University Science Instrumentation Centre (USIC)
Bharathidasan University
Tiruchirappalli - 620 024, Tamil Nadu, India

Dynamic light scattering (DLS) with zeta potential

Dynamic light scattering (DLS), also known as photon correlation spectroscopy (PCS), is a very powerful tool for studying the diffusion behaviour of macromolecules in solution. The diffusion coefficient, and hence the hydrodynamic radii calculated from it, depends on the size and shape of macromolecules. In this review, we provide evidence of the usefulness of DLS to study the homogeneity of proteins, nucleic acids, and complexes of protein–protein or protein–nucleic acid preparations, as well as to study protein–small molecule interactions. Further, we provide examples of DLS’s application both as a complementary method to analytical ultracentrifugation studies and as a screening tool to validate solution scattering models using determined hydrodynamic radii.

The sample is illuminated by a laser beam and the fluctuations of the scattered light are detected at a known scattering angle θ by a fast photon detector. Simple DLS instruments that measure at a fixed angle can determine the mean particle size in a limited size range. Dynamic light scattering (DLS) is based on the Brownian motion of dispersed particles. When particles are dispersed in a liquid they move randomly in all directions. The principle of Brownian motion is that particles are constantly colliding with solvent molecules. Dynamic light scattering (DLS) is a technique in physics that can be used to determine the size distribution profile of small particles in suspension or polymers in solution.


Specific Features of the Dynamic light scattering (DLS)

  •   Particle size, zeta potential, molecular weight, and second virial coefficient all in one instrument.
  •   Wide range of particle sizes and concentrations.
  •   Particles size measurements at both 90° and 173°.
  •   Multiple particle size measurement modes for working with small particles and weak scatterers.
  •   Small volume cells for both particle size and zeta potential.
  •   Extremely low sample volume makes it possible to measure precious or rare samples.
  •   Modern signal processing electronics efficiently convert optical signals to mobility and zeta potential information. There is no need to manually calculate particle velocity or match speeds.

Technical Specifications

Measurement range Particle diameter: 0.3 nm - 8.0 μm
Measurement Accuracy Particle size: ISO 13321/22412 compliant. NIST traceable polystyrene latex particle standard: 100 nm measurement accuracy = +/- 2%
Measurement time Approx. 2 minutes in general for particle size analysis
Sampling cell Cuvette cell
Sampling volume 12 μL~ 4 mL*

Zeta Potential

Measurement range -200 – +200mV
Measurement time Approx. 2 minutes in general
Sampling cell Dedicated disposable cell or dip cell
Sampling volume ~100 μL for disposable cell


The dynamic light-scattering technique has a number of advantages over other methods. For example, it is possible to conduct experiments with wide range of sample buffer and wide range of temperature as well as concentrations. DLS is also a non-invasive technique that requires comparatively low amounts of sample and provides reliable estimates of the quality of preparation rapidly. In the following sections, we describe applications of DLS to study homogeneity of proteins, RNA, and their complexes.

Details of Dynamic light scattering (DLS) with zeta potential

Sponsored AgencyDST- PURSE programme (Phase -2) (Sanction Order No- SR/PURSE Phase 2/16 (C)/2017)

Tariff Details: (per slide)

Name of the Instrument BDU Departments Affiliated Colleges Other Universities / Institutes Industries / Non-academics
Dynamic light scattering (DLS)  300  350  500  1000

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