FLUORESCENCE EVIDENCE FOR FORMATION OF A HYALURONATE ION DODECYLTRIMETHYLAMMONIUM BROMIDE COMPLEX

Structural changes of the complex formed by the polysaccharide hyaluro nic acid, as its salt, partially modified by a covalently bound fluore scence probe, 4-fluoro-7-nitrobenz-2-oxa-1,3-diazole, and dodecyltrime thylammonium bromide, were observed by measuring fluorescence depolari zation with 0.175 M NaBr as a function of surfactant concentration. Va lues of depolarization change significantly between 2.0 and 10.0 mM su rfactant. The critical micelle concentrations of the surfactant in 0.1 75 M NaBr in the absence and presence of the polymer are in the surfac tant concentration range at which fluorescence polarization changes. F ormation of the surfactant-polymer complex at high salt concentration is consistent with appearance of free micelles, which associate with t he anionic polymer. (C) 1994 Academic Press, Inc.