High Sensitivity Protein Characterisation for Multiple Applications

The new Zetasizer Nano ZSP from Malvern Instruments is a high specification dynamic light scattering system that delivers unique protein characterisation capabilities in a single, easy to use instrument. This top-of-the-range addition to Malvern’s established Zetasizer Nano family enables highly sensitive measurement of zeta potential, for rapid, reliable measurement of the electrophoretic mobility of proteins, and subsequent calculation of the key parameter of protein charge. Measuring protein mobility (or zeta potential) by dynamic light scattering is faster and more convenient than conventional methods such as capillary electrophoresis and iso-electric focussing. Furthermore, the Zetasizer Nano ZSP requires only 20 microlitres of sample and measures at concentrations down to 1mg/mL.

Key to achieving superior protein mobility measurements are a highly sensitive measurement system, the ability to protect the sample from aggregation, and flexible software that presents data in an immediately usable format. The Zetasizer Nano ZSP has the count rate sensitivity needed to easily measure weakly scattering samples such as proteins, and the instrument’s protein mobility measurement process is designed to maximise measurement quality using three specific features. Firstly, by combining size and zeta potential measurements the Zetasizer software can ensure that no aggregates are forming during the measurement, and warn the user is this does start to occur. Secondly, mobility measurements are performed in groups of sub-runs to allow extended periods of cooling, reducing the possibility of aggregation through heating. And thirdly, automatic optimisation of measurement settings minimises denaturation and aggregation during mobility measurements.

A suite of protein calculators has been added as part of the software developments that accompany the launch of the Zetasizer Nano ZSP, which are included with the instrument as standard. These include a dynamic DLS Debye Plot which allows calculation of the DLS interaction parameter, especially useful in protein formulation for biological therapeutics. There is also the ability to calculate protein charge from protein mobility, F(ka) from the Henry equation, interparticle distance, and thermodynamic diameter (virial radius).