基于贵金属纳米颗粒的表面增强拉曼光谱基底的构建及应用
文献类型：学位论文
| 作者 | 张宗绵 |
| 学位类别 | 博士 |
| 答辩日期 | 2015-05 |
| 授予单位 | 中国科学院研究生院 |
| 授予地点 | 北京 |
| 导师 | 刘景富 |
| 关键词 | 表面增拉曼光谱，基底构建，核壳结构，浊点萃取，TLC-SERS,Surface Enahnced Raman Scattering, Construction of the Substrate, Shell-isolated structure, Cloud Point Extraction, TLC-SERS |
| 其他题名 | Construction and Application of Noble Metal Nanoparticle- Based Surface Enhanced Raman Scattering Substrate |
| 学位专业 | 分析化学 |
| 中文摘要 | 作为目前最具有吸引力的光谱技术之一，表面增强拉曼散射（Surface Enhanced Raman Scattering，SERS）技术不仅能够实现高灵敏度的单分子检测，还可以在提供其浓度信息的同时提供其结构信息，并且还具有操作简便，样品准备时间短和无损检测的特点，已经在拉曼标记，化学反应的原位监控，文物鉴定和生化分析等方面得到了应用。因为 SERS信号强烈依赖于增强基底的纳米特征及目标分子与基底之间的距离，研究者使用各种方法构建具有高增强因子和高稳定性的表面增强拉曼基底用于目标物的分析检测。本研究在不同研究体系中构建了基于贵金属纳米颗粒不同的 SERS基底，分别用于食品表面添加剂的分析检测、水体中污染物的快速分离检测和化学反应过程的原位监控。 首先，文章中以具有核壳结构的 Au@SiO2纳米颗粒为SERS基底，建立了一种以 SERS技术原位、快速检测食品中非法添加剂酸性橙 II的新方法。实验中研究了活性硅加入量对所形成的核壳结构的 Au@SiO2纳米颗粒的 SERS活性的影响，制备了具有最佳 SERS活性的 Au@SiO2纳米颗粒，并以此为SERS基底建立了酸性橙 II的分析检测方法，在硅片上可实现低至0.17mg/L酸性橙II的 SERS检测。将合成的Au@SiO2纳米颗粒滴加到瓜子表面后，可以实现对瓜子表面酸性橙 II浓度为 0.01 mg/g时的 SERS检测。该方法能够满足食品中酸性橙 II的测定要求，结合便携式拉曼光谱仪，本方法有望用于瓜子及其它可能被非法添加该物质的食品的现场、快速检测。 然后，结合浊点萃取（Cloud Point Extraction，CPE）对有机分子，纳米材料，金属离子等物质的分离富集能力和SERS技术的高灵敏度检测的特征，本章中发展了一种利用浊点萃取同时实现水体中孔雀石绿的分离富集和 SERS基底的构建的新方法。实验中，选用非离子表面活性剂Triton X-114作为浊点相实现以对水体中孔雀石绿和添加的纳米银的萃取分离。为了获得具有更佳 SERS活性的纳米银基底和最佳的萃取效率，实验中优化了溶液的 pH值和添加的纳米银和NaCl的浓度。在最佳实验条件下实现了对水体中孔雀石绿的分离检测。结果证明，在实际水体中孔雀石绿的浓度为10-11 M ~ 3×10-9范围内，所获得的SERS响应强度与其浓度呈现良好的线性关系。本方法不仅适用于可以直接进行浊点萃取的有机分子的SERS分析，还可以通过目标物与纳米银的共价或非共价结合作用，利用浊点萃取在实现对纳米银的萃取的同时实现对那些不能直接被萃取的物质的分离富集，然后以纳米银为增强基底便可以实现目标物的 SERS检测。实验中,为实现对不能直接被CPE萃取的小分子（SCN）的检测，先向待测样品中加入纳米银-胶体，利用硫氰酸根（ SCN-）与纳米银的结合作用，通过浊点萃取在实现对水体中的纳米银进行分离富集的同时便可实现对 SCN-的分离富集，而与SCN-结合的纳米银颗粒正好可以作为SERS的增强基底实现对SCN-的高灵敏度检测。实验中同样首先优化了溶液的pH值和所添加的纳米银和氯化钠的浓度，在最佳的实验条件下对水体中加入的SCN-浓度进行SERS分析检测。结果显示，在水体中硫氰酸根浓度为10μmol/L ~ 2 mmol/L的浓度范围内，其SERS响应强度与所加入的浓度呈现良好的线性相关性。这种方法操作简单，有望用于对水体中污染物的快速分离检测。 最后，我们将 SERS光谱与薄层色谱分离技术相结合（TLC-SERS），构建了一种可以原位、快速监控化学反应过程的新方法。本研究中，首先将混合物样品在薄层色谱板上进行分离，然后通过一个纳米喷雾器在 TLC板表面喷洒一层均匀的纳米金颗粒作为 SERS的增强基底，最后将其置于拉曼光谱仪上便可以进行连续的 SERS检测。实验中首先优化了所需喷洒纳米金的粒径及浓度，结果显示，喷洒浓度为 5.54× 10 10N/cm2粒径为42 nm的纳米金于分离后的薄层色谱板上，便可以获得稳定的并且具有极强信号增强效果的 SERS基底。在优化的实验条件下，在薄层色谱板上对 2-苯吡啶进行SERS测定，2-苯吡啶的特征拉曼谱峰（755 cm−1处）的峰面积与其浓度在 2 - 200 mg/L范围内呈现良好的线性关系，检出限约为 1 mg/L，这比在通常有机合成反应体系中的化学成分的浓度低得多，说明本方法有望实现对化学反应过程的监控。选用苯硼酸与 2-溴吡啶的 Suzuki偶联反应为实验模型，利用该方法对其反应过程进行了监控。结果表明，利用本方法可实时监控苯硼酸与 2-溴吡啶的偶联反应，并且采用连续的 SERS检测还可以检测到肉眼看不见的反应产物，也能够区分具有相近比移值的容易发生重叠的物质（如，2-溴吡啶与 2-苯吡啶）。利用本方法对该反应的产率进行监控，可以获得与超高效液相色谱-质谱联用（UPLC-MS/MS）完全相吻合的测定结果。另外，在连续的 SERS检测过程中还发现了一个反应副产物，并通过拉曼光谱对其结构组成进行了分析。这种新型的 TLC-SERS分析方法操作简便，成本低廉、灵敏度高，可以用于原位的监测化学反应过程，包括环境过程和生物过程。 |
| 英文摘要 | Surface enhanced Raman scattering (SERS), as one of the most attractive spectrum technologies, can not only realize the high sensitivity of the single molecule detection, but also provide both the concentration information and structure of the target analyte. Because of its easy operation, short sample preparation time and nondestructive testing property, SERS has been used in Raman labels, monitoring of chemical reactions, identification of cultural relics and biochemical analysis. As the strength of SERS signal relies on the nanostructure characters of the SERS substrates, researchers are focusing on the construction of SERS substrate with high enhanced factors and high stability. In this dissertation, we constructed several SERS substrates with gold/silver nanoparticles, and realized the detection of the illegal additives on the food surface, concentration and detection of pollutants in the water samples, and on-site monitoring of the chemical reactions. Shell-isolated Au@SiO2 nanoparticles are prepared as the SERS subatrate for fast and in situ detection of Acid Orange II on food. This shell-isolated Au@SiO2 nanoparticles are obtained by the addition of active silica to the gold colloidal solution, with (3-Aminopropyl) trimethoxysilane (APTMS) as the coupling agent at pH 8.5. By regulating the amount of the active silica, a series of Au@SiO2 nanoparticles with different silica shell thickness are synthesized. Ultraviolet–visible spectroscopy (UV-Vis) and transmission electron microscope (TEM) are employed to characterize the optical property and morphology of the as-synthesized Au@SiO2 nanoparticles. The amount of the active silica added in preparation the Au@SiO2 is optimized through comparing the SERS intensity of Acid Orange II. Under the optimized experimental conditions, Acid Orange II on the Si wafer can be detected at concentrations below 0.17 mg/L. The feasibility of the proposed method for detecting Acid Orange II in real samples is verified by spreading the Au@SiO2 nanoparticles on the surface of the watermelon seeds stained with Acid Orange II.Results showed that this novel method is capable of detecting 0.01 mg/g Acid Orange II stained on the watermelon seeds. This proposed method was applied to assay sunflower seeds and watermelon seeds purchased from local stores. It is expected that this proposed method is applicable for in situ detection of Acid Orange II on the surface of other food samples. As an effective and environment-friendly liquid–liquid extraction method, cloud point extraction (CPE) has been widely used in separation and preconcentration of inorganic ions, organic compounds, nanoparticles, and biomacromolecules. In this study, CPE was used for simultaneous preconcentration of pollutants in water and construction of SERS substrate by silver nanoparticles. Silver nanoparticles were introduced to water samples and CPE was carried out to obtain the concentrated pollutants and SERS substrate, which were