螺旋纳米粒子手性金属膜和表面增强拉曼光谱对映体的识别
Chiral Metafilms and Surface Enhanced Raman Scattering For Enantiomeric Discrimination of Helicoid Nanoparticles
摘要：
手性纳米光子平台提供了一种产生具有增强的不对称性质和强度的近场的方法。它们可以被利用的光学测量，允许对映体的歧视，在检测水平大于6个数量级，比实现与传统的手性敏感的光谱方法的基础上，圆偏振光。利用纳米光子平台进行手性检测的最佳方法是使用光谱方法，该方法提供了由手性物质的存在引起的近场环境变化的局部探针。在这里，我们表明，表面增强拉曼光谱（SERS）是这样的近场环境的本地探针。我们已经用它来实现对映体歧视的手性螺旋纳米粒子沉积在左手和右手的手性超薄膜的对映体。更热的电磁热点被创建为匹配的螺旋面和超薄膜组合（左-左和右-右），而不匹配的组合导致明显更冷的电磁热点。这种大的对映体的热点强度的依赖性，很容易检测到使用SERS与援助的非手性拉曼报告分子。实际上，我们已经使用SERS来区分通过混合手性纳米颗粒和超膜产生的等离子体非对映异构体的不同EM环境。这项工作表明，通过将手性纳米光子平台与已建立的SERS策略相结合，可以开辟超灵敏手性检测的新途径。
英文摘要：
Chiral nanophotonic platforms provide a means of creating near fields with both enhanced asymmetric properties and intensities. They can be exploited for optical measurements that allow enantiomeric discrimination at detection levels greater than 6 orders of magnitude than is achieved with conventional chirally sensitive spectroscopic methods based on circularly polarized light. The optimal approach for exploiting nanophotonic platforms for chiral detection would be to use spectroscopic methods that provide a local probe of changes in the near field environment induced by the presence of chiral species. Here we show that surface enhanced Raman spectroscopy (SERS) is such a local probe of the near field environment. We have used it to achieve enantiomeric discrimination of chiral helicoid nanoparticles deposited on left and right-handed enantiomorphs of a chiral metafilm. Hotter electromagnetic hotspots are created for matched combinations of helicoid and metafilms (left-left and right-right), while mismatched combinations leads to significantly cooler electromagnetic hotspots. This large enantiomeric dependency on hotspot intensity is readily detected using SERS with the aid of an achiral Raman reporter molecule. In effect we have used SERS to distinguish between the different EM environments of the plasmonic diastereomers produced by mixing chiral nanoparticles and metafilms. The work demonstrates that by combining chiral nanophotonic platforms with established SERS strategies new avenues in ultrasensitive chiral detection can be opened.
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