Dynamic Light Scattering (DLS)

At SOLVE:

Typical uses of DLS at SOLVE is, besides determining the size and size distribution of protein solution, to screen sample solutions for aggregates and particles. The instrumentation enable us to operate DLS both in cuvette format and in plate format for high throughput analysis and screenings. The instruments are temperature controlled allowing temperature stability to be investigated and also allow zeta-potential to be determined. We use DLS instrumentation from Wyatt and Malvern.

Principle:

DLS also referred to as quasi-elastic light scattering (QELS) or photon correlation spectroscopy (PCS) is a spectroscopic technique which measure the Brownian motion of particles/macromolecules in solution. The measured Brownian motion is related to the diffusion coefficient, and from that hydrodynamic size (Stokes radius) can be obtained.

Applicability:

DLS is applicable to particles and macromolecules from ~ 1 nm to ~1 µm. It can thereby be applied to everything from  peptides and proteins, to nanoparticles and viruses. Typical uses are for screening of buffer conditions during formulation development, stability testing of proteins, aggregation detection, etc.

Pros

  • No (or at least limited) method development
  • Fast (high throughput)
  • Native conditions (conc and solvent)
  • Low sample volume (down to ~30µl)
  • Experimentally relatively straight-forward
  • Low surface area and no shear

Cons

  • Limited resolution
  • Semi-quantitative
  • Difficult to evaluate for polydisperse samples
  • Not suited for complex matrices
  • Molar mass and Mw info through assumptions
  • Sensitive to particulate impurities