人类制备和应用纳米材料已经有很长的历史。近年来，纳米材料因为具有许多其块材或分子所没有的独特的表面效应、体积效应和量子尺寸效应等性能，使得纳米材料在光学、电学、磁学、生物医学等诸多方面具有巨大的应用潜力，吸引着越来越多的人投身于纳米材料的研究。在这些研究中，尤其金、银纳米材料因其优异的光电性质，已经成为许多基础研究和实际应用研究关注的对象。

表面增强拉曼光谱（SERS）技术由于其高探测灵敏度、高分辨率、水干扰小、荧光强度相对变弱、稳定性好等优点，逐渐在生物学、诊断学、医学、材料科学、分析科学以及表面科学的研究中得到了广泛应用，显示了光明的发展前景。而金属纳米材料独特的光学、电学性质，如一定尺寸的贵金属纳米粒子可产生理想的SERS效应，特别是纳米粒子之间产生的“热点”（hot spots）效应贡献的SERS增强因子达10¹⁴。基于此，本论文进行了表面功能化的金、银纳米颗粒作为纳米化学小分子探针检测As³⁺、Ag⁺的研究。具体的研究内容如下：

1、谷胱甘肽功能化的银纳米颗粒（GSH-AgNPs）用于水体中As³⁺的高灵敏SERS检测。首先，将GSH和4-巯基吡啶（4-MPY）通过Ag-S化学键对AgNPs进行功能化，得到GSH/4-MPY功能化的AgNPs，此处GSH会通过As-O化学键与As³⁺发生特异性结合，而4-MPY的职责是拉曼信号报告分子。在水溶液中如果存在As³⁺，GSH/4-MPY功能化的AgNPs就会发生团聚，4-MPY的拉曼信号得到增强，达到间接检测水体中As³⁺的目的。通过对其灵敏度和选择性的实验研究，证明该方法表现出高的灵敏度和很好的选择性。在最佳实验条件下，该方法检测As³⁺可以达到的最低检测限为0.76ppb(S/N=3)，低于世界卫生组织（WHO）的规定（≤10ppb），并得到较宽的线性范围4-300ppb。通过对实际环境中的水样进行检测，证明该方法具有一定的实际应用价值。

2、研究基于PDMS微流控芯片技术与SERS系统联用检测水溶液中As³⁺的方法。以PDMS微流控芯片的微通道作为样品通道及检测通道，以蠕动泵作为进样推动力，并基于GSH/4-MPY功能化的AgNPs检测水溶液中的As³⁺的SERS检测，建立了一个高重现性、准确、快速、简便测定水溶液中As³⁺的微流控芯片-SERS检测新方法。利用该方法测定水溶液中的As³⁺，其线性范围为10-300ppb，检出限为3.28ppb(S/N=3)。

3、一种简单、方便的基于巯基化腺嘌呤化合物（A-SH）功能化的金纳米颗粒（A-S-AuNPs）的比色检测探针用于检测Ag⁺。本文设计合成了一种巯基化的腺嘌呤化合物（A-SH），并通过Au-S化学键对金纳米颗粒进行功能化。在水溶液中如果存在Ag⁺，A-S-AuNPs就会与其发生比色响应，达到检测水溶液中Ag⁺的目的。通过对其灵敏度的实验研究，结果显示该方法的最低检测限仅为2.6×10^-6mol/L，线性范围为8.0×10^-6~1.0×10^-4mol/L。

The preparation and application of nanomaterials have been known for a long time. In recent years, nanomaterials have been exploited for the extensive potential applications in optics, electronics, magnetics, sensing, biomedicine, etc, due to their peculiar surface effect, volume effect, and quantum effect that are different from those of bulk materials and molecular compounds. Because of these properties, nanomaterials have attracted more and more people to develop themselves into this field. Among all kinds of materials, gold and silver nanomaterials which have fascinating optical and electrical properties, have been the subjects of a number of studies for fundamental interests and practical applications.

Surface-enhanced Raman scattering (SERS) technique has been widely and potentially used in material science, surface science, biological characterization and diagnostics, because of its narrow, well-resolved bands, low SERS intensity of water and high stability. And having size effect, nanomaterials have unique optic and electric properties, for example, ideal enhanced effect was observed on definite-size Au nanoparticles, and its enhancement factor can reach to 10¹⁴ on some “hot spots” between nanoparticles. Herein, in this paper, the detection of As³⁺, Ag⁺ ions by functionalized silver, gold nanoparticles was studied. All the relative studies are outline as follows:

1. A highly sensitive SERS platform for the selective trace analysis of As³⁺ ions was reported based on glutathione (GSH)/4-mercaptopyridine (4-MPY) modified silver nanoparticles (AgNPs). Here, GSH conjugated on the surface of AgNPs for specifical binding with As³⁺ ions in aqueous solution through As-O linkage and 4-MPY was used as a Raman reporter. When As³⁺ ions were added to the system, the binding of As³⁺ with GSH resulted in the aggregation of AgNPs, and excellent Raman signal of 4-MPY reporters was obtained which can reflect the concentration of As³⁺ indirectly. Under optimal assay conditions, the limit of detection (LOD) was estimated to be as low as 0.76ppb which is lower than the WHO defined limit (10ppb), and an excellent linear range of 4-300ppb was obtained. The practical application had been carried out for determination of As³⁺ in real water samples.

2. A rapid and highly reproducible trace analysis technique for determining As³⁺ ions in a polydimethylsiloxane (PDMS) microfluidic sensor was investigated using confocal SERS. Aqueous samples of As³⁺ ions and GSH/4-MPY functionalized AgNPs were introduced into a microfluidic channel fabricated designedly for efficient mixing. The proposed method has been applied satisfactorily to the determination of As³⁺ ions in water. The LOD was estimated to be as low as 3.28ppb, and an excellent linear range of 10-300ppb was obtained.

3. A simple, cost-effective colorimetric sensor for the detection of Ag⁺ using 2-(6-Amino-purin-9-yl)-ethanethiol (A-SH) functionalized gold nanoparticles was developed. The A-SH ligands that we synthesized can easily be coupled to the surface of AuNPs through the Au-S bond and can recognize Ag⁺ by forming an N-Ag-N bond with strong affinity. The presence of Ag⁺ can be monitored by colorimetric response of gold nanoparticles. The detection of Ag⁺ could be realized after measuring the UV-Vis spectra with a detection limit of 2.6×10^-6mol/L, and a linear range of 8.0×10^-6~1.0×10^-4mol/L.