Kim Kwan, Park Hyoung Kun, Kim Nam Hoon
Laboratory of Intelligent Interfaces, School of Chemistry, Seoul National University, Seoul 151-742, Korea.
Langmuir. 2006 Mar 28;22(7):3421-7. doi: 10.1021/la052912q.
In this study, we demonstrate that 2-microm-sized Ag (microAg) powders can be used as a core material for constructing molecular sensing/recognition units operating via surface-enhanced Raman scattering (SERS). This is possible because microAg powders are very efficient substrates for both the infrared and Raman-spectroscopic characterization of molecular adsorbates prepared in a similar manner on silver surfaces; we can obtain an infrared spectrum of organic molecules adsorbed on microAg particles with a very high signal-to-noise ratio by diffuse reflectance infrared Fourier transform spectroscopy (DRIFT), and the Raman spectrum of organic monolayers on powdered silver is an SERS spectrum. The agglomeration of microAg particles in a highly concentrated buffer solution could be prevented by the layer-by-layer deposition of cationic and anionic polyelectrolytes such as poly(allylamine hydrochloride) (PAH) and poly(acrylic acid) (PAA). In fact, prior to depositing PAA and PAH, 4-aminobenzenethiol (4-ABT) was assembled on the surfaces of the microAg particles as SERS markers. Because of the presence of amine groups of 4-ABT, PAA could be readily deposited on the microAg particles. On the other hand, the outermost PAA layer could also be derivatized with biotin-derivatized poly(L-lysine). The nonspecific interaction of poly(L-lysine) with proteins could be suppressed by grafting poly(ethylene glycol) into the biotin-derivatized poly(L-lysine) molecules. On the basis of the nature of the SERS peaks of 4-ABT, it was confirmed that these biotinylated microAg powders were effective in selectively recognizing the streptavidin arrays. Because a number of different molecules can be used as SERS-marker molecules, such as probable 4-ABT, commercially available microAg powders must be a prospective material in molecular sensing/recognition, particularly via SERS.
在本研究中，我们证明了2微米大小的银（微银）粉末可作为构建通过表面增强拉曼散射（SERS）运行的分子传感/识别单元的核心材料。这是可行的，因为微银粉末对于以类似方式在银表面制备的分子吸附物的红外和拉曼光谱表征而言是非常有效的基底；我们可以通过漫反射红外傅里叶变换光谱（DRIFT）获得吸附在微银颗粒上的有机分子的具有非常高信噪比的红外光谱，并且粉末状银上有机单层的拉曼光谱就是一种SERS光谱。通过阳离子和阴离子聚电解质如聚（烯丙胺盐酸盐）（PAH）和聚（丙烯酸）（PAA）的逐层沉积，可以防止微银颗粒在高浓度缓冲溶液中的团聚。实际上，在沉积PAA和PAH之前，4-氨基苯硫醇（4-ABT）作为SERS标记物组装在微银颗粒表面。由于4-ABT存在胺基，PAA可以很容易地沉积在微银颗粒上。另一方面，可以用生物素衍生化的聚（L-赖氨酸）对最外层的PAA层进行衍生化。通过将聚（乙二醇）接枝到生物素衍生化的聚（L-赖氨酸）分子中，可以抑制聚（L-赖氨酸）与蛋白质的非特异性相互作用。基于4-ABT的SERS峰的性质，证实了这些生物素化的微银粉末在选择性识别链霉亲和素阵列方面是有效的。因为许多不同的分子可以用作SERS标记分子，例如可能的4-ABT，市售的微银粉末必定是分子传感/识别中的一种有前景的材料，特别是通过SERS。
