Cationic liposome colloidal stability in the presence of guar derivatives suggests depletion interactions may be operative in artificial tears.
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.
Khanal
Anil
A
Department of Chemical Engineering, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4L7.
Cui
Yuguo
Y
Zhang
Liang
L
Pelton
Robert
R
Ren
Yuanyuan
Y
Ketelson
Howard
H
Davis
James
J
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
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