EAGER: Propulsion of enzyme-coated Janus particles through complex environments

CBET-1544617PI：UnderHill，Patrick该项目的目标是合成一种能够自我推进的微米大小的颗粒，并表征颗粒在复杂流体中的运动。球形颗粒的一部分表面覆盖着一种酶，它与周围液体中的过氧化氢发生反应。颗粒表面的反应在整个颗粒上产生渗透压差，从而使颗粒移动。酶反应可以在周围介质中非常低的过氧化氢浓度下推动颗粒，这使得这种自我推进的颗粒适合用于对过氧化氢浓度敏感的生物系统。将测量一系列粘性流体的颗粒速度，包括作为生物介质模型的复杂流体。自推进颗粒是一种很有前途的交通工具，可以在从多相流体系统到生物组织的复杂环境中加强运输和运送分子货物。研究人员将让本科生和高中生参与该项目，并将研究成果用于他们所在机构的推广项目。该项目包括实验和理论研究，以量化和阐明胶体颗粒在非牛顿环境中自驱动运动的机制。这些实验将利用一类Janus粒子，通过在其部分表面涂上一种酶来推动自己。运动的结果是过氧化氢燃料在颗粒表面的溶液中发生反应，在颗粒周围产生不均匀的溶质分布，这导致了一种称为自扩散渗透的机制来推进。该项目将测试当前牛顿流体中自扩散渗透作用理论的预测，特别是粒子速度与流体粘度的相关性，然后研究在推进粒子尺寸尺度上均匀的更复杂的非牛顿流体中的运动。这将使用聚合物溶液，其中聚合物的旋转半径明显小于马达。这些结果将为自推进颗粒的设计和在复杂和多相流体中的使用奠定基础。

CBET - 1544617PI: Underhill, PatrickThe goals of this project are to synthesize a micron-sized particle that is capable of self-propulsion and to characterize the motion of the particle in complex fluids. A portion of the surface of the spherical particle is coated with an enzyme that reacts with peroxide in the surrounding fluid. The reaction at the particle surface creates an osmotic pressure difference across the particle, which causes it to move. The enzymatic reaction can propel the particle at very low peroxide concentrations in the surrounding media, which makes the self-propelled particle a candidate for use in biological systems that are sensitive to peroxide concentration. The velocity of the particle will be measured for a series of viscous fluids, including complex fluids that are models of biological media. Self-propelled particles are promising vehicles to enhance transport and deliver molecular cargoes in complex environments ranging from multiphase fluid systems to biological tissues. The researchers will involve undergraduate and high school students in the project and use results of the research in outreach programs at their institution.The project comprises experimental and theoretical studies to quantify and elucidate mechanisms for the self-driven motion of colloidal particles through non-Newtonian environments. The experiments will utilize a class of Janus particles that propel themselves using an enzyme coated on part of their surface. Motion results from the reaction of a peroxide fuel in solution on the particle surface producing a non-uniform distribution of solutes around the particle, which leads to propulsion by a mechanism called self-diffusiophoresis. The project will test predictions of current theories of self-diffusiophoresis in Newtonian fluids, especially the dependence of particle velocity on fluid viscosity, and then examine motion in more complex, non-Newtonian fluids that are homogeneous on the size scale of the propelling particle. This will be done using polymer solutions in which the polymer radius of gyration is significantly smaller than the motor. Results will form a foundation for self-propelled particle design and use in complex and multiphase fluids.