4.5. Characterization of Small Extracellular Vesicles with Nanoparticle Tracking Analysis
STERILE
Size and concentration of small EVs were characterized by nano-particle tracking analysis (NTA). Samples containing small EVs were diluted with fresh sterile PBS–/– to a concentration allowing optimal measurements. Diluted samples were analyzed using the ZetaVIEW device from Particle Metrix (ZetaVIEW S/N 17-323, Inning am Ammersee, GER; Camera 0.743 μm/px; Software ZetaView 8.04.02). Prior to each measurement session, daily performance was assessed with polystyrene size standard beads PS100 at a known concentration and size. Measurements were performed at the following settings: 24 °C, sensitivity 70, shutter 100, minimal brightness 25, minimal area 6, maximum area 5000. After injection of the sample into the chamber, it was allowed to equilibrate for 4 min before the measurement (each three rounds at eleven positions). All valid measurements per sample were averaged.