Single Particle Characterization and Isolation of Extracellular Vesicles

细胞外囊泡（Extracellular vesicles，EV）是由所有生命形式如细胞、细菌和酵母分泌的亚微米级生物颗粒。EV携带来自释放它们的细胞的货物分子（例如，蛋白质、脂质、核酸）。这些可以反过来在摄取它们的细胞中发挥生物学作用，例如诱导生长、增殖、迁移，甚至分泌可溶性生物活性因子。EV在压力，损伤和疾病的情况下释放，但也可以作为生物实体之间的一般通信手段来完成特定任务。单个EV表面的蛋白质和标记物引导它们朝向其预期的靶细胞，然后吞噬它们。在复杂的环境中，如细菌生物膜和生物流体，来自系统中所有细胞的EV一起释放到细胞外环境中。由于EV具有几乎相同的生物物理特性，因此目前的纯化方法将EV作为整体分离。因此，几乎不可能研究EV多样性或分离系统中特定细胞发出的EV。因此，人们对EV多样性、亚群以及它们如何影响复杂和异质系统中受体细胞的行为知之甚少。

Extracellular vesicles (EVs) are submicron-sized biological particles secreted by all forms of life such as cells, bacteria and yeast. EVs carry as cargo molecules from the cells from which they were released (e.g., proteins, lipids, nucleic acids). These can in turn exert biological effects in cells that uptake them such as inducing growth, proliferation, migration and even the secretion of soluble bioactive factors. EVs are released in instances of stress, damage and disease, but can also be released as a means of general communication between biological entities to accomplish a specific task. Proteins and markers at the surface of individual EVs guide them towards their intended target cells that will then engulf them. In complex environments such as bacterial biofilms and biological fluids, EVs from all the cells in the system are released together into the extracellular environment. Because EVs share nearly identical biophysical properties, current purification methods isolate EVs as a bulk. It is therefore nearly impossible to study EV diversity or isolate EVs emanating from specific cells in the system. As such, very little is known about EV diversity, subpopulations and how they impact the behavior of recipient cells in complex and heterogeneous systems.