uptake into a glass capillary for SERS detection. The pH and the concentration of silver nanoparticles and NaCl were optimized, and a good linearity between the SERS response and malachite greenconcentrations from 30 pmol/L to 3 nmol/L was obtained in the water samples.Based on their adsorbtion on the metal nanoparticles, this method is also used to co-extract small molecules like thiocyanate ion (SCN-) that can not be extracted by CPE directly. A good linear relationship between the SERS response and KSCN concentration in the range of 10 μmol/L - 2 mmol/L was obtained for water samples.This method is easy to handle, sensitive, and can be exploited to separate and detect trace amounts pollutants in water. Coupling SERS with thin layer chromatography (TLC), a facile and powerful method was developed for on-site monitoring the process of chemical reactions.Samples were pre-separated on a TLC plate following a common TLC procedure, and then determined by SERS after fabricating a large area uniformed SERS substrate on the TLC plate through spraying gold nanoparticles. Reproducible and strong SERS signals were obtained with substrates prepared by spraying 42 nm gold nanoparticles at a density of 5.54×1010 N/cm2 on the TLC plate. The capacity of this TLC-SERS method was evaluated by monitoring a typical Suzuki coupling reaction of phenylboronic acid and 2-bromopyridine as a model. Results showed that this proposed method is able to identify reaction product that is invisible by naked eyes, and distinguish the reactant 2-bromopyridine and product 2-phenylpyridine which showed almost the same retention factors (Rf). Under the optimized conditions, the peak area of the characteristic Raman band(755cm 2-phenylpyridine showed a good linear correlation with concentration in the range of 2 ~ 200 mg/L (R2 =0.9741), the estimated detection limit (1 mg/L 2-phenylpyridine) is ) of the product much lower than the concentration of the chemicals in the common organic synthesis reaction system, and the product yield determined by the proposed TLC-SERS method agreed very well with that by ultra-performance liquid chromatography tandem mass-spectrometry (UPLC-MS/MS). Additionally, a new by-product in the reaction system was found and identified through continuous Raman detection from the point of sample to the solvent front. This facile TLC-SERS method is quick, easy to handle, low cost, sensitive, and can be exploited in on-site monitoring the processes of chemical reactions, as well as environmental and biological processes. |
| 源URL | [http://ir.rcees.ac.cn/handle/311016/34479]  |
| 专题 | 生态环境研究中心_环境化学与生态毒理学国家重点实验室 |
| 推荐引用方式 GB/T 7714 | 张宗绵. 基于贵金属纳米颗粒的表面增强拉曼光谱基底的构建及应用[D]. 北京. 中国科学院研究生院. 2015. |
入库方式： OAI收割
来源：生态环境研究中心
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