Researchers found that the silver nanoparticles penetrated the paper surface to a depth of more than 1 micrometer (or 1,000 nanometers), resulting in highly stable coatings.

Chemists at Bar-Ilan University in Israel say they have developed and successfully tested "killer paper" coated with silver nanoparticles--each roughly 1/50,000 the width of a human hair--that can fight bacteria such as E. coli and S. aureus.

Described in the American Chemical Society journal Langmuir, researcher Aharon Gedanken tells me that while colloidal silver is already widely used as an antimicrobial agent, what's new about his team's research is the process by which silver nanoparticles are deposited onto paper to develop antimicrobial properties.

The team was able to control both the thickness of the silver coating and particle size while using ultrasonication to attach the nanoparticles to the paper' because the coatings are highly stable and anchored so strongly to the surface, they are long-lasting.

"What is special about the technique is that the nanoparticles are embedded in the surface in such a way that they are not removed by washings," Gedanken says by e-mail. "Our coated textiles were washed 65 cycles by hospital washing machines...and still revealed antibacterial properties."

While the team must now work toward FDA approval in the U.S., Gedanken says the paper could promote longer shelf life as a food packaging material, and perhaps someday reduce or even do away with the practice of preserving foods through radiation, heat treatment, or low temperature storage.