Formvar-coated Cu grids (300 mesh, Catalog #FCF300-Cu, Electron Microscopy Sciences) were glow-discharged using a Denton BenchTop™ Turbo setup and used freshly. 5 μL of a vesicle sample was added to formvarcoated Cu grid surface and allowed to sit for 3 min. The grids were washed by touching the surface of 2 drops of Milli-Q placed on a parafilm sheet. 3 drops of 1% uranyl acetate in ultrapure water were then added to the grid and the 3rd drop was allowed to sit on the grid for 1 min. Afterward, the excess staining solution was blotted into a filter paper. The grids were dried in air. Finally, the grids were imaged on a JEOL JEM-1400 microscope equipped with a Gatan OneView (4k×4k resolution) camera.