IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Biomaterials Wednesday Sessions
       Session BI+SS-WeM

Paper BI+SS-WeM4
Buildup Mechanism for Hyaluronic Acid/polysine Films onto a Solid Interface

Wednesday, October 31, 2001, 9:20 am, Room 102

Session: Biological Interface & Surface Science
Presenter: J.C. Voegel, INSERM U424, France
Authors: C. Picart, INSERM U424, France
Ph. Lavalle, INSERM U424, France
F.J.G. Cuisinier, INSERM U424, France
P. Schaaf, Institut Charles Sadron (CNRS) Strasbourg, France
J.C. Voegel, INSERM U424, France
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The formation of a new kind of biocompatible films based on Poly-L-Lysine and Hyaluronic Acid (PLL/HA) by alternate deposition of PLL and HA was investigated. It is shown that the driving force of the buildup process appears, as for "convential" polyelectrolyte multilayer systems, to be the alternate overcompensation of the surface charge after each PLL and HA deposition. The construction of (PLL/HA) films appears to take place over two buildup regimes. The first regime is characterized by the formation of isolated islands dispersed on the surface and which grow both by addition of new polyelectrolytes on their top and by mutual coalescence of the islands. The second regime sets in once a continuous film is formed at the after the 8th bilayer deposition in our working conditions. QCM measurements at different frequencies evidences a viscoelastic behavior of the films which have a shear viscosity of the order of 0.1 Pa.s. During this second regime the mass of the multilayer film increases in an exponential rather than in a linear way. This exponential growth is explained the diffusion of free PLL chains into the interior of the film when it is brought in contact with a PLL solution and by the diffusion out of the film of a fraction of these free chain followed by their interactions with HA chains at the outer limit of the multilayer when the film is further brought in contact with a HA solution. The diffusion of free PLL chains into the film is also found to be accompanied by an expulsion of water out of the film. This new kind of biocompatible film incorporating a natural polymer of the extracellular matrix and a widely used polypeptide makes it a potential candidate for cell-targeted action and for the coating of different types of surfaces, such as implants or capsules, in order to mimic a natural extracellular gel.