Glow discharged formvar carbon coated 400 mesh copper grid

Protein samples were visualized by negative-stain transmission electron microscopy. Concentrations were 100 μg/mL of protein for samples diluted in water and 50 μg/mL of protein diluted in TEN buffer. A glow-discharged formvar/carbon-coated 400 mesh copper grid (Ted Pella, Inc., Redding, CA) was floated on a 20 µl droplet of the sample suspension for 10 min, transferred quickly to 2 drops of deionized water followed by a droplet of 2% aqueous uranyl acetate stain for 1 min. The grid was blotted with filter paper and air-dried. Samples were observed using a JEOL JEM1230 transmission electron microscope operating at 80 kV (JEOL USA INC., Peabody, MA) and images were taken using a Gatan Orius SC1000 CCD camera with Gatan Microscopy Suite version 3.10.1002.0 software (Gatan, Inc., Pleasanton, CA).

EVs were visualized by negative-stain transmission electron microscopy (TEM) in the UNC Microscopy Services Laboratory. Briefly, this involved floating a glow-discharged formvar/carbon-coated 400 mesh copper grid (Ted Pella, Inc., Redding, CA, USA) on a 20μl droplet of the sample suspension for 12 min. This was transferred quickly to 2 drops of deionized water followed by addition of a droplet of 2% aqueous uranyl acetate stain for 1 minute. The grid was blotted with filter paper and airdried. Samples were then visualized at 80kV using a JEOL JEM-1230 transmission electron microscope operating (JEOL USA INC., Peabody, MA, USA). Images were taken using a Gatan Orius SC1000 CCD camera with Gatan Microscopy Suite version 3.10.1002.0 software (Gatan, Inc., Pleasanton, CA, USA).