title: Interactions between dialkyldimethylammonium bromides (DXDAB) and sterols--a monolayer study.
abstract: Langmuir monolayers of cholesterol/ergosterol and dialkyldimethylammonium bromides (DXDABs) differing in alkyl chain length-14 (DTDAB), 16 (DHDAB), and 18 (DODAB)-spread at the air/water interface are examined. All the systems investigated are found to be nonideal and miscible. Negative values of the total free energy of mixing, proving film stability in the whole range of compositions and surface pressures, are observed for all the studied mixtures except for DTDAB/cholesterol. The strength of interactions, quantified with DeltaG(Exc) values, was found to be of the same order for mixtures of cholesterol/ergosterol and DHDAB or DODAB. Differences occurring for the mixtures of DTDAB with sterols indicate the affinity of DTDAB to ergosterol in contrast to cholesterol.
authors.affiliation: Department of General Chemistry, Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Kraków, Poland. hac@chemia.uj.edu.pl
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Hac-Wydro
authors.forename: Paweł
authors.initials: P
authors.lastname: Wydro
authors.forename: Patrycja
authors.initials: P
authors.lastname: Dynarowicz-Łatka
mesh_terms: D002784:Cholesterol / Q000737:chemistry*; D004875:Ergosterol / Q000737:chemistry*; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D013499:Surface Properties; D013501:Surface-Active Agents / Q000737:chemistry; D013816:Thermodynamics
chemical_list: D000644:Quaternary Ammonium Compounds; D013501:Surface-Active Agents; C469893:dimethyldidecylammonium chloride; C015831:dimethyldioctadecylammonium; C046417:dihexadecyldimethylammonium; D002784:Cholesterol; D004875:Ergosterol