Over the past few years, research on extracellular vesicles has attracted significant interest because they are present in a wide range of eukaryotic and prokaryotic organisms. These vesicles are known to play a major role in many pathological and physiological processes and are often referred to as microvesicles that are created by cell membrane budding, or exosomes that are generated from the cell endosome. The structure, cellular origin, characterization and functions of these microvesicles are a topic of much debate. The research community is also debating the size of these vesicles, despite the fact that exosomes are known to be smaller in size which is often 100nm in diameter or less, whereas microvesicles are larger with a diameter of up to 1µm.
Nanoparticle Tracking Analysis, or NTA, is a technique used for measuring and analyzing single particle size and concentration. The increasing use of this method has driven the need to reduce variability and user input and offer inter-laboratory consistency in terms of concentration and size measurements. In order to obtain highly precise, accurate, and reproducible concentration measurements on different types of nanoparticles, the NTA concentration measurement has been altered considerably. Repeatability and reproducibility of concentration measurements have been increased significantly, while eliminating measurement sensitivity to user settings over the suggested concentration range for NTA analysis.
To acquire the particle size distribution of samples in liquid suspension, the NTA technique uses the properties of Brownian motion and light scattering. When a laser beam is passed through the sample chamber, the particles in suspension that fall in the laser beam path disperse light in such a way that they can be observed through a 20x magnification microscope. A camera mounted on this microscope records a video file of the movement of the particles under Brownian motion, within its field of view.