A nanoscale surface that bacteria can not stick to holds promise for the food processing industry

Anodized metal could also have marine applications, such as keeping ship hulls free of algae.

The technology, created by researchers from Cornell University and Rensselaer Polytechnic Institute, uses an electrochemical process called anodization to create nanoscale pores that change the electrical charge and surface energy of a metal surface.

This exerts a repulsive force on bacterial cells and prevents attachment and biofilm formation. Surface criteria interaction calculated with the extended Derjaguin Landau Verwey­Overbeek (XDLVO) theory indicated less attachment and biofilm formation is due to a synergy between electrostatic repulsion and surface effective free energy, said the researchers.

Applying the process: When the anodization process was applied to aluminum, it created a nanoporous surface called alumina, which prevented E.coli ATCC 25922 and Listeria innocua from attaching. The team told they are hoping to find industrial partners to test and validate the technology in actual processing settings.

Carmen Moraru, associate professor of food science at Cornell University, said the principle could be applied to a variety of surfaces, including walls, floors and conveyor belts. The surfaces will have an electrical charge that enables them to electrostatically repel bacteria, but there is no actual electricity going through them. Most surfaces (natural or synthetic) do have electrostatic charges.

Anodized metals could be used to prevent build­ups of biofilms, which are hard to remove pathogens that get stuck on machinery and other surfaces in food manufacturing plants.

They form a tough surface skin that resist conventional commercial washing and sanitizing methods, resulting in lowered shelf life of products and potential consumer illness.

Forming of nanoscale pores: Anodization is an electrochemical process, in which the aluminum part is immersed in an acidic bath together with an electrode,” said Borca­Tasciuc, who was the anodization expert of the team.

When current is applied between the part and the electrode, oxygen ions from the solution start reacting with the aluminum surface, forming an oxide layer. The diameter and depth of these pores depend on anodization conditions, such as chemical composition of the bath or applied voltage.

Anodized metal could also have marine applications, such as keeping ship hulls free of algae.

Future work will investigate the repulsive effect of these surfaces on other bacteria, and the use of other anodized materials for this purpose.

Source: http://www.news.cornell.edu/stories/2015/01/new-tech-application-keeps-bacteria-sticking-surfaces