The elaboration of novel and efficient hydrogel-based materials with antimicrobial properties requires a refined control of their defining physicochemical features, which includes mechanical stiffness, so as to properly mediate their antibacterial activity. In this work, we design hydrogels consisting of polyelectrolyte multilayer films for the loading of T4 and φX174 bacteria-killing viruses, also called bacteriophages. We investigate the anti-adhesion and bactericidal performances of this biomaterial against Escherichia coli, with a specific focus on the effects of chemical cross-linking of the hydrogel matrix which, in turn, mediates the hydrogel stiffness. Depending on the latter and on phage replication features, it is found that the hydrogels loaded with the bacteria-killing viruses make it possible both contactkilling (targeted bacteria are those adhered at the hydrogel surface) and release killing (planktonic bacteria are the targets) with ca. 20% to 80% efficiency after only 4 hours incubation at 25°C, as compared to cases where hydrogels are free of viruses. We further demonstrate the lack of dependence of virus diffusion within the hydrogel and of the maximal viral storage capacity on the hydrogel mechanical properties. In addition to the evidenced bacteriolytic activity of the phages loaded in the hydrogels, the antimicrobial property of the phages-loaded materials is shown to be partly controlled by the chemistry of the hydrogel skeleton and, more specifically, by the mobility of the peripheral free polycationic components, known for their ability to weaken and permeabilize membranes of bacteria, the latter then becoming 'easier' targets for the viruses.

Combination of microbial assays and Single Molecule Force Spectroscopy evidence nano–macro relationship in adhesion properties of E. coli expressing Yad fimbriae. Affinity of Yad fimbriae for xylose is as strong as that for YadC and YadN antibodies.