Ekgasit Sanong, Yu Fang, Knoll Wolfgang
Sensor Research Unit, Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand.
Langmuir. 2005 Apr 26;21(9):4077-82. doi: 10.1021/la047775w.
Movement of a fluorophore-labeled antibody on the surface of a self-assembled monolayer (SAM) was observed by surface plasmon resonance and surface-plasmon field-enhanced fluorescence spectroscopy (SPFS). At an extremely low surface coverage, the antibody lies close to the biotin-functionalized SAM surface. As additional nonlabeled antibodies were bound, the fluorophore-labeled antibody was displaced away from the SAM surface (and thus the gold surface) due to the constraint imposed by the neighboring nonlabeled antibody. A greater SPFS fluorescence signal was observed due to the weaker fluorescence quenching at large distances from the gold surface. The magnitude of the displacement is proportional to the available biotin binding sites on the sensor surface. The displacement is theoretically explained on the basis of the relationship between the fluorescence intensity and the evanescent field amplitude within the dielectric medium.
通过表面等离子体共振和表面等离子体场增强荧光光谱（SPFS）观察了荧光团标记抗体在自组装单分子层（SAM）表面的移动。在极低的表面覆盖率下，抗体靠近生物素功能化的SAM表面。当额外的未标记抗体结合时，由于相邻未标记抗体施加的限制，荧光团标记的抗体从SAM表面（进而从金表面）被取代。由于在距金表面较大距离处荧光猝灭较弱，观察到更大的SPFS荧光信号。位移的大小与传感器表面可用的生物素结合位点成正比。基于介电介质内荧光强度与倏逝场振幅之间的关系，从理论上解释了这种位移。
