A SERS-active system based on silver nanoparticles tethered to a deposited silver film
A SERS-active system based on silver nanoparticles tethered to a deposited silver film
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DOI：
10.1021/jp055243y
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发表时间：
2006-07-20
影响因子：
3.3
通讯作者：
Moskovits, M.
中科院分区：
文献类型：
--
作者：
Anderson, D. J.;Moskovits, M.
通过将新沉积的银膜（制造成尽可能不粗糙）暴露于含有1-癸二硫醇（m）和1，9-壬二硫醇（d）的混合物的溶液中，然后使胶体银纳米颗粒与表面相互作用，产生一系列SERS活性纳米结构。发现银纳米颗粒仅结合到由具有非零浓度的二硫醇的溶液制备的膜上，这意味着纳米颗粒通过二硫醇束缚到银表面，其中一个硫醇盐基团结合到纳米颗粒上，另一个结合到银膜上。即使从样品中观察到强烈的Sers光谱，其中m/d浓度比是如此之大，以至于仅在近似8 +/-3纳米颗粒附近的吸附分子被衍射极限聚焦激光束照射。在如此高的稀释度下，驻留在与类似于8个纳米颗粒相关的Sers“热点”中的分子（编号最多类似于330个）主要由m组成（当然，对于每个纳米颗粒，热点中的至少一个分子必须是d以充当连接体）。Sers光谱证实了这一点。提出了一个分析，占的事实，即作为浓度比的m/d的增加，与属于m的频带的Sers强度首先增加到最大值，然后减少。这里提出的纳米颗粒-金属膜系统是更一般范围的SERS活性传感平台的简单实施例，其中分子系链用于产生Sers热点，该热点（尽管是纳米尺寸的）足够大以容纳本身不能作为连接体的分析物分子，其随后通过Sers在少分子水平上检测。
A series of SERS-active nanostructures were produced by exposing a freshly deposited silver film ( fabricated to be as free from roughness as practicable) to a solution containing a mixture of 1-decanethiol (m) and 1,9-nonanedithiol (d) of varying concentrations of m to d, then allowing colloidal silver nanoparticles to interact with the surface. Silver nanoparticles were found to bind exclusively to films which were prepared from solutions with a nonzero concentration of the dithiol implying that the nanoparticles were tethered to the silver surface by the dithiol with one of the thiolate groups bound to the nanoparticle and the other to the silver film. Intense SERS spectra were observed even from samples in which the m/d concentration ratio was so large that the adsorbed molecules in the vicinity of only similar to 8 +/- 3 nanoparticles were illuminated by the diffraction-limited focused laser beam. At such high dilution, the molecules (numbering at most similar to 330) residing in the SERS "hot spots" associated with the similar to 8 nanoparticles consisted primarily of m (although, of course, for each nanoparticle, at least one molecule in the hot spot had to be d to serve as the linker). This was corroborated by the SERS spectra. An analysis is presented, which accounts for the fact that as the concentration ratio of m/d increases, the SERS intensity associated with bands belonging to m first increases to a maximum then decreases. The nanoparticle-metal film system presented here is a simple embodiment of a more general range of SERS-active sensing platforms in which a molecular tether is used to create a SERS hot spot that (although nanosized) is large enough to accommodate analyte molecules that cannot themselves function as linkers, which are subsequently detected by SERS at the few-molecule level.