New technology stops bacteria sticking to surfaces

There are potential benefits for applications in the food processing and medical industries

Nanoporous alumina repels E. coli cells. Credit: Guoping Feng

A new type of nanoscale surface to which bacteria cannot stick holds promise for applications in the food processing and medical industries.

The technology, developed by researchers from Cornell University and Rensselaer Polytechnic Institute in the US, uses an electrochemical process called anodisation to create nanoscale pores that change the electrical charge and surface energy of a metal surface, which in turn exerts a repulsive force on bacterial cells and prevents attachment and biofilm formation. These pores can be as small as 15nm; a sheet of paper is about 100,000nm thick.

When the anodisation process was applied to aluminum, it created a nanoporous surface called alumina, which proved effective in preventing surrogates of two well-known pathogens, Escherichia coli O157:H7 and Listeria monocytogenes, from attaching, according to a study recently published in the journal Biofouling.

The study also investigated how the size of the nanopores changed the repulsive forces on bacteria.

A cross-section of nanoporous alumina. Credit: Guoping Feng

'It’s probably one of the lowest-cost possibilities to manufacture a nanostructure on a metallic surface,' said Carmen Moraru, associate professor of food science and the paper’s senior author. Guoping Feng, a research associate in Moraru’s lab, is the paper’s first author.

Finding low-cost solutions to limiting bacterial attachments is particularly important for biomedical and food processing applications. 'The food industry makes products with low profit margins,' said Moraru. 'Unless a technology is affordable it doesn’t stand the chance of being practically applied.'

Anodised metals could be used to prevent the build-up of biofilms in biomedical cleanrooms and in equipment parts that are hard to reach or clean, Moraru said.