title: Spread Films of Human Serum Albumin at the Air-Water Interface: Optimization, Morphology, and Durability.
abstract: It has been known for almost one hundred years that a lower surface tension can be achieved at the air-water interface by spreading protein from a concentrated solution than by adsorption from an equivalent total bulk concentration. Nevertheless, the factors that control this nonequilibrium process have not been fully understood. In the present work, we apply ellipsometry, neutron reflectometry, X-ray reflectometry, and Brewster angle microscopy to elaborate the surface loading of human serum albumin in terms of both the macroscopic film morphology and the spreading dynamics. We show that the dominant contribution to the surface loading mechanism is the Marangoni spreading of protein from the bulk of the droplets rather than the direct transfer of their surface films. The films can be spread on a dilute subphase if the concentration of the spreading solution is sufficient; if not, dissolution of the protein occurs, and only a textured adsorbed layer slowly forms. The morphology of the spread protein films comprises an extended network with regions of less textured material or gaps. Further, mechanical cycling of the surface area of the spread films anneals the network into a membrane that approach constant compressibility and has increased durability. Our work provides a new perspective on an old problem in colloid and interface science. The scope for optimization of the surface loading mechanism in a range of systems leading to its exploitation in deposition-based technologies in the future is discussed.
authors.affiliation: Institut Laue-Langevin , 71 avenue des Martyrs, CS 20156, 38042 Grenoble, Cedex 9, France.
authors.forename: Richard A
authors.initials: RA
authors.lastname: Campbell
authors.affiliation: Research School of Chemistry, Australian National University , Canberra, ACT 0200, Australia.
authors.forename: Joo Chuan
authors.initials: JC
authors.lastname: Ang
authors.affiliation: Institut Laue-Langevin , 71 avenue des Martyrs, CS 20156, 38042 Grenoble, Cedex 9, France.|Department of Chemistry, University of Reading , P.O. Box 224, Reading RG6 6AD, U.K.
authors.forename: Federica
authors.initials: F
authors.lastname: Sebastiani
authors.affiliation: Institut Laue-Langevin , 71 avenue des Martyrs, CS 20156, 38042 Grenoble, Cedex 9, France.|Institute of Chemistry, Eötvös Loránd University , Budapest 112, P.O. Box 32, H-1518 Hungary.
authors.forename: Andrea
authors.initials: A
authors.lastname: Tummino
authors.affiliation: Research School of Chemistry, Australian National University , Canberra, ACT 0200, Australia.
authors.forename: John W
authors.initials: JW
authors.lastname: White
mesh_terms: D000388:Air; D006801:Humans; D010316:Particle Size; D012709:Serum Albumin / Q000737:chemistry*; D013499:Surface Properties; D014867:Water / Q000737:chemistry*
chemical_list: D012709:Serum Albumin; D014867:Water