Silver nanoparticles self assembly as SERS substrates with near single molecule detection limit
Silver nanoparticles self assembly as SERS substrates with near single molecule detection limit
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DOI：
10.1039/b904744a
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发表时间：
2009-01-01
影响因子：
3.3
通讯作者：
Brolo, Alexandre G.
中科院分区：
文献类型：
--
作者：
Fan, Meikun;Brolo, Alexandre G.
通过自下而上的策略制备了检测极限在齐托莫(尼罗蓝A和恶嗪720)范围内的高灵敏SERS底物。以3-巯丙基三甲氧基硅烷(MPTMS)溶胶-凝胶为连接剂，将银纳米颗粒自组装到玻片上。每次沉积银纳米颗粒后，用UV-Vis和AFM对衬底进行表征。结果发现，经过一次沉积后，载玻片表面只有少量分散的纳米银颗粒。随着沉积次数的增加，玻璃表面逐渐被均匀分布的纳米银颗粒所覆盖。以尼罗蓝A和恶嗪720为探针分子，在632.8 nm和785 nm两种激光激发下，研究了不同银纳米粒子沉积次数下衬底的表面增强拉曼散射。在六次沉积纳米银后，观察到最佳的表面增强拉曼光谱。SERS图谱表明，在较低沉积次数(小于3个纳米银沉积)时，衬底表面出现了几个随机分布的SERS“热点”。7个纳米银沉积后，表面增强拉曼散射信号的空间分布服从高斯统计，其相对标准偏差(RSD%)接近19%。此外，在两种激光激发下，样品间表面增强拉曼散射强度的重复性都低于20%。研究还发现，这些衬底可以提供巨大的拉曼信号增强。在最佳条件下，使用632.8 nm激光，估计只有44个探针分子(100倍物镜)的信号仍然可以被探测到。
Highly sensitive SERS substrates with a limit of detection in the zeptomole (for Nile blue A and oxazine 720) range were fabricated through a bottom-up strategy. Ag nanoparticles (Ag NPs) were self-assembled onto glass slides by using 3-mercaptopropyltrimethoxysilane (MPTMS) sol-gel as linker. The substrates were characterized by UV-Vis and AFM after each deposition of Ag NPs. It was found that the glass slide presented just a few Ag NPs aggregates scattered throughout the surface after just one deposition. The glass surface was gradually covered by a homogeneous distribution of Ag NPs aggregates as the deposition number increased. Surface-enhanced Raman scattering (SERS) of the substrates was examined at different numbers of Ag NPs deposition using nile blue A and oxazine 720 as probe molecules and two laser excitations (632.8 nm and 785 nm). Optimum SERS was observed after six depositions of Ag NPs. SERS mapping indicated that at lower deposition numbers (less than 3 Ag NPs depositions) the substrates presented a few SERS "hot-spots'' randomly distributed at the surface. After 7 Ag NPs depositions, spatial distribution of the SERS signal followed a Gaussian statistics, with a percent relative standard deviation (RSD%) of similar to 19%. In addition, the sample-to-sample reproducibility of the SERS intensities under both laser excitations was lower than 20%. It was also found that these substrates can provide giant Raman signal enhancement. At optimum conditions and with a 632.8 nm laser, the signal from an estimated of only similar to 44 probe molecules (100x objective) can still be detected.