Bacterial adhesion at synthetic surfaces

A systematic investigation into the effect of surface chemistry on bacteria l adhesion was carried out. In particular, a number of physicochemical fact ors important in defining the surface at the molecular level were assessed for their effect on the adhesion of Listeria monocytogenes, Salmonella typh imurium, Staphylococcus aureus, and Escherichia coli, The primary experimen ts involved the grafting of groups varying in hydrophilicity, hydrophobicit y, chain length, and chemical functionality onto glass substrates such that the surfaces were homogeneous and densely packed with functional groups. A ll of the surfaces were found to be chemically well defined, and their meas ured surface energies varied from 15 to 41 mJ.m(-2). Protein adsorption exp eriments were performed with H-3 labelled bovine serum albumin and cytochro me c prior to bacterial attachment studies. Hydrophilic uncharged surfaces showed the greatest resistance to protein adsorption; however, our studies also showed that the effectiveness of poly(ethyleneoxide) (PEO) polymers wa s not simply a result of its hydrophilicity and molecular weight alone. The adsorption of the two proteins approximately correlated with short-term ce ll adhesion, and bacterial attachment for L. monocytogenes and E. coli also correlated with the chemistry of the underlying substrate. However, for S. aureus and S. typhimurium a different pattern of attachment occurred, sugg esting a dissimilar mechanism of cell attachment, although high-molecular-w eight PEO was still the least-cell-adsorbing surface. The implications of t his for in vivo attachment of cells suggest that hydrophilic passivating gr oups may be the best method for preventing cell adsorption to synthetic sub strates provided they can be grafted uniformly and in sufficient density at the surface.