Mary Nora Dickson, University of California, Irvine
A scalable biomimetic antibacterial polymer surface
Written by Devesh Mistry
Biofilms form on surfaces when bacteria grow and emit a slime. This slime makes it difficult to mechanically remove the bacteria and difficult to kill the bacteria using antibacterials. Nano-silver is one technology currently applied to surfaces which kills bacteria; however, as Mary Nora Dickson of the University of California, Irvine, highlighted, bacteria can develop a resistance to the nano-silver.
The wings of cicada and dragonflies are known to be antibacterial. This is achieved by a nanostructure of sharp pillars which cause bacterial cells to rupture. By nano imprinting a poly(methyl methacrylate) substrate with an array of features typically 20-200 nm in size, Dickson has been able to replicate such structures but on an industrial scale. Tests show that a range of different bacterial cells cannot survive on this surface as they appear to conform to the structure leading to an increase in internal pressure followed by cell rupture. SEM images show how the cells of e. coli appear deflated and have adopted the nanostructure.
One application Dickson is currently pursuing is using the structure on medical devices, specifically on artificial corneas. In this application, the structures have the additional benefit of antireflective properties due to a modification of the surface refractive index.