Fluorescence enhancement on silver nanoplates at the single- and sub-nanoparticle level
Fluorescence enhancement on silver nanoplates at the single- and sub-nanoparticle level
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单纳米粒子和亚纳米粒子水平上银纳米片的荧光增强
DOI：
10.1039/c5nr06146f
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发表时间：
2015-01-01
期刊：
影响因子：
6.7
通讯作者：
Zhou, Xiaochun
中科院分区：
文献类型：
--
作者：
Shen, Yangbin;He, Ting;Zhou, Xiaochun
当荧光分子靠近金属纳米粒子时，荧光分子的荧光强度可以被强烈增强。因此，荧光增强技术在生物和医学领域有着广泛的应用。如果我们打算开发更好的材料来提高这种增强，就有必要了解这种吸引效应的机制。在本文中，我们用超分辨显微镜直接成像了银纳米片上不同的荧光增强模式。研究表明，银纳米片的边缘或尖端通常比中间部分具有更高的荧光增强能力。荧光增强的空间分布很大程度上取决于银纳米片的尺寸以及银纳米片与入射光的夹角。上述实验结果与局域表面等离子体共振（LSPR）理论模拟的电场基本一致，但仍存在一些不规则性。我们还发现，小银纳米片上的荧光增强主要是由于面内偶极等离子激元共振，而大银纳米片上的荧光增强主要是由于面内四极等离子激元共振。此外，大平板的平面内四极共振比平面内偶极等离子体共振具有更高的荧光信号增强能力。本研究为单纳米和亚纳米水平的荧光增强提供了许多有价值的见解，并将有助于开发更好的相关材料。
The fluorescence intensity of a fluorescent molecule can be strongly enhanced when the molecule is near a metal nanoparticle. Hence, fluorescence enhancement has a lot of applications in the fields of biology and medical science. It is necessary to understand the mechanism for such an attractive effect, if we intend to develop better materials to improve the enhancement. In this paper, we directly image the diverse patterns of fluorescence enhancement on single Ag nanoplates by super-resolution microscopy. The research reveals that the edges or tips of the Ag nanoplate usually show a much higher ability of fluorescence enhancement than the mid part. The spatial distribution of fluorescence enhancement strongly depends on the size of the Ag nanoplate as well as the angle between the Ag nanoplate and the incident light. The experimental results above are essentially consistent with the simulated electric field by the theory of localized surface plasmon resonance (LSPR), but some irregularities still exist. We also find that fluorescence enhancement on small Ag nanoplates is mainly due to in-plane dipole plasmon resonance, while the enhancement on large Ag nanoplates is mainly due to in-plane quadrupole plasmon resonance. Furthermore, in-plane quadrupole resonance of large plates has a higher ability to enhance the fluorescence signal than the in-plane dipole plasmon resonance. This research provides many valuable insights into the fluorescence enhancement at the single-and sub-nanoparticle level, and will be very helpful in developing better relevant materials.