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

在该项目中，PI将引入一种新的定量技术，该技术允许系统研究生物物理学的几个基本领域，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，使用机械特性，可变形的颗粒作为吞噬目标。在吞噬作用期间，软颗粒经历空间和时间依赖性变形，其反映了由颗粒周围的推进细胞延伸（伪足）施加的瞬时力。结合伪足的同时成像的颗粒变形的高分辨率成像将提供前所未有的数据，细胞动力学和力学在吞噬作用。通过图像处理和弹性壳理论的应用，将提取使颗粒变形的细胞产生的力场。这项工作涉及吞噬作用的三个方面。首先，将表征吞噬作用的机械特征的稳健性和再现性。其次，测得的力的动态将与最突出的吞噬作用模型，它声称有三个阶段，至少有两个不同的和独立的收缩力的来源。最后，通过改变实验期间使用的噬菌体传感器的弹性模量来研究巨噬细胞的机械敏感性。生物物理学研究的迷人和戏剧性的方面，如一个细胞吃掉另一个细胞的视觉刺激过程或全息光镊将用于：（1）吸引4- 5年级学生每月一次的课后动手科学俱乐部;（2）激励佛罗里达国际大学（FIU）等大学的本科生追求定量生物物理学的职业生涯;（3）在具有挑战性的跨学科环境中广泛培养格鲁吉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.