为简单。因此,从实用角度考虑,滤纸-AgNPs基底比较适合血清的表面增强拉曼光谱检测与分析。     

氧化锌/贵金属复合表面增强拉曼散射基底的研究进展

近年来,随着纳米技术的快速发展,表面增强拉曼散射(SERS)技术已广泛应用于物理化学、材料科学、表面科学以及生物科学等领域。基于氧化锌/金属复合SERS基底,因其具有高拉曼增强性能及优异的循环利用性能,正逐渐成为SERS技术的研究热点之一。本文综述了氧化锌复合SERS基底的机制、制备、调控和应用的研究进展,并在基础上分析了相关研究趋势,从而为高性能可循环利用SERS基底的开发与增强机制的研究提供重要参考。     

一种新型表面增强拉曼活性基底的制备及表征

研究了一种新的表面增强拉曼活性银基底的制备方法,采用银增强剂和引发剂的混合溶液处理全铝表面制备了银基底,利用扫描电子显微镜分析了基底的表面形态和结构,测定结晶紫分子在基底表面的拉曼光谱.结果表明,这种基底具有很强的表面增强拉曼散射效应(SERS)活性和稳定性.     

基于微球自组装技术的大面积表面增强拉曼基底研究

表面增强拉曼光谱(surface-enhanced Raman scattering,SERS)能够有效解决常规拉曼中信号极弱问题,在低浓度分析物的痕量检测甚至单分子的检测中具有重要的应用前景,是化学、生物、环境等领域重要的分析手段。在SERS中,高性能SERS基底的实现是关键。本文以微球自组装技术为基础,制备了一种大面积、廉价、高效的SERS基底并对其进行了形貌表征和拉曼增强光谱研究。通过开展R6G分子的SERS研究发现,此种SERS基底对R6G拉曼散射信号的增强倍数是一般粗糙基底的五倍以上。结合数值模拟分析和系统的实验研究,得到了微球直径、纳米颗粒的高度等参数对基底表面附近局域热点和SERS增强倍数的影响规律,给出了最优化的SERS基底参数。本文工作可为SERS研究提供高性能的SERS基底。     

Ag纳米粒子修饰聚合物纳米尖锥阵列的SERS衬底制备

表面增强拉曼散射(SERS)以其无损、超灵敏、快速检测分析等优点而备受关注,在化学和生物传感等应用领域有着极大的潜力。研制灵敏度高、重复性强、稳定性好的SERS基底,对于实现其在痕量分析、生物诊断中的实际应用具有重要意义。具有微/纳米结构的聚合物具有优异的机械性能、光学性能、耐化学性等优点。通过模板压印法,利用多孔阳极氧化铝(AAO)在聚合物聚碳酸酯(PC)表面制备一种高度有序的纳米PC尖锥阵列结构,然后通过蒸发镀膜在PC尖锥阵列上沉积一层银膜,制备了大面积Ag纳米颗粒修饰的高度有序聚合物纳米尖锥阵列。高曲率纳米针状结构顶端的银颗粒及颗粒之间狭小的纳米间隙能产生大量的SERS"热点"。这种方法得到了均匀,可重复,大面积高增强的SERS活性基底,并进一步研究了不同沉积厚度银膜的SERS特性。用扫描电子显微镜(SEM)对其进行了表征,以结晶紫作为探针分子对这种结构进行研究。结果表明:拉曼信号强度随银厚度的增加显示为先增强后减弱的趋势。基底对结晶紫的拉曼增强因子达到5.4×10~6,基底主要拉曼峰强度的RSD为10%,说明该基底具有很好的检测灵敏性和重复性。此外,基底在存放40 d后,在相同条件下仍然保持着高SERS性能,表现出很好的稳定性。整个制备过程简单易行,重复性好,制作成本非常低廉,而且能够规模化制备,可方便地作为活性基底应用于SERS研究,必将具有广阔的研究和应用前景。     

表面增强拉曼散射胶带:一种原位检测平台

基于局域表面等离基元共振的原理,表面增强拉曼光谱(SERS)技术因其具有灵敏度高、使用方便、能提供近场增强的优点,广泛用于催化、光谱电化学、传感等领域[1-2]。表面增强拉曼基底是SERS的核心,硅片、玻璃片是最常用的用于制备SERS基底的衬底材料,然而他们的刚性特征限制了其应用范围。我们提出了一种简单的制备表面增强拉曼散射胶带的方法,利用胶带的粘性特征直接将沉积在刚性硅片表面的纳米结构转移至胶带表面。需要用时直接将胶带撕下来贴在需要检测的位置上,这种表面增强拉曼散射胶带可灵活方便用于固体、液体的原位检测和研究。     

