title: Friction force spectroscopy of β- and κ-casein monolayers.
abstract: Friction force spectroscopy (FFS) has been applied to study the tribological properties of β- and κ-casein layers on hydrophobic substrates in aqueous solutions. Nanometer-sized imaging tips were employed. This allowed exerting and determining the high pressures needed to remove the layers and registering the topographic evolution during this process. Both β- and κ-casein layers showed similar and not particularly high initial frictional responses (friction coefficient of ∼1 when measured with a silicon nitride tip). The pressures needed to remove the layers were of the same order of magnitude for both proteins, ∼10(8) Pa, but slightly higher for those composed of β-casein. The technique has also shown to be useful in studying the two-dimensional lateral diffusion of the proteins and the wear on the layers they form.
authors.affiliation: Biomedical Laboratory Science and Technology, Faculty of Health and Society, Malmoe University, 20506 Malmoe, Sweden. javier.sotres@mah.se
authors.forename: Javier
authors.initials: J
authors.lastname: Sotres
authors.forename: Olof
authors.initials: O
authors.lastname: Svensson
authors.forename: Thomas
authors.initials: T
authors.lastname: Arnebrant
mesh_terms: D002364:Caseins / Q000737:chemistry*; D017276:Friction; D018625:Microscopy, Atomic Force; D013057:Spectrum Analysis / Q000379:methods*; D013499:Surface Properties
chemical_list: D002364:Caseins