Methods for Measuring Molecular Diffusion Coefficients of Large Proteins and Bio-nanopartilces

Abstract

Molecular diffusion coefficients are important physical (transport) properties for designing various separation processes such as chromatography and drying. They are also used for understanding the size of molecules. Although several methods can be used for determining the molecular diffusion coefficient D_m, the D_m values for large (modified) proteins, DNA and bio-nanoparticles are not readily available. In this study, D_m values of PEGylated proteins of various molecular weights were measured by using the Taylor dispersion analysis (TDA) method and dynamic light scattering (DLS). Both methods provided very similar D_m values. However, as each method has its own characteristics, limitations and precautions, it is recommended to use both methods as complimentary methods for obtaining reliable D_m values.