银纳米有序阵列SERS活性基底的制备及在膀胱肿瘤细胞检测中的应用

以多孔阳极氧化铝(porous anodic alumina,PAA)膜为模板,采用真空电子束蒸镀技术,分别在PAA多孔层以及阻挡层表面形成了银纳米孔和银纳米帽有序阵列表面增强拉曼散射(surface-enhancedRaman scattering,SERS)活性基底,并以膀胱肿瘤细胞作为分子探针,测试和分析了这两种SERS活性基底的表面增强拉曼光谱的特性。结果表明,两种SERS活性基底对膀胱肿瘤细胞的拉曼散射信号均有很好的增强作用。银纳米帽有序阵列SERS活性基底不仅具有较高的SERS增强和荧光猝灭效应,而且不存在与PAA膜中草酸根杂质相关的干扰峰,可获得膀胱肿瘤细胞拉曼散射光谱的更多细节信息。     

仿生表面增强拉曼散射基底的制备及其生物分析应用

经过数十亿年的进化和发展,自然界中的动植物体表面形成了规则的微/纳米结构和奇特功能。仿生表面增强拉曼散射(Surface enhanced Raman scattering, SERS)基底是以动植物体表面固有的规则结构或与动植物体性能相似的材料为基础而制作的基底,自发现以来,已成为SERS基底制备领域的研究热点,为解决传统SERS基底形貌和结构不均一、重现性差的问题提供了新的思路。本文介绍了仿生SERS基底及其制备方法,总结了仿生SERS基底在生物分析等方面的应用,并对其在今后的发展做了初步的展望。     

银溶胶自组装表面增强光纤拉曼探针的研究

利用表面增强拉曼 (SERS)技术对光纤表面进行修饰 ,构造了表面增强光纤拉曼光谱传感器。选取了几个有代表性的分子作为检测样品 ,得到了低浓度样品的SERS光谱。结果表明 ,可以将制备SERS活性基底的方法移植到光纤表面来制备SERS活性光纤探针。     

农药残留检测中表面增强拉曼光谱的研究进展

农药直接污染环境和食物,最终被人体吸收。其残留物具有高毒性,对人体健康造成严重影响。色谱法、气液色谱串联质谱法等在农药残留检测中应用较为广泛,但存在预处理步骤复杂、费时耗力等缺点。表面增强拉曼光谱（SERS）技术因具备灵敏度高、特异性好、提供全面指纹信息且对样品无损等优点被视为一种新型农残检测方法,可通过简单提取实现液体或固体样品中痕量农药残留的高效检测。在这篇综述中,主要从SERS的增强基底制备、检测方法以及光谱智能解析三个方面对农药残留SERS检测技术及方法的研究进展进行综述,以期为农药残留检测方法提供新的参考。首先,针对SERS增强基底制备,单一的贵金属溶胶纳米颗粒因其“热点”随机、不可控等因素导致稳定性和灵敏性较差,已不能满足痕量农药残留检测。为提高SERS基底的吸附能力使待测物在其表面富集且信号不发生显著变化,对单一贵金属溶胶纳米颗粒进行组装,或加入化学物质、惰性材料等进行修饰制备均一性高的SERS复合基底,保证SERS信号有良好的重现性和灵敏性。其次,为了实现特异性和高灵敏检测,SERS检测方法不再只以单纯的金、银纳米颗粒作为增强基底,而是逐渐趋向于优化样本前处理技术、化学修饰法制备特异性SERS探针、基底物理结构突破以及动态SERS（D-SERS）检测等方向发展。在获得物质的拉曼光谱后,有效拉曼特征区通常在较短的波数范围内,而光谱数据高达上千维,冗余较多,导致后续分析复杂度增加。SERS光谱智能分析则采用化学计量学方法对原始光谱进行预处理、特征提取和模型构建,实现数据降维和主要信息提取,进而实现农残的定性与定量。综上,SERS作为一种快速检测农药残留的方法具有很好的发展前景,可为今后的分析检测领域提供新的借鉴。     

