title: Visualizing the analogy between competitive adsorption and colloid stability to restore lung surfactant function.
abstract: We investigated a model of acute respiratory distress syndrome in which the serum protein albumin adsorbs to an air-liquid interface and prevents the thermodynamically preferable adsorption of the clinical lung surfactant Survanta by inducing steric and electrostatic energy barriers analogous to those that prevent colloidal aggregation. Chitosan and polyethylene glycol (PEG), two polymers that traditionally have been used to aggregate colloids, both allow Survanta to quantitatively displace albumin from the interface, but through two distinct mechanisms. Direct visualization with confocal microscopy shows that the polycation chitosan coadsorbs to interfacial layers of both Survanta and albumin, and also colocalizes with the anionic domains of Survanta at the air-liquid interface, consistent with it eliminating the electrostatic repulsion by neutralizing the surface charges on albumin and Survanta. In contrast, the PEG distribution does not change during the displacement of albumin by Survanta, consistent with PEG inducing a depletion attraction sufficient to overcome the repulsive energy barrier toward adsorption.
authors.affiliation: Department of Chemical Engineering, University of California, Santa Barbara, California, USA.
authors.forename: Ian C
authors.initials: IC
authors.lastname: Shieh
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Waring
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Zasadzinski
mesh_terms: D000327:Adsorption; D000818:Animals; D001688:Biological Products / Q000737:chemistry* / Q000494:pharmacology; D002417:Cattle; D048271:Chitosan / Q000737:chemistry; D003102:Colloids; D018613:Microscopy, Confocal; D011092:Polyethylene Glycols / Q000737:chemistry; D011663:Pulmonary Surfactants / Q000737:chemistry* / Q000494:pharmacology; D012710:Serum Albumin, Bovine / Q000737:chemistry; D013050:Spectrometry, Fluorescence; D013499:Surface Properties
chemical_list: D001688:Biological Products; D003102:Colloids; D011663:Pulmonary Surfactants; D012710:Serum Albumin, Bovine; D011092:Polyethylene Glycols; D048271:Chitosan; C072197:beractant