Institute for Frontier Medical Sciences, Kyoto University, 53 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507, Japan.
Anal Biochem. 2012 Feb 15;421(2):632-9. doi: 10.1016/j.ab.2011.12.008. Epub 2011 Dec 9.
Surface plasmon field-enhanced fluorescence spectroscopy (SPFS) combines enhanced field platform and fluorescence detection. Its advantages are the strong intensity of the electromagnetic field and the high signal/noise (S/N) ratio due to the localized evanescent field at the water/metal interface. However, the energy transfer from the fluorophore to the metal surface diminishes the fluorescence intensity, and this reduces the sensitivity. In this study, we tested whether polystyrene (PSt) could act as a dielectric layer to suppress the energy transfer from the fluorophore to the metal surface. We hypothesized that this would improve the sensitivity of SPFS-based immunoassays. We used α-fetoprotein (AFP) as a model tumor biomarker in the sandwich-type immunoassay. We determined the relationship between fluorescent signal intensity and PSt layer thickness and compared this to theoretical predictions. We found that the fluorescence signal increased by optimally controlling the thickness of the PSt layer. Our results indicated that the SPFS-based immunoassay is a promising clinical diagnostic tool for quantitatively determining the concentrations of low-level biomarkers in blood samples.
表面等离激元场增强荧光光谱（SPFS）结合了增强场平台和荧光检测。由于在水/金属界面处存在消逝场，该技术具有电磁场强度高和信号/噪声（S/N）比高的优点。然而，荧光团向金属表面的能量转移会降低荧光强度，从而降低了灵敏度。在本研究中，我们测试了聚苯乙烯（PSt）是否可以作为介电层来抑制荧光团向金属表面的能量转移。我们假设这将提高基于 SPFS 的免疫分析的灵敏度。我们使用甲胎蛋白（AFP）作为夹心型免疫分析中的模型肿瘤生物标志物。我们确定了荧光信号强度与 PSt 层厚度之间的关系，并与理论预测进行了比较。我们发现通过优化控制 PSt 层的厚度可以增加荧光信号。我们的结果表明，基于 SPFS 的免疫分析是一种有前途的临床诊断工具，可用于定量确定血液样本中低水平生物标志物的浓度。
