The role of the interplay between polymer architecture and bacterial surface properties on the microbial adhesion to polyoxazoline-based ultrathin films

Surface platforms were engineered from poly(L-lysine)-graft-poly(2-methyl-2-oxazoline) (PLL-g-PMOXA) copolymers to study the mechanisms involved in the non-specific adhesion of Escherichia coli (E coli) bacteria Copolymers with three different grafting densities alpha (PMOXA chains/Lysine residue of 009 033 and 0 56) were synthesized and assembled on niobia (Nb2O5) surfaces PLL-modified and bare niobia surfaces served as controls To evaluate the impact of fimbriae expression on the bacterial adhesion the surfaces were exposed to genetically engineered E coli strains either lacking or constitutively expressing type 1 fimbriae The bacterial adhesion was strongly influenced by the presence of bacterial fimbriae Non-fimbriated bacteria behaved like hard charged particles whose adhesion was dependent on surface charge and ionic strength of the media In contrast bacteria expressing type 1 fimbriae adhered to the substrates independent of surface charge and ionic strength and adhesion was mediated by non-specific van der Waals and hydrophobic interactions of the proteins at the fimbrial tip Adsorbed polymer mass average surface density of the PMOXA chains and thickness of the copolymer films were quantified by optical waveguide lightmode spectroscopy (OWLS) and variable-angle spectroscopic ellipsometry (VASE) whereas the lateral homogeneity was probed by time-of-flight secondary ion mass spectrometry (ToF-SIMS) Streaming current measurements provided information on the charge formation of the polymer-coated and the bare niobia surfaces The adhesion of both bacterial strains could be efficiently inhibited by the copolymer film only with a grafting density of 033 characterized by the highest PMOXA chain surface density and a surface potential close to zero (C) 2010 Elsevier Ltd All rights reserved