Dynamic light scattering (DLS)

At SOLVE:

A typical use of DLS at SOLVE, besides determining the size and size distribution, is to screen protein solutions for aggregates and particles. Our instrumentation enables us to operate the DLS both in cuvette format and in plate reader format for high-throughput analysis and screenings. Our instruments are temperature controlled allowing temperature stability to be investigated and to determined zeta-potential. We use DLS instrumentation from Wyatt Technology and Malvern.

Principle:

Dynamic light scattering (DLS), also referred to as quasi-elastic light scattering (QELS) or photon correlation spectroscopy (PCS), is a spectroscopic technique that measures the Brownian motion of particles/macromolecules in solution. The measured Brownian motion is related to the diffusion coefficient and from that the 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  antibody, peptides and proteins, to nanoparticles and viruses. Typical applications include screening of buffer conditions during formulation development, stability testing of proteins, aggregation detection, etc.

Pros

  • No (or minimum) method development
  • Fast (high-throughput)
  • Native conditions (concentration 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