Stamping plasmonic nanoarrays on SERS‐supporting platforms

The dielectric property of a nanoparticle‐supporting film has recently garnered attention in the fabrication of plasmonic surfaces. A few studies have shown that the localized surface plasmon resonance (LSPR), and hence surface‐enhanced Raman scattering (SERS), strongly depends on the substrate refractive index. In order to create higher efficiency SERS‐active surfaces, it is therefore necessary to consider the substrate property along with nanoparticle morphology. However, due to certain limitations of conventional lithography, it is often not feasible to create well‐defined plasmonic nanoarrays on a substrate of interest. Here, an additive nanofabrication technique, i.e., nanotransfer printing (nTP), is implemented to integrate electron beam lithography (EBL) defined high‐aspect‐ratio nanofeatures on a variety of SERS‐supporting surfaces. With the aid of suitable surface chemistries, a wide range of plasmonic particles were successfully integrated on surfaces of three physically and chemically distinct dielectric materials, namely, polydimethyl siloxane (PDMS), SU‐8 photoresist, and glass surfaces, using silicon‐based relief pillars. These nTP‐created metal nanoparticles strongly amplify the Raman signal and complement the selection of suitable substrates for better SERS enhancement. Our experimental observations are also supported by theoretical calculations. The implementation of nTP to stamp out metal nanoparticles on a multitude conventional/unconventional substrates has novel applications in designing in‐built plasmonic microanalytical devices for SERS sensing and other related photonic studies. Copyright © 2011 John Wiley & Sons, Ltd.     

An improved self‐assembly gold colloid film as surface‐enhanced Raman substrate for detection of trace‐level polycyclic aromatic hydrocarbons in aqueous solution

To detect trace‐level polycyclic aromatic hydrocarbons, some investigations of an improved self‐assembly method are carried out using gold colloid films for the preparation of the surface‐enhanced Raman scattering (SERS)‐active substrate. Extinction spectra and scanning electron microscopy images reveal that controllable surface plasmonic metal substrates can be obtained by increasing the temperature of (3‐aminopropyl)trimethoxysilane solution up to 64.5 °C. The SERS‐active substrates have a high enhancement factor, and they can be both easily prepared and reproducible. With the use of these substrates, different concentrations of pyrene and anthracene in aqueous solutions were detected by SERS. A further enhancement can be supported by shifted excitation Raman difference spectroscopy. Raman signals of pyrene and anthracene adsorbed on gold colloid substrates up to limits of detection at 5 and 1 nmol/l, respectively, can be obtained. The quantitative analysis shows the possibility of in situ detection of polycyclic aromatic hydrocarbons while such gold colloid film serves as a SERS‐active substrate. Copyright © 2012 John Wiley & Sons, Ltd.     

树枝状银微米材料的制备及其表面增强拉曼光谱研究

为使表面增量拉曼散射(SERS)衬底的制备方法简单快速且提高的基底增强效果,采用置换反应的制备方法,用锌片和硝酸银反应制备出微米银结构SERS活性基底,其具有稳定性好,易保存,制备方法简单,过程快速等特点。用扫描电子显微镜观察得银微米材料表面形貌呈均匀对称的树枝状结构。实验中控制置换反应的时间分别为40,50,60 s时,得到的树枝状银微米材料的长度分别为3,5,10 μm左右,分支分别为700 nm,2 μm,3 μm,发现随着置换反应的时间的增长,微米银树枝及分枝的长度越长,且树枝分枝上逐渐长出纳米级“树叶”结构, 使得微米级银树枝表面具有纳米结构。并且将微米银材料置于硅片上作为SERS衬底,并以罗丹明6G为探针分子,用激发波长为1 064 nm的傅里叶变换拉曼光谱仪检测,研究其在表面增强拉曼光谱中的应用,结果表明树枝状银微米材料有很好的SERS特性,其中置换反应时间为40 s时制备的微米银树枝的增强效果最佳,其增强因子可达到103左右,并且采用用表面活性剂PVP处理硅片的方法后,保持其他条件不变,微米银衬底的SERS增强效果得到进一步加强,增强因子达到104左右。此外,将树枝状银微米材料用水可封存数月,且实验结果的重复性较好。     

Highly efficient silver particle layers on glass substrate synthesized by the sonochemical method for surface enhanced Raman spectroscopy purposes

A fast method for preparing of silver particle layers on glass substrates with high application potential for using in surface enhanced Raman spectroscopy (SERS) is introduced. Silver particle layers deposited on glass cover slips were generated in one-step process by reduction of silver nitrate using several reducing agents (ethylene glycol, glycerol, maltose, lactose and glucose) under ultrasonic irradiation. This technique allows the formation of homogeneous layers of silver particles with sizes from 80 nm up to several hundred nanometers depending on the nature of the used reducing agent. Additionally, the presented method is not susceptible to impurities on the substrate surface and it does not need any additives to capture or stabilize the silver particles on the glass surface. The characteristics of prepared silver layers on glass substrate by the above mentioned sonochemical approach was compared with chemically prepared ones. The prepared layers were tested as substrates for SERS using adenine as a model analyte. The factor of Raman signal enhancement reached up to 5·10⁵. On the contrary, the chemically prepared silver layers does not exhibit almost any pronounced Raman signal enhancement. Presented sonochemical approach for preparation of silver particle layers is fast, simple, robust, and is better suited for reproducible fabrication functional SERS substrates than chemical one.     

