Scientists work toward a long-lasting antibacterial stainless steel coating
August 2012 - When admitted to a hospital, patients expect cleanliness in an environment where wounds and weakened immune systems are susceptible to volatile radicals. Diners have similar expectations when seated to a meal—utensils, plates and the preparation surfaces food touches should be clean. Researchers in Belgium are breaking down possible antibacterial coatings to help ensure there are no hidden dangers on a hospital tray or plate.
Currently, scientists have formulated a spray-on coating that kills bacteria but must be reapplied periodically because it wears off. Researchers face many challenges to formulate an antibacterial solution that not only will be long-lasting but also can be fabricated by manufacturers. “Currently, the antibacterial effect is lost once heat from welding is applied,” says Jean Lasar, head of communications and marketing at Aperam in Luxembourg, a global supplier of stainless steel as well as electrical steel and nickel alloys.
According to Lasar, because only short-term solutions currently are available in a sprayable form, researchers have further to uncover. “[The coating’s effects on raw material] will still be a concern for steelmakers that sell coils that later have to be formed and assembled,” Lasar says.
Researchers have been working on an important consortium called “Biocoat” since 2006 at the University of Liège in Belgium, headed by Christophe Detrembleur, senior research associate at the Center for Education and Research on Macromolecules. Industrial partner ArcelorMittal wants “to open new application fields for stainless steel in order to target novel advanced products while considering industrial constraints,” including cost, durability and environmental footprint, Detrembleur says.
Contamination of stainless steel surfaces by bacteria is an especially important concern for those in the health sectors and in areas such as the household and commercial kitchens.
Implications for metals
Detrembleur says researchers “have made substantial progress, and we have developed a new product that is even simpler to apply and greener.
“A green and bio-inspired process to afford durable anti-biofilm properties,” was published in Langmuir, an interdisciplinary scientific journal and explains the process further.
“We have developed a ready-to-use aqueous solution that contains the functional polymer required for the adhesion to support and also grafting of active biomolecules (enzymes and peptides),” Detrembleur says. He explains researchers coat the substrate with the solution and then graft the active biomolecules by dipping the modified substrate into the aqueous solution of the biomolecules.
As research continues, scientists are keeping in mind the importance of creating the simplest possible process to ensure affordability and accessibility. “Our final goal is to accelerate the time to market of the products and processes,” he adds.
By developing water-based solutions with almost no toxic organic solvents, scientists want the ability to either coat or spray the solution to stainless steel. According to Lasar, the durability of the solution must be tested by different markets. He also notes the importance of testing when working with new solutions. Every solution has to be assessed throughout a long period of time, he explains, to ensure safety.
What might seem to yield positive results immediately may turn out to be “detrimental to human beings in the long-term,” Lasar says. It affects not only consumers using the solution-coated equipment but also the manufacturers fabricating treated stainless steel components.
“Antibacterial polymers are, for me, very important because they can be [strongly anchored] to the substrate and are very stable compared to enzymes and peptides. We are putting a lot of effort in this direction,” Detrembleur says, noting developing eco-friendly products is also an important factor in the overall process.
Recycling the uncoated product once solutions wear off will lessen the environmental footprint left by the solution. Detrembleur says although researchers are getting closer to their goals, there is still much progress needed to prolong the effectiveness and durability of the coating.
Once available, Lasar expects industry demand will follow. Interest in a workable solution extends across borders. The solution will be of interest “for all countries where hygiene and cleanliness,” are of importance, Lasar says. MM