To complete the other variables in this equation, sample temperature is measured and viscosity is user-defined. The diameter calculated is the hydrodynamic diameter. The standard deviation of the diffusion coefficient measurement is connected to the width of the size distribution and usually converted to a polydispersity index (PDI).
The second method of DLS analysis draws upon a library of DLS data to recreate the measured data and determine a sample’s size distributions (Figure 3). Both of these analysis methods follow the latest ISO standards for particle size analysis by DLS as stated within ISO 22412:2017.
In the world of biologics, DLS will not only tell you the size of your sample, it is also a quick check to determine if your sample is aggregated. Since large particles scatter light intensely, DLS can detect even very rare aggregates in a sample. Sending up a warning flag on protein aggregates can save you from relying on data from a sample already past its prime, or explaining why your antibody is no longer performing at its peak.
All Unchained Labs DLS instruments deliver:
Check out our dynamic light scattering instrument line-up below, with three solutions designed to solve biologics problems.
Stunner is the only system out there that takes UV/Vis concentration and dynamic light scattering measurements from the same sample in the same run. Pairing up these techniques checks concentration, hydrodynamic size, polydispersity, and detection of aggregates off your to-do list in one shot – using only 2 µL of sample. And concentration measurements are spot-on with accuracy within 2% and precision within 1%.
UV/Vis and DLS also combine to uniquely measure colloidal stability of your samples with kD or B22 data. Instead of making assumptions, Stunner takes an accurate read on concentration for every data point and combines that with DLS data to show how your protein is interacting with itself in solution.
Uncle is the all-in-one biologics stability platform designed to crank out data on stability and formulation in just hours with way less protein. Uncle combines DLS, fluorescence and SLS with temperature control to deliver 12 powerful applications for characterizing biologics. Only 9 µL of sample gets you size info from DLS, and info on protein unfolding and aggregation from a thermal ramp experiment.
Biologics researchers can now find the right tool built for biologics problems across three dynamic light scattering instruments. Have a question or can’t wait to find out more? Here’s the best way to reach us: