Collaborative Research: Chiral Objects in Microfluidic Shear Flows: Chiral Separation and Microbial Locomotion

PI结合微流控实验和数学建模，研究剪切流中手性颗粒和手性生物体的动力学。手性粒子是形状不能叠加在镜像上的粒子，对基础科学和技术都有广泛的兴趣。手性粒子在生物学中普遍存在：例如，氨基酸就是手性分子。由于生命过程中涉及的分子间反应依赖于参与分子的几何构型，不同的手性药物、信息素、农药和气味的对映体具有不同的生物学效应。因此，人们对设计从两种对映体混合物中分离纯对映体样品的方法非常感兴趣。此外，在生物学中，手性不仅发生在分子尺度上，也发生在细胞尺度上。许多游泳微生物具有手性螺旋结构，例如大多数细菌的推进器。与此同时，水环境中的微生物不断受到剪切的影响，例如海洋、地下水、工业管道和导管。该项目有两个具体目标：(I)利用剪切中颗粒的手性相关运动，在微型通道中通过手性分离混合对映体，以及(Ii)了解微生物的手性形态如何影响它们的游动和觅食。这些目标是统一的，最终目标是更好地了解手性粒子在剪切水中的行为，因此服从于相同的实验和理论研究工具。这项拟议的研究有可能(I)通过开发一种比目前可用的分离策略更简单、成本更低的分离策略，来转变我们将外消旋混合物分离成组分对映体的技术能力，以及(Ii)提高我们对微生物运动的理解，其应用范围从自然系统中限制元素的循环到疾病的传播和生物形成。

The PIs investigate the dynamics of chiral particles and chiral organisms in shear flows, using a combination of microfluidic experiments and mathematical modeling. Chiral particles are particles with shapes that cannot be superimposed upon their mirror images, and are of broad interest for both basic science and technology. Chiral particles are ubiquitous in biology: for example, amino acids are chiral molecules. Since the intermolecular reactions involved in life processes depend on the geometry of participating molecules, different enantiomers of chiral drugs, pheromones, pesticides, and odorants have different biological effects. As a consequence, there is much interest in devising ways to separate pure enantiomeric samples out of a mixture of both enantiomers. Furthermore, in biology chirality occurs not only at the molecular scale, but also at the cellular scale. Many swimming microorganisms have chiral helical structures, such as the propulsion-generating flagella of most bacteria. At the same time, the watery environments of microbes are constantly subject to fluid flow, and hence shear, such as in the oceans, groundwater, industrial pipe flow, and catheters. This project has two specific aims: (i) exploiting the chirality-dependent motion of particles in shear flows to separate a mixture of enantiomers by handedness in a microfluidic channel, and (ii) understanding how chiral morphologies of microbes affect their swimming and foraging. These aims are unified by the ultimate goal of better understanding the behavior of chiral particles in shear flows, and hence amenable to the same experimental and theoretical research tools. The proposed research has the potential to (i) transform our technological capability to separate a racemic mixture into component enantiomers, by developing a simpler and less expensive separation strategy than those currently available, and (ii) improve our understanding of microbial motility, with applications ranging from the recycling of limiting elements in natural systems to the spreading of disease and biofilm formation.