Instrument development for vibrational circular dichroism imaging

摘要 分子手性是决定生命和推动重大研究的许多化学过程的核心。 在发育和疾病方面。所有的生命都与自然产生的分子和远程分子具有手性不对称性 具有明显的惯用手的集合。许多外源分子，例如那些用作药物的分子，也 对其有益于人类健康的功效具有明显的对映体依赖性。因此，测量 分子手性在整个医学科学中都是至关重要的。振动圆二向色性(VCD) 光谱学已经成为定量手性和分子结构的强大平台。然而， 由于技术挑战，成像技术尚未得到演示。VCD测量主要是 均质材料，整齐的或在溶液中，用灵敏的傅里叶变换红外(FT-IR)探测 分光计。显微镜需要将典型的感测体积减小约105并提高速度 这将使成像成为可能。我们没有使用FT-IR光谱，而是建立了一个定制的量子级联 激光(QCL)显微镜演示点扫描VCD仪器的可行性 在透射式和透射式配置中，快速跨越所有指纹区域波长的光谱。 此外，我们还首次展示了我们的仪器对特定地点的VCD成像性能 生物组织样本的手性图谱。然而，可行性数据也指出了几项技术 和概念上的挑战，这个项目试图在开发一个实际的原型中解决这些挑战。原型机 将在这里开发一种名为振动圆二色成像显微镜或VIM的设备，旨在记录手性 从显微镜下不同种类的生物医学样本中提取。我们提出了一种使用激光扫描的VIM设计 最小化伪影和最大化信号的方法。从全新的设计开始，我们将使用商业和 定制光学器件、用于控制和数据管理的定制电子设备以及用于开发 原型。接下来，我们对VCD成像过程进行了建模，并提出了VIM的分析方法。这个 这里开发的理论模型建立在我们的红外显微镜模型的基础上，并将指导原型开发 同时最终为记录的数据提供更大的准确性、精确度和保证。最后，我们验证了 使用表征良好的样品的VIM的性能和广泛的实用性。共同努力，这项工作将开发出新的 VCD成像技术开启了测量和研究各种生物问题的能力。

Abstract Molecular chirality is at the heart of many chemical processes that determine life and drives significant research in development and disease. All life has chiral asymmetry with naturally occurring molecules and long-range assemblies being of distinct handedness. Many exogenous molecules, for example those useful as drugs, also have a distinct enantiomeric dependence for their efficacy in benefiting human health. Thus, measurement of molecular chirality is of critical importance across the medical sciences. Vibrational Circular Dichroism (VCD) spectroscopy has emerged as a powerful platform for quantifying chirality and molecular structure. However, imaging has not been demonstrated due to technological challenges. VCD measurements are largely of homogeneous materials, neat or in solution and probed with sensitive Fourier transform infrared (FT-IR) spectrometers. Microscopy would require ~105 reduction of the typical sensing volume and increase in speed that would make imaging feasible. Instead of utilizing FT-IR spectroscopy, we built a custom quantum cascade laser (QCL) microscope to demonstrate feasibility of a point scanning VCD instrument capable of acquiring spectra rapidly across all fingerprint region wavelengths in both transflection and transmission configurations. Moreover, for the first time, we also demonstrate the VCD imaging performance of our instrument for site-specific chirality mapping of biological tissue samples. However, the feasibility data also point to several technological and conceptual challenges that this project seeks to address in developing a practical prototype. The prototype to be developed here, termed vibrational circular dichroism imaging microscope or VIM, aims to record chirality from microscopically heterogeneous biomedical samples. We propose a design for VIM using a laser scanning approach to minimize artifacts and maximize signal. Starting from a de novo design, we will use commercial and custom optics, custom electronics for control and data management, and in-house software to develop the prototype. Next, we model the VCD image formation process and develop the analytical methods for VIM. The theoretical model developed here builds on our models of IR microscopy and will guide prototype development while ultimately provide greater accuracy, precision and assurance to data recorded. Finally, we validate the performance and broad utility of VIM using well-characterized samples. Together, the work will develop new VCD imaging technology that opens capability to measure and research a wide variety of biological problems.