Dynamic Light Scattering (DLS)

DLS is so named as it measures the small changes in the intensity of light scattered from an ensemble of particles over very short time periods, it’s this dynamic change that DLS utilizes.

The intensity changes of the scattered light arise from the small movements that particles make as they are randomly bombarded by the surrounding solvent molecules, this is called Brownian Motion after Robert Brown who first observed the effect.

Scattered light from two or more moving particles will change phase with respect to each other, leading to constructive and destructive interference of the scattered light from the diffusing particles, seen as intensity fluctuations over short time periods.

DLS measures the rate of these light fluctuations using a high sensitivity single photon counting module. The rate of intensity change is directly related to the rate the particles move (diffuse) and to their particle size, by the Stokes-Einstein equation.

In simple terms the rate particles diffuse is related to their size and the viscosity of the suspending fluid; small particles will diffuse faster than larger particles.  The faster the particles diffuse the faster the scattered light intensity changes – the rate of this decay is what DLS uses to measure particle size.

This phenomenon and how it’s analyzed maybe better understood in our “Introduction to Dynamic Light Scattering” video.

DLS has become a well-established technique in nanoparticle characterization for drug delivery systems, ensuring precise size distribution analysis crucial for drug efficacy and stability.

Zetasizer Core facilitates the study of protein or vesicle size, polydispersity and aggregation kinetics, typically at the drug candidate and formulation screening stages where its ability to rapidly scan multiple candidates and condition samples using microplates, enabling researchers to quickly obtain the data to optimize formulations for efficacy and stability.

Zetasizer Advance offers similar capabilities but in a batch system, offering great data quality needed for those more critical measurements that may be needed in late-stage development, production and QC stages.  Zetasizer Advance and Zetasizer Core help the biopharmaceutical manufacturing sector ensure efficient drug discovery, development and  final product quality. 

At Malvern Panalytical, we offer state-of-the-art DLS instruments designed to meet the diverse needs of researchers and industry professionals. Our Zetasizer Advance Range combines precision, reliability, and user-friendly features to deliver accurate and insightful data.

Our Zetasizer Core offers unparalleled speed combing DLS, DSF and static light scattering, all with the convenience of sample presentation in microplate format, for insights into candidate and formulation screening and stability studies.

Key capabilities and advantages include: 

Zetasizer Advance

• Accurate, reliable and repeatable particle size analysis in a few minutes
  
• Multi-Angle Dynamic Light Scattering  (MADLS) improves the resolution of DLS and provides angular independent size results
• Simple measurement of per peak particle concentration
• Mean size only requires knowledge of the viscosity of the liquid
• Simple or no sample preparation, high concentration, turbid samples can be measured directly using NIBS
• Size measurement of sizes from <1 nm to 15 um
• Size measurement of molecules from MW < 1000 Da
• Low volume requirement (as little as 3 µL)
• At-line process systems available for control of nanoparticle manufacture
• Compliance with regulatory standards ISO 13321, ISO 22412, 21 CFR Part 11

Zetasizer Core

• Rapid screening by DLS (with SLS and DSF)
• High-quality DLS mode when you need to get the best sizing data
• Zero proprietary consumables: needs standard microwell plates only
• 4 µL minimum sample volume (1536-well)
• 5 clicks from setup to results
• Run up to 192 samples per minute
• 35+ years of trusted Zetasizer DLS expertise