Quasielastic Light Scattering Studies of Model Bile Systems

Abstract

Although conventional light scattering techniques have been employed in the study of macromolecules for many years, it has been only in the last decade that measurements of the temporal fluctuations in the scattered intensity have been employed to probe the Brownian movement of macromolecules in solution.¹ By these means the quasielastic light scattering (QLS) technique has provided a rapid, accurate and non-invasive method for measuring the translational diffusion coefficients of macromolecules that far surpasses classical diffusion methods. The diffusion coefficient is a parameter that in general will depend on the size of the macro-molecule, and on the thermodynamic and hydrodynamic interaction between the macromolecules. However, even at relatively high macro-molecular concentrations, the interaction effects are often found to be weak and thus the diffusion coefficient can be interpreted directly to provide the hydrodynamic radius of the macromolecule.² In addition, the QLS technique can also provide information on macromolecular polydispersity, and is therefore quite suited for the study of aggregating systems where polydispersity is often sizeable.