Hydrodynamics and Actuation of Magnetic Bacteria in Confined Geometries:Single cells to swarms

受限几何形状中磁性细菌的流体动力学和驱动：单细胞到群体

• 批准号: 1710598
• 负责人: Ratnasingham Sooryakumar
• 金额: $ 33万
• 依托单位: Ohio State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-08-01 至 2022-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1710598&HistoricalAwards=false
• 关键词: Hydrodynamics; Actuation; Magnetic; Bacteria; Confined

In order to navigate their environment, many bacteria and other living micro-organisms swim by rotating a flagellum, a slender helix-shaped attachment connected to the cell body. Near surfaces, the wake produced by this rotating flagellum produces complex forces and torques that act on the bacterium. This gives rise to a range of movements that depend on the orientation of the cell relative to the surface, as well as its rate of rotation and physical geometry. Understanding these interactions at surfaces is important in the study of individual motile bacteria as well as in the development of technologies that can controllably manipulate large micro-organism populations in fluid environments. The proposed investigations will take advantage of the unique features of an inherently magnetic bacterial species, M. magneticum AMB-1, of the magnetotactic bacteria (MTB) group. Their natural magnetism allows them to be externally manipulated, providing a new means of probing the fluid-based forces arising near surfaces. Experiments that explore the role of cell geometry and orientation, magnetic content and flagellar thrust will underlie the development of models for the swimming behavior of MTB and associated fluid flow patterns. MTB are also promising candidate organisms for biologically powered micro-actuation and robotics. In this vein, large scale cell assemblies permit several magnetic field-based devices such as "living liquid crystal" displays and bacterial "conveyor belts" to be developed. The project will undertake outreach activities for several high school teachers in the form of an annual summer workshop. Through these activities, high school students will be able to create a connection between a fun, familiar device, an Xbox controller for example, and concepts in physics, environmental science, biology and engineering disciplines (e.g. magnetism, bacterial habitats, microorganisms, Archimedes principle) in the classroom and laboratory.The realization of functional biology-based robotics at the microscopic level would introduce a paradigm shift in areas as diverse as materials manufacturing, nanotechnology and medicine. The proposed work will make major advances in this direction by investigating fundamental fluid-surface interactions of a model bacterial species (M. magneticum AMB-1) with innate magnetic properties. Together with micro-magnetic and micro-fluidics techniques, their magnetic organelles allow individual living bacteria and swarms be confined and guided to yield quantitative measures of the hydrodynamic and magnetic forces as well as torques that are central to their dynamics. These quantitative parameters will serve as the foundation for developing models of their hydrodynamics on scales ranging from single cells to swarms. Integrating actuation and control of living organisms in low Reynolds number surroundings will serve as the basis to enable several novel biological and bio-hybrid machines that operate in a micro-fluidic environments. The in-situ management of the relative positions of individual cells through designed magnetic surface patterns provides for a novel means to explore pairwise cell-cell interactions that have led to the discovery of novel collective behavior such as rotating filamentary bacterial clusters, living liquid crystal magneto-optical modulators and momentum generating "conveyer-belt" tracks in these environments where viscous forces dominate. The flow fields generated by the propulsion of these flagellated swimmers will be managed to construct microscopically tunable pumps, mixers and hydrodynamic assemblers. The project will undertake stimulating outreach activities for high school students and teachers that link physics, environmental science, biology and engineering disciplines both in the classroom and laboratory.

为了适应环境，许多细菌和其他活着的微生物通过旋转鞭毛游泳，鞭毛是一种连接到细胞体的细长螺旋状附件。在表面附近，这种旋转的鞭毛产生的尾流会产生复杂的力和扭矩，作用于细菌。这会产生一系列移动，这些移动取决于单元相对于曲面的方向，以及其旋转速度和物理几何图形。了解表面的这些相互作用对于研究单个可移动的细菌以及开发能够在流体环境中可控地操纵大量微生物种群的技术都很重要。拟议的调查将利用趋磁性细菌(MTB)组的一种固有磁性细菌物种--磁支原体AMB-1的独特特征。它们的天然磁性允许它们被外部操纵，提供了一种新的手段来探测在表面附近产生的基于流体的力。探索细胞几何和取向、磁含量和鞭毛推力的作用的实验将为开发MTB游泳行为和相关流体流动模式的模型奠定基础。结核分枝杆菌也是生物动力微驱动和机器人技术的很有前途的候选生物。在这种情况下，大规模电池组件允许开发出几种基于磁场的设备，如“活液晶”显示器和细菌“传送带”。该项目将以一年一度的暑期讲习班的形式为几名高中教师开展外联活动。通过这些活动，高中生将能够在一个有趣的、熟悉的设备，例如Xbox控制器，与课堂和实验室中的物理、环境科学、生物学和工程学科(如磁学、细菌栖息地、微生物、阿基米德原理)的概念之间建立联系。在微观层面实现基于功能生物学的机器人将在材料制造、纳米技术和医学等多个领域引入范式转变。拟议的工作将在这一方向上取得重大进展，通过研究具有天然磁性的模式细菌物种(磁支原体AMB-1)的基本流体-表面相互作用。与微磁和微流体技术相结合，它们的磁性细胞器允许限制和引导单个活细菌和群，以产生对其动力学至关重要的流体动力和磁力以及扭矩的定量测量。这些定量参数将作为建立从单个细胞到群体的尺度上的它们的流体动力学模型的基础。在低雷诺数环境中集成生物的驱动和控制将成为实现在微流控环境中运行的几种新型生物和生物混合机器的基础。通过设计的磁表面图案原位管理单个细胞的相对位置提供了一种新的方法来探索细胞与细胞的成对相互作用，这些细胞-细胞相互作用导致了新的集体行为的发现，如旋转的丝状细菌团、活的液晶磁光调制器和在这些粘性力占主导地位的环境中产生动量的“传送带”轨迹。这些有鞭毛的游泳者的推进产生的流场将被管理，以构建微观可调的泵、搅拌器和流体动力装配器。该项目将为高中生和教师开展激励性的外联活动，在课堂和实验室中将物理、环境科学、生物和工程学科联系起来。

项目成果

Tunable self-assembly of magnetotactic bacteria: Role of hydrodynamics and magnetism

• DOI: 10.1063/1.5129925
• 发表时间: 2020-01
• 期刊: AIP Advances
• 影响因子: 1.6
• 作者: C. Pierce;H. Wijesinghe;E. Osborne;E. Mumper;B. Lower;S. Lower;R. Sooryakumar