Zosteric acid and salicylic acid bound to a low density polyethylene surface successfully control bacterial biofilm formation

The active moieties of the anti-biofilm natural compounds zosteric (ZA) and salicylic (SA) acids have
been covalently immobilized on a low density polyethylene (LDPE) surface. The grafting procedure
provided new non-toxic eco-friendly materials (LDPE-CA and LDPE-SA) with anti-biofilm properties
superior to the conventional biocide-based approaches and with features suitable for applications
in challenging fields where the use of antimicrobial agents is limited. Microbiological investigation
proved that LDPE-CA and LDPE-SA: (1) reduced Escherichia coli biofilm biomass by up to 61% with
a mechanism that did not affect bacterial viability; (2) significantly affected biofilm morphology,
decreasing biofilm thickness, roughness, substratum coverage, cell and matrix polysaccharide
bio-volumes by >80% and increasing the surface to bio-volume ratio; (3) made the biofilm more
susceptible to ampicillin and ethanol. Since no molecules were leached from the surface, they
remained constantly effective and below the lethal level; therefore, the risk of inducing resistance
was minimized.