title: A comparative PM-IRRAS and ellipsometry study of the adsorptive behaviour of bovine serum albumin on a gold surface.
abstract: Polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS) and ellipsometry were used ex situ to investigate adsorption of bovine serum albumin (BSA) on a gold surface, in terms of the adsorption equilibrium and kinetics. The aim of the work was to examine if the two different techniques give similar/complementary results under the same experimental conditions employing the same protein/surface system, and thus validate the use of the techniques for the investigation of protein/surface interactions under the applied experimental conditions, in general. It was found that the adsorption of BSA on gold follows Type I isotherm, which can be described by the Freundlich isotherm. The initial BSA adsorption kinetics was found to be very fast, and the results were modelled using a two-step kinetic model. The first step represents reversible BSA adsorption that yields BSA adsorbed in a native configuration (θ1) that is not thermodynamically stable. The second step represents the irreversible transformation of this protein configuration into a thermodynamically stable surface-adsorbed configuration (θ2). It was found that the θ2/θ1 ratio increased with time. Finally, the comparison of the results obtained by the two techniques showed a very good agreement.
authors: Department of Chemical Engineering, McGill University, 3610 University Street, Montréal, Québec H3A 0C5, Canada.
authors: Mahdi
authors: M
authors: Dargahi
authors: Department of Chemical Engineering, McGill University, 3610 University Street, Montréal, Québec H3A 0C5, Canada. Electronic address: sasha.omanovic@mcgill.ca.
authors: Sasha
authors: S
authors: Omanovic
mesh_terms: D000327:Adsorption; D000818:Animals; D002417:Cattle; D006046:Gold / Q000737:chemistry*; D012710:Serum Albumin, Bovine / Q000737:chemistry*; D013055:Spectrophotometry, Infrared; D013499:Surface Properties
chemical_list: D012710:Serum Albumin, Bovine; D006046:Gold
keywords: Ellipsometry; PM-IRRAS/infrared spectroscopy; Protein adsorption; Serum albumin