【作者】 崔颜；

【导师】 顾仁敖； 田中群；

【作者基本信息】 苏州大学 ， 物理化学， 2006， 硕士

【摘要】 表面增强免疫分析(SERIA)是充分利用表面增强拉曼光谱(SERS)的高灵敏度和光谱选择性,结合抗体抗原的特性吸附作用所发展出来的一种新的检测技术。在以SERS为检测手段进行免疫分析过程中,SERS光谱的高选择性,高分辨率是其优于传统红外光谱,荧光光谱的一大关键。而如何提高SERIA的检测灵敏度是其最终能否成为临床检测技术的关键所在。一般情况下,Ag纳米粒子表面的SERS增强因子要比Au纳米粒子高,但Au纳米粒子与Ag相比更具有生物兼容性,而核壳纳米粒子通常具有其单组分纳米粒子所没有的独特性质。因此将Au包裹在Ag纳米粒子表面,形成Ag核Au壳复合纳米粒子,这样一方面可以通过电磁场增强的长程效应,从“借力”角度使其获得比Au更强的SERS增强,另一方面Au壳的亲生物性使Ag核Au壳复合纳米粒子在SERIA中的应用具有可能性。本文通过种子生长法合成了Ag核Au壳复合纳米粒子,研究表明随着Au摩尔分数的增加,Ag纳米粒子表面首先出现一些孔洞,随后孔洞消失。以对巯基苯胺(PATP)和苯硫酚(TP)为标记分子研究Ag核Au壳复合纳米粒子的SERS活性,发现随着Au摩尔分数的增加,其SERS活性呈现先增强后减弱的趋势,最大的增强为Ag纳米粒子表面的10倍。这可能是由于复合纳米粒子表面孔洞产生较强的电磁场增强所引起的。将SERS活性较强的Ag核Au壳复合纳米粒子用抗体和标记分子修饰进行免疫检测,若抗体抗原发生特异性吸附,则可以通过Ag核Au壳复合纳米粒子表面标记分子信号的检测确定待测抗原的种类。Ag核Au壳复合纳米粒子作为一种具有较强SERS活性和生物兼容性的纳米粒子可应用于SERIA研究中。更多还原

【Abstract】 Surface enhanced Raman immunoassay analysis (SERIA) is a new detective technique that combines the advantages of surface enhanced Raman spectroscopy and the immunoassay analysis. However, whether SERIA can be really employed in clinic depends on its detection sensitivity. In previous researches, Au nanoparticles were mainly used as the Raman enhancer for immunoassay due to its biocompatibility and easy preparation, but Au nanoparticles show a lower enhancement in the visible light region in comparison with that of Ag. The motivation of the present study is to prepare the AgcoreAushell bimetallic nanoparticles with unique optical and chemical properties for immunoassay. It is expected that on one hand the Au layers on the nanoparticle surface are biocompatible and on the other hand, the underneath Ag core may provide extra enhancement. In a typical experiment, layered core-shell bimetallic silver-gold nanoparticles were prepared by coating Au layers over Ag seeds using a seed-growth method. With the increase of the Au molar fraction, some pinholes appeared on the nanoparticle surface, which was then coated with a complete Au shell. Correspondingly, the SERS intensity of adsorbed probe molecules (TP and PATP) enhanced first and then weakened, with the maximal intensity being 10 times higher than that on Ag. This unexpected result could be attributed to the presence of some pinholes that act as hot spots for the electromagnetic field enhancement. The SERS active bimetallic nanoparticles were then modified with probe molecules and antibodies to form a reporter-labeled AgcoreAushell nanoparticles and used for immunoassay analysis. Parallel to this, the antibodies were immobilized on a solid substrate for capturing antigens from solution. The captured antigens could then bind the reporter-labeled AgcoreAushell nanoparticles modified with same antibodies, forming a sandwich type complex“capture antibody substrate/antigen/reporter labeled immuno-AgcoreAushell bimetallic nanoparticles”. The binding specificity was successfully demonstrated by the detection of characteristic Raman bands of the probe molecules. This primary study demonstrates that the AgcoreAushell bimetallic nanoparticles labeled by the monoclonal antibodies and SERS probes could be used for immunoassay analysis.更多还原