A Household Paint that Kills Germs

CNET News
Michael Kanellos
January 22, 2008

In the future, your countertop could disinfect itself.

Researchers at Rice University and City College of New York have come up with a way to embed silver nanoparticles in vegetable oil-based paint. Early tests show that the material exhibits “efficient antibacterial activity” toward E. coli and Staphylococcus aureus.

Silver’s antibacterial properties have been known since the age of the Roman Empire, but making nano-sized particles (nano particles measure less than 100 billionths of a meter long) and then fixing them in paints and coatings has typically been expensive and time consuming. The Rice and CCNY researchers devised a hydrocarbon soup that in turn helps form raw materials into nano-sized particles.

“We extensively worked on polyunsaturated hydrocarbon chain-containing polymers to devise a novel approach to nanoparticle formation,” said lead author George John, professor of chemistry at CCNY. Technically speaking, the process starts with a paints composed of alkyd resins, which contain a variety of polyunsaturated fatty acids. The resins get cured with exposure to the environment and form a scratch-free surface. Chemically active free radicals are also formed from the fatty acids during this process.

The researchers essentially added metal salts during the drying process and found that the free radicals form nanoparticles out of the metal ions.

“This means that the process is as simple as adding the metal salts to the oils and let the natural process occur, leading to a good dispersion of nanoparticles in the paints,” wrote Pulickel Ajayan, Rice’s Benjamin M. and Mary Greenwood Anderson Professor in Mechanical Engineering and Materials Science, in an email.

The researchers added that the elements in the paint are fairly green and should also last longer than other organic pigment paints.

Killing microbes with green technology has become a growing business. Several companies such as Marrone Organic Innovations and AgraQuest have developed organic pesticides while CleanWell sells a organic hand cleaner.

TyraTech, meanwhile, is working with Kraft on dairy foods that can kill internal pesticides.

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