Suds turn silver nanoparticles in clothes into duds

DENVER — Life’s bleachable moments may be a death sentence for bacteria-busting silver nanoparticles.

The tiny metal balls that coat some recently manufactured athletic clothing and hospital gowns can crack and crumble when they’re washed in tough detergents that contain bleach or bleach alternatives, researchers reported March 25 at the national meeting of the American Chemical Society. The finding suggests that fabrics toting antibacterial nanoparticles may not stand the test of time – or the laundry cycle.

Silver nanoparticles are commonly used to shield clothes from smelly or infectious bacteria. But scientists know little about what happens to the silver particles over time — neither whether the nanoparticles’ bacteria-repelling powers wane nor whether they release toxic silver ions into the environment.

Researchers led by analytical chemist Denise Mitrano at Empa, the Swiss Federal Laboratories for Materials Science and Technology in St. Gallen, tested how detergents affect nanosilver-coated garb. The researchers found that detergents containing bleach and bleach alternatives caused the nanoparticles to degrade. The detergents probably widen tiny fissures on the particles’ surfaces, causing little chunks to break off, Mitrano says.

Milder detergents had no such effect. But they still washed the particles out of the fabrics over time, possibly enabling release of toxic ions into wastewater.