Applying analytical ultracentrifugation to nanocrystal suspensions.

While applied frequently in physical biochemistry to the study of protein complexes, the quantitative use of analytical ultracentrifugation (AUC) for nanocrystal analysis is relatively rare. Its application in nanoscience is potentially very powerful as it provides a measure of nanocrystal density, size and structure directly in the solution phase. Towards that end, this paper examines the best practices for applying data collection and analysis methods for AUC, geared towards the study of biomolecules, to the unique problems of nanoparticle analysis.

Size-dependent sedimentation properties of nanocrystals.

Centrifugation is an increasingly important technique for nanomaterial processing. Here, we examine this process for gold, cadmium selenide, and iron oxide nanocrystals using an analytical ultracentrifuge. Such data provide an accurate measure of the sedimentation coefficients for these materials, and we find that this parameter has a significant dependence on the size and surface coating.