Bacterial adhesion capacity of protein-terminating polyelectrolyte multilayers

Bacterial adhesion on material surfaces can be reduced by different type of coatings. In our study a silica surface on which polyelectrolyte multilayers were formed, with various proteins being the terminating layer, was used as a material surface. We examined three different types of proteins: bovine serum albumin (BSA), lysozyme and glucanase. Adhesion experiments were performed with two bacterial strains: Escherichia coli and Pseudomonas aeruginosa. In order to characterize the surface prior to bacterial adhesion, surface roughness and hydrophobicity were determined by profilometry, atomic force microscopy (AFM) and tensiometry, whereas the surface charge was estimated by zeta potential measurements of silica particles covered with polyelectrolyte multilayers and proteins. The extent of adhered bacteria was examined using scanning electron microscopy (SEM). It was confirmed that in the case where lysozyme was the outermost layer the lysis takes place, whereas in the case of BSA and glucanase specific protein-bacteria interactions are dominant. We showed that the adhesion strongly depends on the protein specificity and the surface physical properties do not play the key role in the adhesion process.