构建银包金纳米星SERS基底并用于6-硫代鸟嘌呤的检测

发布时间：2018-12-21 21:28

【摘要】：表面增强拉曼技术(Surface-enhanced Raman spectroscopy,SERS)作为一种超灵敏分析技术,具有快速、无损、不易淬灭以及水的干扰小等特点,在化学分析、生物诊断、以及环境监测等领域收到了极大的关注。为获取高质SERS信号,需要使用具有高度灵敏性、均一性和重现性的SERS基底,基于贵金属(Au、Ag)的微纳米级结构由于具有优秀的SERS性能以及易于合成等优势被广泛用于高效SERS基底的构建。金纳米星由于其表面尖锐枝角的存在,已被证明具有比球状金纳米颗粒更好的SERS活性。此外,基于金银双金属的纳米复合材料能够有效结合单金属纳米材料优良特性,也已经证明能够构建高SERS活性基底。本论文的工作主要是通过二次种子介导生长法,将新制金纳米星材料作为生长核,在其表面沉积银层,继续生长得到银包金纳米星材料。利用液滴蒸发自组装法将所得银包金纳米星材料致密组装在SMCSL超疏水层表面,制得含有高密度热点分布的AuNS@Ag/SMCSL SERS基底,并利用该基底优异的SERS检测能力实现了人工尿液中6-TG的超灵敏检测。具体工作内容如下:1.采用二次种子介导生长法成功制备了一种银包金纳米星复合材料,并通过控制加入AgNO3溶液的浓度来调控金纳米星表面的银沉积量。分别利用透射电子显微镜(TEM)、能谱仪(EDS)、X射线粉末衍射(XRD)、扫描电子显微镜(SEM)等手段对产物的组成和微观结构进行了表征。以尼罗蓝A为信号分子,对所制备AuNS@Ag的SERS性能进行了评估。结果表明:Ag的沉积明显提高了AuNS@Ag的SERS性能,当加入AgNO3浓度为5 mM时,AuNS@Ag具有最佳的SERS性能。2.基于液滴蒸发自组装技术将已制得的AuNS@Ag纳米颗粒组装在SMCSL膜表面,制得含有高密度热点的SERS基底。扫描电镜图和Raman图证明星形纳米颗粒致密组装在SMCSL表面,产生高密度分布的热点。已制得的AuNS@Ag/SMCSL基底展现相比AuNPs/SMCSL基底更高的SERS增强效果。此外,SERS基底对NBA的检测浓度可降低至10-12M。模拟电场分布的结果证明,基于枝角状AuNS@Ag纳米颗粒的SERS基底具有更高的SERS增强能力。通过对实际分子邻苯二胺和血红蛋白的SERS检测,证明该基底在痕量分析检测领域具有很好的应用前景。3.基于前期实验制得的AuNS@Ag/SMCSL高效SERS基底,实现了不同环境中6-TG分子的超灵敏检测。实验将不同的6-TG溶液液滴直接滴在基底表面,并将AuNS@Ag聚集物完全包裹,达到浸泡的效果。利用SMCSL超疏水性质能够将6-TG分子有效富集到SERS基底表面,从而大幅降低6-TG的浓度检测限。通过检测不同pH环境中的6-TG,可观察pH对6-TG的SERS信号强度的影响。通过对不同共存干扰物质环境中的6-TG进行SERS检测,证明SERS检测技术对6-TG具有高度选择性。将所制得的SERS基底用于人工尿液环境中6-TG的检测,分析了 SERS信号与6-TG浓度的关系,并确定了 6-TG的检测浓度可降低至10-9 M。
[Abstract]:Surface enhanced Raman technique (Surface-enhanced Raman spectroscopy,SERS), as a hypersensitive analysis technique, has the advantages of fast, nondestructive, non-quenched and small water interference, etc., in chemical analysis, biological diagnosis, and so on. And environmental monitoring and other areas have received great attention. In order to obtain high quality SERS signals, a highly sensitive, uniform and reproducible SERS substrate based on precious metals (Au,) is needed. Ag) microstructures have been widely used in the construction of highly efficient SERS substrates due to their excellent SERS properties and easy synthesis. Gold nanoparticles have been proved to have better SERS activity than spherical gold nanoparticles due to the existence of sharp branching angles on the surface. In addition, the gold and silver bimetallic nanocomposites can effectively combine the excellent properties of monometallic nanomaterials and have been proved to be able to construct high SERS active substrates. The main work of this thesis is to use the new gold nanoparticles as the growth nucleus and deposit silver layer on the surface through the secondary seeding method to obtain the silver coated gold nanosars. The silver coated gold nanoparticles were assembled on the surface of SMCSL superhydrophobic layer by droplet evaporation self-assembly method, and the AuNS@Ag/SMCSL SERS substrate containing high density hot spots was prepared. The hypersensitive detection of 6-TG in artificial urine was realized by using the excellent SERS detection ability of the substrate. The specific contents of the work are as follows: 1. A silver clad gold nanocomposite was successfully prepared by secondary seeded growth method and the amount of silver deposition on the surface of gold nanocrystals was controlled by controlling the concentration of AgNO3 solution. The composition and microstructure of the product were characterized by transmission electron microscope (TEM),) (TEM), spectrometer (EDS), X ray powder diffraction (XRD), scanning electron microscope (SEM). The SERS properties of AuNS@Ag were evaluated using Nile blue A as signal molecule. The results show that the deposition of Ag improves the SERS performance of AuNS@Ag. When the concentration of AgNO3 is 5 mM, AuNS@Ag has the best SERS performance. The prepared AuNS@Ag nanoparticles were assembled on the surface of SMCSL films based on droplet evaporation self-assembly technology to prepare SERS substrates with high density hot spots. Scanning electron microscopy (SEM) and Raman images show that the starlike nanoparticles are tightly assembled on the surface of SMCSL, resulting in hot spots of high density distribution. The prepared AuNS@Ag/SMCSL substrate exhibits higher SERS enhancement than the AuNPs/SMCSL substrate. In addition, the detection concentration of NBA on SERS substrate can be reduced to 10-12M. The simulated electric field distribution shows that the SERS substrate based on dendritic AuNS@Ag nanoparticles has higher SERS enhancement ability. The SERS detection of the actual molecule o-phenylenediamine and hemoglobin shows that the substrate has a good application prospect in the field of trace analysis. The hypersensitive detection of 6-TG molecules in different environments was realized based on the AuNS@Ag/SMCSL SERS substrate prepared by previous experiments. In the experiment, the droplets of different 6-TG solutions were dripped directly on the substrate surface, and the AuNS@Ag aggregates were completely encapsulated to achieve the effect of soaking. By using the superhydrophobic properties of SMCSL, 6-TG molecules can be effectively enriched on the surface of SERS substrate, thus greatly reducing the detection limit of 6-TG concentration. The influence of pH on SERS signal intensity of 6-TG can be observed by detecting 6-TG in different pH environment. Through the SERS detection of 6-TG in the environment of different interference substances, it is proved that the SERS detection technology is highly selective to 6-TG. The SERS substrate was used to detect 6-TG in artificial urine environment. The relationship between the SERS signal and the concentration of 6-TG was analyzed, and the detection concentration of 6-TG could be reduced to 10-9 M.
【学位授予单位】：东南大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O657.37

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