Trnavsky Michal, Enderlein Joerg, Ruckstuhl Thomas, McDonagh Colette, MacCraith Brian D
Dublin City University, Biomedical Diagnostics Institute, National Centre for Sensor Research, School of Physical Sciences, Glasnevin, Dublin 9, Ireland.
J Biomed Opt. 2008 Sep-Oct;13(5):054021. doi: 10.1117/1.2978067.
Surface plasmon-coupled emission (SPCE) is a phenomenon whereby the light emitted from a fluorescent molecule can couple into the surface plasmon of an adjacent metal layer, resulting in highly directional emission in the region of the surface plasmon resonance (SPR) angle. In addition to high directionality of emission, SPCE has the added advantage of surface selectivity in that the coupling diminishes with increasing distance from the surface. This effect can be exploited in bioassays whereby a fluorescing background from the sample can be suppressed. We have investigated, both theoretically and experimentally, the SPCE effect for a Cy5-spacer-Ag layer system. Both the angular dependence of emission and the dependence of SPCE emission intensity on Cy5-metal separation were investigated. It is demonstrated that SPCE leads to lower total fluorescence signal than that obtained in the absence of a metal layer. This is the first experimental verification of the reduction in SPCE intensity compared to the metal-free case. Our results are in a good agreement with theoretical models. The validation of the theoretical model provides a basis for optimizing biosensor platform performance, particularly in the context of the advantages offered by SPCE of highly directional emission and surface selectivity.
表面等离子体耦合发射（SPCE）是一种现象，即荧光分子发射的光可以耦合到相邻金属层的表面等离子体中，从而在表面等离子体共振（SPR）角区域产生高度定向发射。除了发射的高方向性外，SPCE还具有表面选择性的额外优势，即随着与表面距离的增加，耦合会减弱。这种效应可用于生物测定，从而抑制样品中的荧光背景。我们在理论和实验上都研究了Cy5-间隔物-银层系统的SPCE效应。研究了发射的角度依赖性以及SPCE发射强度对Cy5-金属间距的依赖性。结果表明，与没有金属层时相比，SPCE导致的总荧光信号更低。这是与无金属情况相比SPCE强度降低的首次实验验证。我们的结果与理论模型吻合良好。理论模型的验证为优化生物传感器平台性能提供了基础，特别是考虑到SPCE具有高度定向发射和表面选择性的优势。
