About a million implanted medical devices are infected each year with MRSA and other bacterial species. University of Michigan researchers found that a coating of zinc oxide nanopyramids disrupts the growth of methicillin-resistant Staphylococcus aureus (MRSA), reducing the film on treated materials by over 95 percent.

This image shows a pacemaker lead with a coating of nanoscale zinc oxide pyramids. These pyramids prevent MRSA from colonizing coated surfaces well.
(Credit: Steve Alvey, Michigan Engineering)

If the nanoparticles are shaped like a pyramid with a hexagon-shaped base, they are very effective at preventing an enzyme called beta-galactosidase from breaking down lactose into the smaller sugars glucose and galactose, which the bacteria use for fuel.

To explore the concept of an antibacterial coating, Kotov's group covered some pegs with the nanopyramids and then VanEpps' team stuck them into a substance that would allow bacteria to grow. The researcher evaluated four species of bacteria on coated and uncoated pegs—two staphylococcal species (including MRSA), one species that causes pneumonia and E. coli.

After 24 hours of growth, the number of viable staphylococcal cells recovered from the coated pegs was 95 percent less than those from the uncoated pegs. The pneumonia and E. coli species were less susceptible to the nanoparticles.

"While the coating was unable to completely eradicate all staphylococcal cells, this dramatic reduction could likely enable antibiotic treatments to succeed or simply allow the human immune system to take over without the need for antibiotics," said J. Scott VanEpps, a clinical lecturer and research fellow in the U-M Medical School's department of emergency medicine.