具有响应性的功能性贵金属复合纳米粒子的制备及其原位SERS研究

发布时间：2018-07-07 22:03

本文选题：表面增强拉曼散射 + 复合纳米粒子　；参考：《上海师范大学》2017年硕士论文

【摘要】：在最近的几十年里,大量的研究团队制备了各种表面增强拉曼散射(SERS)基底来增强目标分析物的拉曼信号。特别是在可见近红外区有很高等离子活性的银(Ag)和金(Au)纳米结构已经被广泛使用。但是普通的SERS基底由于团聚程度难以控制,导致增强效率不均匀。要克服这些缺点,发展均匀的、结构可控的SERS基底是必需的。因此,本文引入了具有粘附性、反应性、吸附性、还原性、螯合作用、亲水性等特性的聚多巴胺(PDA),以及具有多刺激响应性的聚(N-异丙基丙烯酰胺)(PNIPAAm),结合Ag、Au等贵金属,采用简单有效的方法制备了三种不同的功能性原位SERS基底,实现了对农药,有机染料,有机污染物的原位定性定量检测。具体内容如下:1、利用简单快速的方法,制备了由聚多巴胺(PDA)壳覆盖立方氯化银(AgCl)核的复合材料,该复合材料表面镶嵌银纳米粒子(AgNPs),命名为AgCl/PDA/AgNPs。由此产生的AgCl/PDA/AgNPs可用作原位检测的SERS基底,由于该基底在激光照射下可以产生更多的AgNPs,因此,其SERS活性可以进一步大大改进。4-巯基吡啶(4-Mpy)作为探针分子,增强因子可以达到107。此外,这种SERS基底具有长期稳定性(暗处保存100天之后,SERS活性强度依然可以保持在75%以上)和良好的重现性(相对标准偏差在7.32%)。激光照射AgCl/PDA/AgNPs,原位增强其SERS活性可能有利于其在实用性领域中的灵敏性分析。2、上述复合材料由于表面PDA层的存在而具有反应性,故该复合材料很容易用含巯基的温敏性聚(N-异丙基丙烯酰胺)(PNIPAAm-SH)修饰成为多刺激响应的动态SERS基底。向修饰后的SERS基底(AgCl/PDA/AgNPs@PNIPAAm)体系中加入卤化物盐后不仅可诱导PNIPAAm在室温下发生相转变,还可以富集微量物质,导致待测物SERS信号的进一步增强,故该基底可以实现对有机染料亚甲基蓝(MB)的pM级检测,检测限可以达到1pM。我们的发现可能有助于发展绿色、低成本的SERS基底,用作快速、定量检测微量有机分子。3、利用金纳米粒子(AuNPs)在聚多巴胺粒子(PDA)中的可控合成制备了PDA-Au复合材料,它在拉曼激光、紫外灯或者超声等外界条件刺激下会发生破裂,并且释放出AuNPs@PDA核壳纳米粒子。由于PDA中心负载了大量的AuNPs,所以该复合材料在紫外灯或者拉曼光谱照射下显示出了卓越的光热转换能力,导致PDA-Au可以“遥控爆炸”,快速释放出大量AuNPs@PDA。而且这个释放过程可以通过关闭或重启拉曼激光/紫外灯来实现立即停止或再次启动。此外,利用AuNPs@PDA表面的PDA与PAHs之间存在的π-π相互作用,完成了对水环境中PAHs的定性定量检测。因此,我们已经证明由于PDA-Au NPs具有原位生成新鲜吸附剂、催化剂的能力,所以在水中PAHs的检测方面显示出了优异、持续的性能。
[Abstract]:In recent decades, a large number of research teams have prepared various surface-enhanced Raman scattering (SERS) substrates to enhance the Raman signal of target analytes. Especially silver (Ag) and gold (Au) nanostructures with high plasma activity in the near infrared region have been widely used. However, the common SERS substrate is difficult to control the degree of agglomeration, resulting in uneven enhancement efficiency. To overcome these shortcomings, it is necessary to develop uniformly and structurally controllable SERS substrate. In this paper, PDAs with adhesion, reactivity, adsorbability, reduction, chelation and hydrophilicity were introduced, as well as poly (N-isopropylacrylamide) (PNIPAAm) with multiple stimuli response, and noble metals such as Agna au, etc. Three kinds of functional in situ SERS substrates were prepared by a simple and effective method, and the in situ qualitative and quantitative detection of pesticides, organic dyes and organic pollutants was realized. The main contents are as follows: 1. By using a simple and rapid method, a composite material coated with cubic silver chloride (AgCl) nucleus was prepared. The composite was coated with silver nanoparticles (AgNPs) on the surface of the composite named AgCl / PDA / AgNPs. The resulting AgCl / PDA / AgNPs can be used as SERS substrates for in situ detection. Since the substrate can produce more AgNPs under laser irradiation, its SERS activity can be further improved by using 4-mercaptopyridine (4-Mpy) as a probe molecule, and the enhancement factor can reach 107. In addition, the SERS substrate has long-term stability (the intensity of SERS activity remains above 75% after 100 days of dark storage) and good reproducibility (relative standard deviation is 7.32%). Laser irradiation of AgCl / PDA / AgNPs and in situ enhancement of SERS activity may be beneficial to the sensitivity analysis of AgCl / PDA / AgNPs in the practical field. The above composite materials are reactive because of the existence of PDA layer on the surface. Therefore, it is easy to modify the composite into a dynamic SERS substrate with multiple stimuli response by thermo-sensitive poly (N-isopropylacrylamide) (PNIPAAm-SH) containing sulfhydryl group. Adding halides to the modified SERS substrate can not only induce the phase transition of PNIPAAm at room temperature, but also enrich trace substances, resulting in the further enhancement of SERS signal. Therefore, this substrate can be used to detect methylene blue (MB) with a detection limit of 1 pm. Our findings may contribute to the development of green, low-cost SERS substrates for rapid, quantitative detection of microamounts of organic molecules. PDA-Au composites are prepared by the controllable synthesis of gold nanoparticles (AuNPs) in polydopamine particles (PDA-Au), which are used in Raman lasers. External stimuli such as ultraviolet lamp or ultrasound will rupture and release AuNPs @ PDA core-shell nanoparticles. Because the PDA center is loaded with a large amount of AuNPs, the composite shows excellent photothermal conversion ability under ultraviolet lamp or Raman spectroscopy irradiation, resulting in PDA-Au "remote explosion", rapidly releasing a large number of AuNPs PDAs. And the release process can be stopped or restarted immediately by turning off or restarting the Raman laser / UV lamp. In addition, qualitative and quantitative detection of PAHs in water environment was carried out by the 蟺-蟺 interaction between PDA and PAHs on the surface of AuNPs @ PDA. Therefore, we have demonstrated that PDA-Au NPs have excellent and continuous performance in the detection of PAHs in water because of their ability to produce fresh adsorbents and catalysts in situ.
【学位授予单位】：上海师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB383.1;O657.37

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