Research Highlights

Nanoparticles measured using centrifuge

Published online 30 June 2011

Mark Buchanan

The unusual electrical, optical and chemical properties of nanoparticles make them ideal materials in developing technologies ranging from biomedical imaging to solar cells. Even so, industrial applications are hampered by a lack of versatile ways to measure key features of a nanoparticle sample — such as the distribution of particle sizes and masses. Now a team of researchers has demonstrated a powerful new technique that finds such data accurately in one simple step.

The new method — developed by a team including researchers from the King Abdullah University of Science and Technology, Saudi Arabia — dissolves nanoparticles in a solution, which is then centrifuged. The centrifugal force makes particles with different sizes or molecular masses move differently through the solution, providing optical data that can be interpreted.

For demonstration, the team first measured the properties of several standard samples of gold nanoparticles, finding values of particle density and molecular weight within 4% or so of measurements made mathematically. Applied to a tougher challenge — a sample with particle diameters ranging from 4 nm to 9 nm — the method again found the distribution of molecular weights, densities and diameters that closely agree with previously known data. According to the researchers, the technique works with samples smaller than 1 mg.

"As our methodology is simple, rapid, accurate and scalable," says Osman Bakr, a member of the team. "We expect the findings to be useful to anyone interested in the application of nanoparticles."


  1. Carney R., et al. Determination of nanoparticle size distribution together with density or molecular weight by 2D analytical ultracentrifugation. Nature Communications June 7, 2011.  doi: 10.1038/ncomms1338