【作者】 王建萍；

【导师】 张忠平；

【作者基本信息】 中国科学技术大学 ， 无机化学， 2015， 博士

【摘要】 伴随现代纳米科技的发展和激光技术的进步,表面增强拉曼光谱(surface-enhanced Raman spectroscopy, SERS)如雨后春笋快速发展,SERS能够检测位于或者接近等离子结构(主要是金银等贵金属)表面的分子,从而极大拓宽了常规拉曼光谱的应用。SERS具有检测灵敏度高、快速、谱峰窄能够实现多组分同时检测以及指纹光谱特性等优势,被广泛应用于爆炸物检测,环境监测以及生物成像等领域。近年来,随着材料科学的发展,基底材料也从单一的贵金属纳米粒子溶胶逐渐发展到兼具SERS和荧光、磁性、光催化等与一体的复合结构材料。为了提高SERS检测技术的普适性,要求SERS基底要具有良好的稳定性、重现性以及对基底表面进行理性修饰等。总而言之,针对不同需要理性设计SERS基底材料和对基底进行理性修饰是SERS检测技术的灵魂。本文制备几种以贵金属材料为基础的SERS增强基底,并且对其进行理性修饰,将其应用到爆炸物检测、癌细胞诊断等领域。主要研究内容如下：1.以银纳米粒子溶胶作为“墨水”,利用喷墨打印机将银纳米粒子打印到试纸上得到银纳米粒子试纸,这是一种简单、经济的制备大面积的SERS基底的方法。将银纳米粒子一层一层的打印到滤膜上面,实现了银纳米粒子在试纸上面的高度规则的覆盖。打印的银纳米粒子试纸收集目标分子以后,试纸上面的不同区域的SERS信号强度几乎一样,证明了这样制备的纸质传感器是很规则的。另外一个方面来说,通过调整打印层数,能够调整表面等离子体吸收的性质以便达到最大的拉曼增强效果。在银纳米粒子试纸上面修饰对巯基苯胺(PABT),修饰PABT的目的有两个,一是通过PABT和三硝基甲苯(TNT)之间的电荷转移反应可以有效地收集空气中漂浮的TNT的分子,二是利用PABT和TNT之间相互作用导致的多重的光谱共振可以巨大的增强PABT的拉曼光谱。于是建立一种拉曼开关的概念：通过PABT拉曼光谱强度的变化来间接反应TNT的含量,实现对TNT的检测。在近红外激光的辅助下还可以实现一种类似于警犬鼻子“闻”那样的方式,检测在各种背景介质例如衣服、皮革、信封、土壤中残留的痕量爆炸物。2.采用自组装的策略制备得到超薄g-C3N4和银包金纳米粒子的复合结构,即在g-C3N4表面修饰阳离子聚合物聚乙烯亚胺(PEI),然后利用静电吸附实现银包金纳米粒子在片子上的组装。这种策略的优势在于复合结构形貌可控、纳米粒子的负载率可调。对于单纯的银包金纳米粒子,因为g-C3N4片子较大的比表面积和π-π*相互作用等能够对目标分子有效吸附,故复合结构具有很强的SERS增强能力。最后,将叶酸分子物理吸附在上述复合结构上,让叶酸充当靶向分子和信号分子的双重角色,利用叶酸与癌细胞表面叶酸受体的特异性作用就可以实现对癌细胞的有效识别。3.先利用“种子生长法”制备四氧化三铁与金纳米粒子哑铃状的异质结构,然后在异质结构中金纳米粒子表面继续生成一层银壳,最后得到了四氧化三铁与银包金纳米粒子的哑铃状异质结构。通过调控金纳米粒子“种子”和前驱体油酸铁的比例,能够实现复合结构从哑铃状结构到核壳结构的演变。上述哑铃状结构既有超顺磁性又具有SERS活性,可以被带有不同功能基团的分子修饰,是一种非常有前景的基底材料。更多还原

【Abstract】 With the development of modern nanometer technology and laser technology, surface enhanced Raman spectroscopy (surface-enhanced Raman spectroscopy, SERS) has been developed rapidly like bamboo shoots after a spring rain. SERS can detect molecules that on or near the surface of plasmonic nanostructures (noble metals such as gold and silver), and it greatly extends the role of standard Raman spectroscopy. SERS has high sensitivity, rapid detection, spectral narrow that can achieve multicomponent determination and fingerprint spectrum characteristics and so on, is widely used in explosives detection, environmental monitoring and biological imaging and other fields. With the development of material science, substrate materials from noble metal nanoparticles sol gradually developed to composite structures, for example, SERS and fluorescent, magnetic, and optical catalytic. In order to improve the universal detection of SERS technique, the substrates need to have good stability, reproducibility, the affinity between molecules and the surface of substrate through rational modification. To make a long story short, the rational design of SERS substrates according to the different needs and the substrates are rationally modified are the soul of SERS detection technology. In this paper, several kinds of noble metal materials were used as SERS substrates and rationally modified them, at last they were applied to detect explosives, the diagnosis of cancer cells and so on. The main research contents are as follows:1. The inkjet printing of AgNPs colloid as ink on cellulose paper is highly simple for the fabrication of large-area SERS substrates. The increment of layer-by-layer printing achieves the highly uniform coverage of AgNPs on the paper. The differences on the various districts of paper for analyte collection and SERS effect are completely eliminated. On the other hand, the change of layer numbers can adjust the surface plasmon properties of aggregating nanoparticles to maximize the SERS response.The layer-by-layer printed AgNPs paper was modified with p-aminobenzenethiol (PABT) for efficiently collecting airborne trinitrotoluene (TNT) via a charge-transfer reaction and for greatly enhancing the Raman scattering of PABT by multiple spectral resonances. Thus, a Raman switch concept by the Raman readout of PABT for the detection of TNT was proposed:The Raman spectrum intensity of PABT can indirectly reflect the content of TNT. Using a beam of near-infrared low-energy laser, inkjet-printed silver nanoparticle paper sensor can be used to detect of explosive particulate residues in various matrices using an approach similar to the olfactory system.2. The ultrathin g-C3N4/ Au@Ag nanoparticle hybrids were fabricated according to a self-assembly procedure. The surface of g-C3N4 modified with cationic polymer polyethyleneimine (PEI) to anchor the Au@AgNPs through electrostatic adsorption. Self-assembly is an ordinary method to fabricate hybrids in which the loading ratio and the morphology of the nanoparticles are tunable. In contrast to Au@AgNPs, the hybrids show stronger SERS activity owing to the large specific surface area and π-π* interaction. Finally, the folic acid molecules physically adsorbed on the hybrids as targeting ligand with folic acid receptor on cancer cells to for cancer cell diagnosis.3. Using the seed growth method to fabricate Fe3O4/Au nanohybrids, and then continue to generate a layer of silver on the gold nanoparticle to form Fe3O4-Au@Ag dumbbell-shaped nanohybrids. The Fe3O4/Au nanohybrids could be finely tuned from heterodimer nanoparticles to core-shell nanoparticles, by controlling the ratio of gold nanoparticles "seed" and iron oleate. The dumbbell nanohybrids are both superparamagnetic and SERS activity, and then could be modified with different molecules to be a promising substrate material.更多还原