Principles of laser light-scattering spectroscopy: Applications to the physicochemical study of model and native biles
We present a nonmathematical treatment of the theoretical and experimental aspects of modern laser light-scattering techniques. We also describe the design of a "home-built" laser light-scattering apparatus used in the authors' laboratory for the physicochemical study of model and native biles. These powerful techniques provide nonperturbing measurements of the sizes, polydispersities and, in suitable cases, concentrations and shapes of simple micelles, mixed micelles, vesicles and large proteins in bile. the sizes of these aggregates (10 to 2,000 A) fall within limits resolvable by laser light and are conventionally expressed as mean hydrodynamic radii, Rh. Static light-scattering measurements of biliary lipid aggregates provide molecular weights and important information concerning particle shape, whereas quasielastic (also referred to as dynamic) light-scattering measurements assess particle sizes and polydispersities. Under favorable circumstances, quasielastic light scattering allows simultaneous determinations of sizes and concentrations of coexisting particle populations. The use of laser light-scattering technology in solving the solution properties and the physicochemical structures of model and native biles is detailed. In view of the extraordinarily diverse backgrounds of researchers in the gallstone field (e.g., internists, surgeons, biochemists, physicists), we believe that the present article (which relies heavily on graphical representations) will afford a better understanding of the usefulness and limitations of laser light-scattering techniques, particularly in their applications to the study of bile.