Nanofunctionalised sol-gel surface coatings for biofilm prevention

Speaker:

Rikke Louise Meyer Postdoctoral Researcher, University of Aarhus

Many bacteria attach to surfaces in their environment, which makes them difficult to remove and less susceptible to antibiotics and cleaning agents. Bacteria on surfaces where food is handled can thus cause food spoilage and pose a risk to consumer safety. Much effort is therefore being put into implementing surface treatments and cleaning procedures that effectively reduce the amount of bacteria attaching to surfaces. Nanotechnology is providing new ways to manipulate the structure and chemistry of surfaces to make them unattractive for bacterial settlement. In this study, we coated stainless steel surfaces with nanostructured glass ceramics prepared by the sol-gel method. The coating system was formulated with organic modified alkoxysilanes and functionalized with surface orientating silicones, to achieve a smooth surface topography. We found that the low roughness of sol-gel coated surfaces reduced bacterial adhesion. Furthermore less protein adsorbed to the surfaces compared to steel and during cleaning with acid and alkaline solutions, more bacteria were removed. This suggests that the bacteria present did not adhere strongly to the surface. We furthermore functionalised the sol-gel coatings with Cu, Ag, and ZnO nanoparticles. Particularly ZnO nanoparticles decreased the amount of bacteria adhering to the surfaces substantially – both when tested with model organisms and with mixed cultures enriched from pork. Compared to stainless steel, the amount of bacteria attaching to ZnO functionalised sol-gel was two orders of magnitude less. Sol-gel coatings proved useful to reduce surface roughness below the level where it affects bacterial adhesion, and the coatings provided a versatile platform for functionalisation with nanoparticles covalently bound in the coating.