Zhang Jian, Fu Yi, Chowdhury Mustafa H, Lakowicz Joseph R
Center for Fluorescence Spectroscopy, University of Maryland School of Medicine, Department of Biochemistry and Molecular Biology, 725 West Lombard Street, Baltimore, Maryland 21201, USA.
Nano Lett. 2007 Jul;7(7):2101-7. doi: 10.1021/nl071084d. Epub 2007 Jun 20.
We prepared silver particle dimers with single Cy5 molecules localized between coupled metal particles. The silver particles with a 20 nm diameter were chemically bound with single-stranded oligonucleotides. The dimers were formed by hybridization with double-length single-stranded oligonucleotides that contained single Cy5 molecules. The image analysis revealed that the single-molecule fluorescence was enhanced 7-fold on the metal monomer and 13-fold on the metal dimer relative to the free Cy5-labeled oligonucleotide in the absence of metal. The lifetimes were shortened on the silver monomers and further shortened on the silver dimers, demonstrating the near-field interaction mechanism of fluorophore with the metal substrate. Finite-difference time-domain (FDTD) calculations were employed to study the distribution of electric field near the metal monomer and dimer. The coupling effect of metal particle on the fluorescence enhancement was discussed.
我们制备了银粒子二聚体，其中单个Cy5分子位于耦合的金属粒子之间。直径为20 nm的银粒子与单链寡核苷酸化学键合。二聚体通过与包含单个Cy5分子的双倍长度单链寡核苷酸杂交形成。图像分析表明，相对于无金属时的游离Cy5标记寡核苷酸，单分子荧光在金属单体上增强了7倍，在金属二聚体上增强了13倍。银单体上的荧光寿命缩短，银二聚体上的荧光寿命进一步缩短，这证明了荧光团与金属底物的近场相互作用机制。采用时域有限差分（FDTD）计算来研究金属单体和二聚体附近的电场分布。讨论了金属粒子对荧光增强的耦合效应。
