Dynamic Light Scattering (DLS) Measurements of Particles in Solution

Dynamic light scattering measurements are used to obtain the particle diameters and the surface charge of the nanoparticles in solution phase. Particles suspended in liquids are in Brownian motion as a result of random collisions with solvent molecules. This motion causes particle diffusion through the medium. According to the Stokes-Einstein equation, the diffusion coefficient (D) is inversely proportional to the particle size (d). In this technique, the fluctuations in time of scattered light from the particles in Brownian motion are measured. By calculating the auto correlation functions of the time dependent intensity fluctuations hydrodynamic diameter is obtained by particle light scattering while zeta potential is obtained using the electrophoretic light scattering and laser doppler method.

These measurements are obtained directly by the Beckman Coulter Delsa Nano Submicron Particle analyzer. Depending on the exact sample characteristics and the required measurement the sample holder is selected from disposable size/zeta cell, flow cell, high concentration cell, flat surface cell and low conductivity cell.