Last week we offered a webex presentation titled “Speed your way through protein formulation screening by automating your measurements: A2/B22 with the Zetasizer APS

The presentation had a focus on protein formulation, where often the objective is to assess protein stability as a function of various parameters. Here, light scattering can be used as a tool to assist in screening conditions:

  • Monitor: Aggregation temperature, Dynamic Light Scattering (DLS) vs temperature
  • Predict: Interaction parameter, DLS vs concentration
  • Predict: Second Virial Coefficient, Static Light Scattering (SLS) vs concentration
Zetasizer APS

While the Zetasizer APS has previously been used for dynamic light scattering [individual records with hydrodynamic size obtained from intensity fluctuations] the system can now also be used for static light scattering [molecular weight record groups with mw and second Virial coefficient obtained from the average scattering intensity]. This software addition is compatible with any existing Zetasizer APS.

A recording of the webinar is now available describing how to perform static light scattering on standard 96 or 384 well plates.

A question not addressed in the presentation was: How can I find the range of concentrations appropriate for the specific molecule I am working on?


There is a special calculator in the software that provides a suggestion for you.  This feature can be accessed from within the software under Tools → Calculators → tab Concentration Utilities to obtain the lower and upper suggested concentration for making molecular weight measurements. In the screenshot, the calculator shows a range of 0.1 to 1.0 mg/mL for a molecular weight of 150kDa. The estimate is for a protein, for a much smaller peptide of for example 3000Da the minimum recommended concentration for static light scattering would increase to 5 mg/mL. The technical note titled ‘Introduction to the calculators in the Zetasizer software‘ shows some of the background and references behind the various other calculators available in the software.


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