AVS 47th International Symposium
    Biomaterial Interfaces Tuesday Sessions
       Session BI-TuM

Paper BI-TuM8
Protein Adsorption on Self-assembled Polyelectrolyte Multilayer Films

Tuesday, October 3, 2000, 10:40 am, Room 202

Session: Protein-Surface Interactions
Presenter: P. Schaaf, Institut Charles Sadron, France
Authors: G.D. Ladam, Institut Charles Sadron, France
F.J.G. Cuisinier, Federation de Recherche "Odontologie", France
G. Decher, Institut Charles Sadron, France
J. Voegel, Federation de Recherche "Odontologie", France
P. Schaaf, Institut Charles Sadron, France
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Alternating polyelectrolyte films were constructed by the sequential adsorption of poly(allylamine hydrochloride) (PAH) and polystyrenesulfonate (PSS) onto a silica surface. The film build-up and the further adsorption of proteins (human serum albumin (HSA), ribonuclease A, lysozyme, alpha-lactalbumine, myoglobine) were followed in situ versus time by means of scanning angle reflectometry. We investigated first the influence of the isoelectric point of the proteins on their adsorption onto positive (PAH ending) and negative (PSS ending) multilayers. At a protein concentration of 0.25mg/ml at pH 7.4 and in the presence of Tris HCl 10-2M, 0.15M NaCl buffer, all proteins adsorbed on both positive and negative polyelectrolyte films with thicknesses varying from the monolayer or less, up to thicknesses equivalent to at least 4 protein layers. Thick protein layers were observed when proteins and films were oppositely charged. The adsorption of HAS onto both films was investigated as a function of the protein concentration and the NaCl concentration of the adsorbing solution. It was found that on PSS ending multilayers exhibiting a similar charge as albumin, the proteins still adsorb but only a monolayer can be reached. On the other hand, on PAH ending multilayers thick protein films are observed. The adsorbed amount depends also critically on the NaCl concentration of the adsorbing solution. Desorption experiments were also performed and depending on the salt concentration of the rinsing solution one can observe no desorption or partial desorption (up to 50% of the adsorbed amount). A microsocopic model will be discussed trying to explain these experimental findings.