Experimental Investigations of Single Liposome to Supported Bilayer Binding Events

Abstract

One of the primary ways in which cells interact with their environments is by release of extracellular vesicles. These cell-derived submicron sized containers are formed either from the cell plasma membrane (microvesicles) or secreted from multivesicular bodies (exosomes). These vesicles contain nucleic acids and proteins that have been suggested to play an important role in intercellular signaling and the process of molecular communication between cells. In microvesicle-mediated intercellular communication, vesicles released by a donor cell must bind to the plasma membrane of a recipient cell in order to deliver their cargo to the target. Despite the important physiological role of vesicle-plasma membrane fusion and vesicle endocytosis, the details of the physical interactions between microvesicles and the plasma membrane are still poorly understood. To better understand the forces which occur between microvesicles and cells, we experimentally investigate single liposome binding events with a supported lipid bilayer. We employed total internal reflection fluorescence (TIRF) microscopy to observe liposome interactions with a supported lipid bilayer, and compare the experimentally observed bond lifetimes to the theoretical estimates. Our experimental observations indicate that bond lifetimes increase with both increasing liposome size and decreasing temperature.