Nanoparticle Tracking Analysis (NTA)

Nanoparticle tracking analysis (NTA) is a widely used technique for measuring the size and concentration of nanoparticles, including extracellular vesicles, in solution. It works by illuminating a diluted sample with a laser and tracking the Brownian motion of individual light-scattering particles under a microscope, then applying the Stokes-Einstein equation to convert each particle’s movement into an estimated size. NTA is considered reasonably accurate for sizing particles above roughly 50 nm, but its concentration measurements are less reliable, which has motivated complementary approaches such as flow cytometry for quantifying extracellular vesicle preparations.