Binding of bile salts to an amphiphilic polysulfonate modified with cholesterol moieties

Abstract

A hydrophobically modified polysulfonate bearing a small mole percent (5 mol %) of cholesteryl moieties forms an intermolecularly bridged flower micelle in water, arising from intermolecular associations of the polymer-bound cholesteryl groups. Binding of sodium cholate (SC) to this polymer micelle in water was investigated using 1H NMR spin-spin relaxation time, static light scattering, quasi-elastic light scattering, and fluorescence techniques. The intermolecular association of the polymer-bound cholesteryl groups was disrupted, to some extent, by the addition of SC, resulting in the formation of complexes of the polymer-bound cholesteryl groups and SC. To investigate interactions between the polymer-bound cholesteryl groups and SC, the cholesteryl groups were labeled with a naphthalene moiety. Fluorescence spectra of the naphthalene labels and NMR spin-spin relaxation time data suggested that interactions between the aggregates of the polymer-bound cholesteryl groups and SC occurred below a critical micelle concentration of SC in water.