Larsson Elin M, Alegret Joan, Käll Mikael, Sutherland Duncan S
Department of Applied Physics, Chalmers University of Technology, S-41296 Göteborg, Sweden.
Nano Lett. 2007 May;7(5):1256-63. doi: 10.1021/nl0701612. Epub 2007 Apr 13.
The optical responses of 75-150 nm diameter gold nanorings to changes in local refractive index have been quantified by near-infrared extinction spectroscopy and compared to DDA calculations and an analytical approach. The "bulk" refractive index sensitivities of gold nanorings are substantially (>5 times) larger than those of nanodisks with similar diameters. Nanorings retain a significantly larger sensitivity than nanodisks at the same spectral position, demonstrating a clear shape dependence that may correlate to a systematic difference in the influence of the dielectric substrate. The nanoring bulk refractive index sensitivity scales linearly with plasmon peak position. The spectral sensitivity to thin films of alkanethiols gave a shift of approximately 5.2 nm/CH2 unit while bulk sensitivities as high as 880 nm/RIU were observed, the highest such reported sensitivities. Both bulk and thin dielectric film sensitivities correlated well with theory. Real-time label-free monitoring of protein binding via molecular recognition was demonstrated.
通过近红外消光光谱法对直径为75 - 150 nm的金纳米环对局部折射率变化的光学响应进行了量化，并与离散偶极近似（DDA）计算和一种分析方法进行了比较。金纳米环的“体”折射率灵敏度比直径相似的纳米盘的灵敏度大得多（>5倍）。在相同光谱位置，纳米环比纳米盘保持显著更大的灵敏度，表明存在明显的形状依赖性，这可能与介电基底影响的系统差异相关。纳米环的体折射率灵敏度与等离子体峰位置呈线性比例关系。对链烷硫醇薄膜的光谱灵敏度给出了约5.2 nm/CH₂单元的位移，同时观察到高达880 nm/RIU的体灵敏度，这是报道的此类最高灵敏度。体灵敏度和薄介电膜灵敏度与理论都有很好的相关性。证明了通过分子识别对蛋白质结合进行实时无标记监测。
