Surface-plasmon field-enhanced fluorescence spectroscopy
Surface-plasmon field-enhanced fluorescence spectroscopy
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DOI：
10.1016/s0927-7757(99)00550-6
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发表时间：
2000-10-10
影响因子：
5.2
通讯作者：
Knoll, W
中科院分区：
文献类型：
--
作者：
Liebermann, T;Knoll, W
我们描述了用于传感器应用的表面等离子激元和荧光光谱的组合。流动池中金属/缓冲器界面处的PSP模的共振激发导致光场强度比入射激光有很大的增强：实验上证实了用菲涅耳公式计算的金/水界面光场强度的16倍。这种场增强可以用来提高监测分析物从水相到功能化界面上的识别位置的结合反应的灵敏度，前提是这种界面结构确保结合的(荧光标记的)分析物分子仍然在PSP模式的指数衰减的衰减范围内，然而，也使它们充分远离金属的(接受者)状态，以避免发射的荧光的Forster猝灭。给出了两个例子的定量分析：一个是荧光掺杂胶乳颗粒的结合(在亚单层覆盖)，在其表面还携带生物素部分，以结合到金/缓冲液界面的链霉亲和素层。这里，可以分析荧光强度和层厚度之间的相关性。第二个例子涉及到一个很小的生物素化发色团，它与链霉亲和素层的非常稀疏的结合只导致PSP共振曲线的微小角移，太小而无法检测。然而，荧光强度很容易记录下来，并给出了大约1000个可获得的增强因子的粗略估计。(C)2000 Elsevier Science B.V.保留所有权利。
We describe the combination of surface plasmon- and fluorescence spectroscopy for sensor applications. The resonant excitation of PSP modes at a metal/buffer-interface in a flow cell results in optical field intensities largely enhanced compared to the incoming laser light: a factor of 16, calculated for a Au/water interface by Fresnel formulas was experimentally confirmed. This field enhancement can be used to increase the sensitivity for monitoring binding reactions of an analyte from the aqueous phase to the recognition sites at a functionalized interface, provided this interfacial architecture ensures that the bound (fluorescently labeled) analyte molecules are still within the exponentially decaying evancescent held of the PSP mode, however, also keeping them sufficiently away from the (acceptor states of the) metal to avoid Forster quenching of the emitted fluorescence. A quantitative analysis is given for two examples: one is the binding of fluorescently-doped latex particles, (at sub-monolayer coverage), carrying in addition biotin-moieties at their surface for binding to a streptavidin layer at the Au/buffer interface. Here, a correlation between fluorescence intensity and layer thickness can be analyzed. A second example concerns a small biotinylated chromophore, the very dilute binding of which to the streptavidin layer results in only a minute angular shift of the PSP resonance curve, too small to be detected. The fluorescence intensity, however, is easily recorded and gives a rough estimate of the obtainable enhancement factor of ca. 1000. (C) 2000 Elsevier Science B.V. All rights reserved.