Protein adsorption onto auto-assembled polyelectrolyte films

We investigate the adsorption processes of a series of positively and negat ively charged proteins onto the surface of polyelectrolyte multilayers. We find that proteins strongly interact with the polyelectrolyte film whatever the sign of the charge of both the multilayer and the protein. When the ch arges of the multilayer and the protein are similar, one usually observes t he formation of protein monolayers which can become dense. We also show tha t when the protein and the multilayer become oppositely charged, the adsorb ed amounts are usually larger and the formation of thick protein layers ext ending up to several times the largest dimension of the protein can be obse rved. Finally, we find that proteins are mainly adsorbed in a strong way on polyelectrolyte multilayers and protein surface diffusion is strongly sugg ested. Our results confirm that electrostatic interactions play an importan t role in polyelectrolyte multilayer/protein interactions.