Howard Hughes Medical Institute, Department of Chemistry, University of California, Berkeley, California 94720, USA.
Nano Lett. 2012 Mar 14;12(3):1717-21. doi: 10.1021/nl300294b. Epub 2012 Feb 29.
Coupling of the localized surface plasmons between two closely apposed gold nanoparticles (nanoantenna) can cause strong enhancements of fluorescence or Raman signal intensity from molecules in the plasmonic "hot-spot". Harnessing these properties for practical applications is challenging due to the need to fabricate gold particle arrays with well-defined nanometer spacing and a means of delivering functional molecules to the hot-spot. We report fabrication of billions of plasmon-coupled nanostructures on a single substrate by a combination of colloid lithography and plasma processing. Controlled spacing of the nanoantenna gaps is achieved by taking advantage of the fact that polystyrene particles melt together at their contact point during plasma processing. The resulting polymer thread shadows a gap of well-defined spacing between each pair of gold triangles in the final array. Confocal surface-enhanced Raman spectroscopy imaging confirms the array is functionally uniform. Furthermore, a fully intact supported membrane can be formed on the intervening substrate by vesicle fusion. Trajectories of freely diffusing individual proteins are traced as they sequentially pass through, and are enhanced by, multiple gaps. The nanoantenna array thus enables enhanced observation of a fluid membrane system without static entrapment of the molecules.
两个紧密相邻的金纳米粒子（纳米天线）之间的局域表面等离激元耦合会导致等离子体“热点”中分子的荧光或拉曼信号强度的强烈增强。由于需要制造具有良好定义的纳米级间距的金颗粒阵列以及将功能分子递送至热点的方法，因此利用这些特性来实现实际应用具有挑战性。我们通过胶体光刻和等离子体处理的组合，在单个衬底上制造了数十亿个等离子体耦合的纳米结构。纳米天线间隙的受控间距是通过利用在等离子体处理过程中聚苯乙烯颗粒在其接触点处熔化的事实来实现的。由此产生的聚合物线在最终阵列中每对金三角形之间的间隙处形成了明确的阴影。共焦表面增强拉曼光谱成像证实了该阵列的功能均匀性。此外，通过囊泡融合可以在中间衬底上形成完整的、未受破坏的支撑膜。当单个蛋白质自由扩散轨迹通过多个间隙时，它们会被跟踪并被增强。因此，纳米天线阵列可以在不静态捕获分子的情况下增强对流体膜系统的观察。
