Scientists have developed antimicrobial steel

Simple processing of stainless steel made its surface also antibacterial

Sergey Vasiliev, N+1

Electrochemical etching of ordinary stainless steel allowed scientists to create complex nanostructures on its surface, unable to damage large mammalian cells, but deadly to bacteria. In the future, this will make it possible to make metal tools and surfaces with antibacterial properties. Julie Champion and her colleagues from the Georgia Institute of Technology presented the novelty in an article published by ACS Biomaterials Science & Engineering (Jang et al., Inhibition of Bacterial Adhesion on Nanotextured Stainless Steel 316L by Electrochemical Etching).

A sample of 316L steel was taken as a basis, which was immersed in an electrolyte and voltage was applied. By varying the parameters and current density, scientists achieved the creation of different surface structures. One option demonstrated good hydrophobic properties – and, unexpectedly for the authors themselves, strong antibacterial. The exact mechanism of this action remains to be determined. In the meantime, scientists suggest that it's all about the numerous bumps and sharp needles with a height of 20-25 nm, which are formed on the steel surface during processing.

Experiments have shown that they successfully cope with both gram-positive (S.aureus) and gram-negative (E.coli) bacteria, although they are completely harmless for mouse fibroblasts. And since this effect is purely mechanical – most likely, steel nanoeedles simply pierce the membranes of bacterial cells – it is difficult to imagine that microbes would somehow develop resistance against it.

The authors note that a similar technological process is widely used to give stainless steel a polished shine, therefore, obtaining "antimicrobial" steel should not be a difficult task for the industry. Moreover, such texturing increases the concentration of chromium and molybdenum at the surface of the material, which increases its corrosion resistance.

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