title: Cationic liposome colloidal stability in the presence of guar derivatives suggests depletion interactions may be operative in artificial tears.
abstract: The colloidal stability of cationic 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) liposomes was measured in the presence of guar, carboxymethyl guar, hydroxypropyl guar (HPG), and in mixtures of HPG with boric acid. Carboxymethyl guar induced DOTAP aggregation, presumably by bridging flocculation. The interaction with HPG-borate, an anionic polyelectrolyte with labile charge groups, depended on ionic strength. Without added salt, HPG-borate (pH 9.2) adsorbed on the liposomes and destabilized them. In contrast, in 0.1 M NaCl, HPG-borate did not adsorb onto the liposomes. HPG, HPG-borate, and guar induced depletion flocculation of the liposomes at high polymer concentration. Depletion flocculation may be an important mechanism when HPG is employed in artificial tear formulations.
authors.affiliation: Department of Chemical Engineering, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4L7.
authors.forename: Anil
authors.initials: A
authors.lastname: Khanal
authors.forename: Yuguo
authors.initials: Y
authors.lastname: Cui
authors.forename: Liang
authors.initials: L
authors.lastname: Zhang
authors.forename: Robert
authors.initials: R
authors.lastname: Pelton
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Ren
authors.forename: Howard
authors.initials: H
authors.lastname: Ketelson
authors.forename: James
authors.initials: J
authors.lastname: Davis
mesh_terms: D000838:Anions; D001881:Borates / Q000737:chemistry* / Q000378:metabolism; D003102:Colloids / Q000737:chemistry*; D004573:Electrolytes / Q000737:chemistry* / Q000378:metabolism; D005229:Fatty Acids, Monounsaturated / Q000737:chemistry* / Q000378:metabolism; D005427:Flocculation; D008081:Liposomes; D009883:Ophthalmic Solutions / Q000737:chemistry* / Q000378:metabolism; D011134:Polysaccharides / Q000737:chemistry* / Q000378:metabolism; D000644:Quaternary Ammonium Compounds / Q000737:chemistry* / Q000378:metabolism
chemical_list: D000838:Anions; D001881:Borates; D003102:Colloids; D004573:Electrolytes; D005229:Fatty Acids, Monounsaturated; D008081:Liposomes; D009883:Ophthalmic Solutions; D011134:Polysaccharides; D000644:Quaternary Ammonium Compounds; C519976:hydroxypropyl guar; C070046:1,2-dioleoyloxy-3-(trimethylammonium)propane