The Phagosensor Technique: Quantifying the force fields generated during phagocytosis using deformable microcapsules

在这个项目中，PI将引入一种新的定量技术，允许对生物物理学的几个基本领域进行系统的研究，包括吞噬作用，肌动蛋白细胞骨架及其与膜的偶联，以及机械转导。这种方法被称为吞噬传感器技术，它使用具有机械特征的可变形颗粒作为吞噬目标。在吞噬过程中，软颗粒经历空间和时间相关的变形，这反映了颗粒周围推进的细胞延伸（伪足）施加的瞬态力。颗粒变形的高分辨率成像结合伪足的同步成像将提供有关吞噬过程中细胞动力学和力学的前所未有的数据。通过图像处理和弹性壳理论的应用，提取细胞产生的使粒子变形的力场。这项工作涉及吞噬作用的三个方面。首先，吞噬作用的机械特征的稳健性和可重复性将被表征。其次，测量的力动态将与最突出的吞噬模型相关，该模型声称存在三个阶段，至少有两个不同且独立的收缩力来源。最后，通过改变实验中使用的PhagoSensors的弹性模量，将研究巨噬细胞的机械敏感性。生物物理研究的迷人和戏剧性方面，如一个细胞吃掉另一个细胞的视觉刺激过程或全息光学镊子将用于：(1)吸引4-5年级学生每月一次的课后实践科学俱乐部；(2)鼓励佛罗里达国际大学（FIU）等高校的本科生从事定量生物物理学的研究；(3)在具有挑战性的跨学科环境中广泛培训佐治亚理工学院的本科生。

In this project the PI will introduce a new quantitative technique that permits systematic studies of several fundamental areas in biological physics, including phagocytosis, the actin cytoskeleton and its coupling to membrane, and mechanotransduction. The approach, called the PhagoSensor Technique, uses mechanically characterized, deformable particles as the phagocytotic target. During phagocytosis, the soft particle experiences spatially and time-dependent deformations which reflect the transient forces exerted by the advancing cell extensions (pseudopodia) around the particle. High resolution imaging of the particle deformations combined with simultaneous imaging of the pseudopodia will provide unprecedented data regarding cell dynamics and mechanics during phagocytosis. The cell-generated force field that deforms the particle will be extracted via image processing and application of elastic shell theory. This work addresses three aspects of phagocytosis. First, the robustness and reproducibility of the mechanical signature of phagocytosis will be characterized. Second, the measured force dynamics will be correlated with the most prominent model of phagocytosis, which claims that there are three phases with at least two different and independent sources of contractile force. Last, the mechanosensitivity of macrophage cells by varying the elastic moduli of the PhagoSensors used during experimentation will be investigated. The fascinating and dramatic aspects of the biophysical studies, such as the visually stimulating process of one cell eating another or the holographic optical tweezers will be used to: (1) captivate 4-5th graders once a month in a hands-on after school Science Club; (2) to inspire undergraduates in universities like Florida International University (FIU) to pursue a career in quantitative biophysics; and (3) to extensively train undergraduates at Georgia Tech in a challenging interdisciplinary environment.