Superchiral Light Generation on Achiral Substrates for High Sensitive Detection of Chiral Molecules

手性是生命中普遍存在的属性，存在于从左手氨基酸到右手葡萄糖的许多生物系统中。它引起了DNA、蛋白质等的固有手性，由于精确表征技术的不可用，迄今为止尚未探索。这些手性生物分子可以以双手对称存在，具有不可区分的物理性质，例如密度，分子量或电子和振动跃迁频率，使得它们几乎不可能用普通光谱技术区分。在这里，提出了一个独特的非手性等离子体表面，它优于以前的方法。在初步工作中，手性分子检测灵敏度比传统技术高四个数量级，但没有广泛和繁琐的样品制备和低得多的样品体积，被证明。手性分子的药理学和毒理学表征在制药工业和FDA批准过程中起着至关重要的作用。拟议的项目还将用于培训纳米光刻和设备制造的研究生。基于这些特性，提出的新型分子手性检测方案具有很高的商业价值，在不久的将来可能成为真实的世界传感技术。技术要点：提出的独特的腔耦合非手性等离子体表面在以下方面优于以往的方法：它不具有几何手性，因此没有来自基底的手性信号;它在暴露于目标分析物的上表面上产生强近场;近场是100%单手手性和翻转手性，仅取决于同一基板上的激发手性。由于简并等离子体激元和光子腔模之间的相干相互作用，这种独特的超手征近场产生机制是可能的。这些属性与任何先前的尝试相比是唯一的，其中不均匀的手性近场和结构CD减少了来自分子的手性信号。在初步的研究中，手性光-物质相互作用，通过表面增强的振动圆二色性与约四个数量级的增强检测灵敏度相比，传统的体积CD（VCD）技术被证明。所提出的系统将允许有效的手性轻物质相互作用的振动分子手性的检测相关的药物筛选的MIR域。与以前的演示中，需要两个独立的手性相反的手性基板，拟议的工作承诺手性近场相互作用的单一非手性等离子体基板铺平了道路，走向表面增强chiropical spectroscopy.该项目的主要重点将是开发一个敏感的手性化合物识别技术使用我们的非手性等离子体基板。该系统将以显著的手性药物化合物（如伊诺、沙利度胺、普萘洛尔、沙丁胺醇和异氟烷）为基准。这些手性化合物将使我们能够开始系统的表征，并将进一步扩展。对映异构体的药理学和毒理学表征在制药工业和FDA批准过程中起着至关重要的作用。因此，仍然存在对精确且廉价的有效对映体检测的积极需求。我们坚信，拟议的研究将使我们能够克服一些以前的挑战，使我们能够开发一个低成本，高通量，高灵敏度的手性分子检测technology.This奖项反映了NSF的法定使命，并已被认为是值得的支持，通过评估使用基金会的智力价值和更广泛的影响审查标准。

Chirality is a ubiquitous property of life, found at many levels of biological systems from left-handed amino acids to right-handed glucose. It gives rise to the inherent chirality to DNAs, proteins and more, which remained hitherto unexplored due to the unavailability of precise characterization techniques. These chiral biomolecules can be present in both handed symmetries with undistinguishable physical properties, such as density, molecular weight or electronic and vibrational transitions frequencies making them almost impossible to differentiate with common spectroscopic techniques. Here a unique achiral plasmonic surface is proposed, which outperforms previous approaches. In the preliminary work chiral molecule detection sensitivity that is four orders of magnitude higher compared to the conventional technique, but without the extensive and tedious sample preparation and at much lower sample volume, is demonstrated. Pharmacological and toxicological characterization of chiral molecules plays a crucial role in the pharmaceutical drug industry and FDA approval process. The proposed project will also serve to train graduate students in nanolithography and device fabrication. Based on these attributes the proposed novel molecular chirality detection scheme has high potential to generate commercial interests and can become real world sensing technique in near future.Technical: The proposed unique cavity-coupled achiral plasmonic surface outperforms previous approaches in the following aspects: It does not have geometrical chirality, hence no chiral signal from the substrate; It creates strong near-fields on the upper surface exposed to the target analyte; The near-field is 100% single-handed chiral and flip handedness depending only on the excitation handedness on the same substrate. Such a unique mechanism of superchiral near-field generation is possible due to the coherent interaction between degenerate plasmonic and photonic cavity modes. These attributes are exclusive compared to any previous attempts where inhomogeneous chiral near-field and structural CD diminishes chiral signal from molecules. In the preliminary studies, chiral light-matter interaction through surface enhanced vibrational circular dichroism with about four orders of magnitude enhancement in detection sensitivity compared to conventional volumetric CD (VCD) technique is demonstrated. The proposed system will permit efficient chiral-light matter interactions for the detection of vibrational molecular chirality in the MIR domain relevant for drug screening. Unlike previous demonstrations where two independent chiral substrates with opposite handedness were needed, the proposed work promises chiral near-field interaction on a single achiral plasmonic substrate paving the path towards surface enhanced chiroptical spectroscopy.The main focus of the project will be to develop a sensitive chiral compound identification technique using our achiral plasmonic substrates. The system will be benchmarked with pharmacologically significant chiral drug compounds like Ibuprofen, Thalidomide, propranolol, Albuterol, and Isoflurane. These chiral compounds will allow us to start the characterization of the system and will further expand. The pharmacological and toxicological characterization of enantiomers plays a crucial role in the pharmaceutical drug industry and FDA approval process. Therefore, there is still an active need for efficient enantiomer detection, precisely and cheaply. We strongly believe that the proposed research will allow us to overcome some of the previous challenges and enable us to develop a low cost, high throughput, high sensitive chiral molecule detection technique.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.