Size and shape analysis of molecules and particles by Analytical Ultracentrifugation using UltraScan
|Research Area||Materials Science|
|Principal Investigator(s)||Helmut Cölfen|
Analytical Ultracentrifugation(AUC) is a powerful tool to determine size and shape of molecules and particles even if they are present in complex mixtures. Recently, a new multiwavelength UV/Vis absorption detector became available, which can detect the sedimenting sample for up to 800 wavelengths instead of only one. The sedimentation profiles for each detection wavelength allow the analysis of sample size and shape with sophisticated software packages like UltraScan. For the multiwavelength detector, the information content is much higher than for previous detectors since the wavelength dimension is added. Data files for a typical run can be up to several hundred Mb of data, which need to be fitted to adaptive space-time finite element solutions (ASTFEM solutions, [2, 3]) to the Lamm equation of sedimentation and diffusion transport in the analytical ultracentrifuge to extract the size and shape information. The main computation kernel is a divide and conquer non-negative least squares method and the finite element simulations. This is a computationally intensive process. We use a supercomputer to be able to evaluate key experiments from the areas of Medicine, Biophysics, Materials Science and Chemistry to characterize complex samples which fulfil the requirements that 1) they are very important and 2) key information can be obtained about these samples in physiological solution states, which contributes much to the understanding and 3) this key information can only be obtained by multiwavelength AUC. Examples are growth processes of metals or semiconductors with size dependent optical properties, interactions of particles with biomolecules (Nanotoxicology), the early stages of crystallization processes or complex interacting biomolecules, which are relevant for biophysics, biochemistry, molecular biology or molecular medicine.