Christophe Detrembleur and colleagues explain that while stainless steel is prized for its durability, resistance to corrosion and ease of cleaning, it readily collects bacteria over time. The bacteria can form invisible colonies or biofilms – collections of colonies bound tightly to a surface – that spread disease. Existing ways of making stainless steel with an antibacterial surface are complicated, expensive and require the use of potentially toxic chemical substances. The authors sought an easier, "greener" way to make an antibacterial coating for stainless steel.
They describe development of a process for giving stainless steel a coating that killed all E. coli bacteria present within two hours in laboratory tests. It involves applying a layer of a bio-inspired adhesive to the steel, then four alternating layers of a negatively-charged polymer and positively-charged polymer micelles containing silver-based particles, which are highly bactericidal. The process takes only 10 minutes and uses water instead of potentially toxic substances. "This novel water-based approach is convenient, simple and attractive for industrial applications," the researchers say.