Use of atomic layer deposition to improve the stability of silver substrates for in situ,high‐temperature SERS measurements

A method to stabilize silver surface‐enhanced Raman spectroscopy (SERS) substrates for in situ, high‐temperature applications is demonstrated. Silver island films grown by thermal evaporation were coated with a thin layer (from 2.5 to 5 nm) of alumina by atomic layer deposition (ALD), which protects and stabilizes the SERS‐active substrate without eliminating the Raman enhancement. The temporal stability of the alumina‐coated silver island films was examined by measurement of the Raman intensity of rhodamine 6G molecules deposited onto bare and alumina‐coated silver substrates over the course of 34 days. The coated substrates showed almost no change in SERS enhancement, while the uncoated substrates exhibited a significant decrease in Raman intensity. To demonstrate the feasibility of the alumina‐coated silver substrate as a probe of adsorbates and reactions at elevated temperatures, an in situ SERS measurement of calcium nitrate tetrahydrate on bare and alumina‐coated silver was performed at temperatures ranging from 25 to 400 °C. ALD deposition of an ultrathin alumina layer significantly improved the thermal stability of the SERS substrate, thus enabling in situ detection of the dehydration of the calcium nitrate tetrahydrate at an elevated temperature. Despite some loss of Raman signal, the coated substrate exhibited greater thermal stability compared to the uncoated substrate. These experiments show that ALD can be used to synthesize stable SERS substrates capable of measuring adsorbates and processes at high temperature. Copyright © 2009 John Wiley & Sons, Ltd.     

Improved performances on surface‐enhanced Raman scattering based on electrochemically roughened gold substrates modified with SiO2 nanoparticles

In this work, we use electrochemical oxidation–reduction cycles (ORC) methods to prepare surface‐enhanced Raman scattering (SERS)‐active gold substrates modified with SiO₂ nanoparticles to improve the corresponding SERS performances. Based on the modified substrates, the SERS of Rhodamine 6G (R6G) exhibits a higher intensity by 3‐fold of magnitude, as compared with that of R6G adsorbed on a SERS‐active Au substrate without the modification of SiO₂ nanoparticles. Moreover, the SERS enhancement capabilities of the modified and the unmodified Au substrates are seriously destroyed at temperatures higher than 250 and 200 °C, respectively. These results indicate that the modification of SiO₂ nanoparticles can improve the thermal stability of SERS‐active substrates. The aging in SERS intensity is also depressed on this modified Au substrate due to the contribution of SiO₂ nanoparticles to SERS effects. Copyright © 2009 John Wiley & Sons, Ltd.     

Improved performance of surface‐enhanced Raman scattering on silver substrates prepared in nitric acid solutions

In this work, we propose a new electrochemical method to prepare surface‐enhanced Raman scattering (SERS)‐active silver substrates in nitric acid solutions. Experimental results indicate that the SERS intensity of adsorbed Rhodamine 6G (R6G) can be significantly increased, as compared with that of R6G adsorbed on a SERS‐active Ag substrate prepared by an electrochemical method in a chloride‐containing solution, which was generally employed in the literature. Moreover, the SERS of R6G on the newly developed substrate (prepared in a nitric acid solution) still performs well at a high temperature of 250 °C. However, the enhancement capability of the SERS‐active substrate prepared in a chloride‐containing solution is seriously destroyed at temperatures higher than 150 °C. Further investigations indicate that the oxidation states of roughened Ag substrates prepared in nitric acid solutions under different experiment conditions have less influence on the corresponding SERS performances. Instead, different surface morphologies of roughened Ag substrates and different contents of nitrogen‐containing dopping ions on the roughened Ag substrates demonstrate significant effects on the corresponding SERS performances. Copyright © 2011 John Wiley & Sons, Ltd.     

Enhancements in intensity and thermal stability of Raman spectra based on roughened gold substrates modified by underpotential deposition of silver

In this study, electrochemically roughened gold is modified with underpotential deposition (UPD) silver to investigate the effects on enhancements in the intensity and the thermal stability of surface‐enhanced Raman scattering (SERS). The SERS of Rhodamine 6G (R6G) adsorbed on the UPD Ag‐modified Au substrate exhibits a higher intensity by six‐fold of magnitude, as compared with that of R6G adsorbedon the unmodified Au substrate. Moreover, the SERS enhancement capabilities of UPD Ag‐modified Au and unmodified Au substrates are seriously depressed at temperatures higher than 200 and 150 °C, respectively. It indicates that the modification of UPD Ag can significantly depress the thermal destruction of SERS‐active substrates. Copyright © 2009 John Wiley & Sons, Ltd.