Prevention of bacterial biofilms onto stainless steel substrates by immobilization of antimicrobial and anti-biofilm biomolecules

Stainless steel is widely used in the daily life in building and food industries as well as in the medical field. However, at long term, bacteria succeed in adhering, proliferating and forming a resistant biofilm on stainless steel. Therefore, surface modification is needed providing metal surface with antibacterial, anti-adhesion and easy cleaning properties. Several biomolecules (antimicrobial peptides, antiadhesion biomolecules and anti-biofilm enzymes) were immobilized on stainless steel thanks to different immobilization techniques. In a first approach, cationic peptides have been embedded in a LBL architecture comprising anti-adhesion biomolecules. In a second approach, small inorganic-binding peptides isolated by phage display technology and recognizing specifically the steel surface were used as linker for antimicrobial peptide immobilization. Finally, antibacterial peptides were covalently grafted onto an organic-polymeric interlayer deposited by plasma. Resulting antibacterial, antiadhesion and anti-biofilm properties were characterized and the advantages of each immobilization technique were documented. The biocidal effect of these surfaces was demonstrated against Gram+/- bacteria. Coated stainless steel surfaces led to 95% reduction of S. epidermidis adhesion vs bare substrate. By combining both antibacterial and anti-adhesion biomolecules, we produced stainless steel surfaces with better cleanability. A biofilm-releasing glycoside hydrolase was also immobilized on the surface and showed to confer anti-biofilm properties to stainless steel. Moreover, we provide valuable insight about the resistance of the coating to close to real life cleaning conditions