Biomacromolecular Stereostructure Mediates Mode Hybridization in Chiral Plasmonic Nanostructures
Biomacromolecular Stereostructure Mediates Mode Hybridization in Chiral Plasmonic Nanostructures
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DOI：
10.1021/acs.nanolett.6b02549
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发表时间：
2016-09-01
期刊：
影响因子：
10.8
通讯作者：
Kadodwala, Malcolm
中科院分区：
文献类型：
--
作者：
Jack, Calum;Karimullah, Affar S.;Kadodwala, Malcolm
等离子体场的折射率灵敏度已经： 在分析技术中得到了 20 多年的应用。虽然这种灵敏度可用于达到阿托摩尔检测水平，但它们本质上是感知预定分析物是否存在的二元测量。使用等离子体场不是为了感测有效折射率，而是为了提供有关介质结构特征的更多“颗粒”信息，提供了更丰富的信息输出，这为创建新的强大且灵活的传感技术提供了机会，而不受合成化学识别元素的需要的限制。在这里，我们报告了一种新的等离子体现象，该现象对生物大分子结构敏感，而不依赖于测量有效折射率。手性生物材料介导手性固体-逆等离子体结构的电模式和磁模式的杂交，从而导致反射率和手性光学特性发生可测量的变化。该现象源于生物材料的电偶极磁偶极响应，因此对提供α螺旋、β折叠和无序基序的独特指纹的生物大分子二级结构敏感。这种现象可以在亚手性等离子体场（即手性不对称性低于圆偏振光的场）中观察到，从而解除了对产生具有增强手性场的结构的限制，从而为纳米结构设计提供了更大的灵活性：为了证明这种现象的功效，我们检测并表征了皮克数量的简单模型螺旋生物聚合物和更复杂的真实蛋白质。
The refractive index sensitivity of plasmonic fields has been: exploited for over 20 years in analytical technologies. While this sensitivity can be used to achieve attomole detection levels, they ate in essence binary measurements that sense the presence/absence of a predetermined analyte. Using plasmonic fields, not to sense effective refractive indices but to provide more "granular" information about the structural characteristics of a medium, provides a more information rich output, which affords opportunities to create new powerful and flexible sensing technologies not limited by the need to synthesize chemical recognition elements. Here we report a new plasmonic phenomenon that is sensitive to the biomacromolecular structure without relying on measuring effective refractive indices. Chiral biomaterials mediate the hybridization of electric and magnetic modes of a chiral solid-inverse plasmonic structure, resulting in a measurable change in both reflectivity and chiroptical properties. The phenomenon originates from the electric-dipole magnetic-dipole response of the biomaterial and is hence sensitive to biomacromolecular secondary structure providing unique fingerprints of alpha-helical, beta-sheet, and disordered motifs. The phenomenon can be observed for subchiral plasmonic fields (i.e., fields with a lower chiral asymmetry than circularly polarized light) hence lifting constraints to engineer structures that produce fields with enhanced chirality, thus providing greater flexibility in nanostructure design: To demonstrate the efficacy of the phenomenon, we have detected and characterized picogram quantities of simple model helical biopolymers and more complex real proteins.