Malvern Zetasizer Nano ZSP
The Zetasizer Nano is a combined light scattering system suitable for characterisation of colloid dispersions, nanoparticles and macromolecules such as polymer and protein solutions (3.8 nm to 100 μm, concentration ~0.1ppm to 40%w/v, pH 1-13, sample dependent).
Dynamic Light Scattering (DLS) is used to measure the diffusion of particles under Brownian motion, and convert this to a size distribution using the Stokes-Einstein relationship. Non-invasive back-scatter (NIBS) technology is incorporated to give better sensitivity and the ability to measure particles at high concentration.
Electrophoretic Light scattering (ELS) is used to measure zeta potential. An electric field is applied to the sample and mixed mode measurement, phase analysis light scattering (M3-PALS) is used to measure electrophoretic mobility and determine a zeta potential distribution.
Static Light Scattering (SLS) is used to determine the molecular weight (> ~1KDa) of proteins and polymers. The scattering intensity at a range of concentrations is measured to construct a Debye plot. From this the weight-average molecular weight and second virial coefficient can be calculated to provide a measure of protein solubility.