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The ZetaView® is a Nanoparticle Tracking Analyser that enables the determination of hydrodynamic particle size, zeta potential and concentration. It finds application in the fields of proteins, microvesicles, exosomes, coatings, emulsions, fillers, food sciences, ceramics, colloids, pigments, polymers, abrasives, silica, inks, carbon nanotubes, novel materials in general, gold and silver sols etc. Classical micro-electrophoresis is combined with state-of-the-art technologies of laser scattering optics, control technique and video-image processing.
Irene Schaffner PhD, Jakob Wallner BSc
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Methods & Expertise for Research Infrastructure
Nanoparticle Tracking Analysis uses the two properties light scattering and Brownian motion to determine particle size distributions in solutions. It uses classical micro-electrophoresis, where an electric field is applied to particles in solution. Depending on polarity, they either move to the anode or cathode. To capture the movement of particles in the ZetaView®, a fine laser beam is focused onto the particles moving within an applied electrical field within the cell unit. A light scattering microscope with a video camera monitors light scattered from the particles. From the video data, a velocity distribution can be derived. The electrophoretic mobility depends on the net charge on the particles surface and can be related to the zeta potential by applying the Helmholtz-Smoluchowsky equation.
From the direct observation of Brownian motion, the translational diffusion constant and subsequently the hydrodynamic radius of the particles can be calculated by applying Stokes-Einstein relationship. Particles of 10 nm to 20 µm size can be detected with this system.
In addition, analysing the video frames allows the determination of particle numbers. Normalising them to the scattering volume per relevant size class, the particle concentration can be derived. The concentration that can be determined ranges from 105 particles/cm³ to a maximum of 1010 particles/cm³. While dynamic light scattering (DLS) is ideally suited for analysis of highly concentrated samples, NTA can be used to measure low concentration samples.