title: Mixtures of mucin and oppositely charged surfactant aggregates with varying charge density. Phase behavior, association, and dynamics.
abstract: The nonionic surfactant Tween80 is a commonly used excipient in drug formulations containing an active substance with low aqueous solubility. Model drug vehicles with varying charge density were obtained by mixing Tween80 (PS-80) with the cationic surfactant Tetradecyltrimethylammonium chloride (TTAC), thus forming mixed micelles. The micelles were mixed with the negatively charged polyelectrolyte mucin, which is a component in the protective mucus layer covering epithelial cell linings. Depending on the composition of the mixture, complex-formation could be followed by precipitation. Using X-ray diffraction, it was found that the precipitate contained a lamellar phase with properties sensitive to the proportion of PS-80. Higher amounts of PS-80 were found to oppose phase separation. Further analysis in the one-phase region, or alternatively of the supernatant of two-phase samples, by (1)H NMR, HPLC, and diffusion measurements with PGSE-NMR led to the conclusions that at low proportion of PS-80 aggregates composed of mixed (PS-80 and TTAC) micelles and mucin were formed, whereas increased concentrations of PS-80 favored the dissolution of the precipitate and limited the interactions between mixed micelles and the polymer.
authors.affiliation: Physical Chemistry 1, Center for Chemistry and Chemical Engineering, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden. geraldine.lafitte@fkem1.lu.se
authors.forename: Géraldine
authors.initials: G
authors.lastname: Lafitte
authors.forename: Krister
authors.initials: K
authors.lastname: Thuresson
authors.forename: Olle
authors.initials: O
authors.lastname: Söderman
mesh_terms: D000818:Animals; D002412:Cations; D004058:Diffusion; D005753:Gastric Mucosa / Q000378:metabolism; D008823:Micelles; D008956:Models, Chemical; D009077:Mucins / Q000737:chemistry*; D011108:Polymers; D011136:Polysorbates / Q000737:chemistry*; D000644:Quaternary Ammonium Compounds / Q000737:chemistry; D012995:Solubility; D013501:Surface-Active Agents / Q000737:chemistry*; D013552:Swine; D050337:Trimethyl Ammonium Compounds; D014961:X-Ray Diffraction
chemical_list: D002412:Cations; D008823:Micelles; D009077:Mucins; D011108:Polymers; D011136:Polysorbates; D000644:Quaternary Ammonium Compounds; D013501:Surface-Active Agents; D050337:Trimethyl Ammonium Compounds; C009410:tetradecyltrimethylammonium