Austrian Institute of Technology, Donau-City-Strasse 1, 1220 Vienna, Austria.
Anal Chem. 2009 Dec 1;81(23):9625-32. doi: 10.1021/ac901662e.
A new biosensor based on surface plasmon-enhanced fluorescence spectroscopy (SPFS), which employs long-range surface plasmons (LRSP) and a photo-cross-linkable carboxymethyl dextran (PCDM) hydrogel binding matrix, is reported. LRSPs are surface plasmon modes that propagate along a thin metallic film with orders of magnitude lower damping compared to regular surface plasmons. Therefore, their excitation provides strong enhancement of the intensity of the electromagnetic field and a greatly increased fluorescence signal measured upon binding of fluorophore-labeled molecules on the sensor surface. In addition, these modes exhibit highly extended evanescent fields penetrating up to micrometers in distance from the metallic sensor surface. Therefore, a PCDM hydrogel with approximately micrometer thickness was anchored on the sensor surface to serve as the binding matrix. We show that this approach provides large binding capacity and allows for the ultrasensitive detection. In a model experiment, the developed biosensor platform was applied for the detection of free prostate specific antigen (f-PSA) in buffer and human serum by using a sandwich immunoassay. The limit of detection at the low femtomolar range was achieved, which is approximately 4 orders of magnitude lower than that for direct detection of f-PSA based on the monitoring of binding-induced refractive index changes.
本文报道了一种基于表面等离子体增强荧光光谱（SPFS）的新型生物传感器，它采用远程表面等离子体（LRSP）和光交联羧甲基葡聚糖（PCDM）水凝胶结合基质。LRSP 是沿着薄金属膜传播的表面等离子体模式，与常规表面等离子体相比，其阻尼低几个数量级。因此，它们的激发提供了电磁场强度的强烈增强，并大大增加了在传感器表面结合荧光标记分子后测量的荧光信号。此外，这些模式表现出高度扩展的消逝场，从金属传感器表面穿透长达数微米。因此，在传感器表面锚定了约几微米厚的 PCDM 水凝胶作为结合基质。我们表明，这种方法提供了大的结合容量，并允许超灵敏的检测。在模型实验中，通过使用夹心免疫测定法，开发的生物传感器平台用于在缓冲液和人血清中检测游离前列腺特异性抗原（f-PSA）。在低飞摩尔范围内达到了检测限，这比基于监测结合诱导折射率变化的直接检测 f-PSA 的检测限低约 4 个数量级。
