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
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.
- White Paper: “Developing a Bioformulation Stability Profile”
Application Note “Using A2 and kD to assess protein interactions in formulations”
Application Note “Using the Zetasizer APS to rapidly screen well plate data”
Application Note “Demonstrating that the Zetasizer APS eliminates cross contamination”
Technical Note “DLS Plate Sampling Technology”
- Technical Note”Guide to Using the APS SLS Macro” referencing an older technical note on molecular weight “MRK528-01 MW Measurements with the Zetasizer Nano“