Colloidal nanoparticles have become important materials in biomedicine, catalysis, and optoelectronics. Their unique nanoscale properties stem from their size (particularly of the inorganic particle core) and surface composition of their organic ligand-shell. Given the polydispersity of nanoparticles, and complex composition, no technique other than Analytical Ultracentrifugation (AUC) has the potential to provide detailed information on the overall particle size, density, molecular weight and aggregation state in solution.
While AUC has become a standard tool for bioscientists to quantitatively study the size, confirmation, and interaction of macromolecules and proteins in solution for many decades, it has not had the same success with nanoparticles. Unlike nanoparticles, most proteins have a well-known partial specific volume, and hence it’s straightforward to convert quantities measured from AUC, such as the sedimentation coefficients, into parameters that provide physical insights into the macromolecule, such as frictional ratio (i.e. shape) and molecular weight.
Recent advancements in the mathematical modeling of the sedimentation boundaries have enabled the parameterization of the sedimentation and diffusion coefficients of all the species detected in solution during centrifugation in terms of their partial specific volume and molecular weight. This advancement opens the door to quantitative investigation of most nanoparticle systems by AUC - without a priori knowledge of their partial specific volume - since most nanoparticles have a constant shape which can be assessed by electron microscopy.
In this tutorial webinar I will introduce some of the latest methods and procedures to analyze nanoparticles in solution with AUC. I will also provide insights on avoiding common experimental challenges that researchers face when studying nanoparticles with the AUC, which may lead to artifacts in the experimental data.