Synthetic Rubber Kills Germs On Contact

SAN FRANCISCO, March 27 — The first synthetic rubber that kills bacteria and other pathogenic organisms on contact was described here today at the 219th national meeting of the American Chemical Society, the world’s largest scientific society. The material — whose killing power is renewable — proved effective in laboratory tests against Staphylococcus aureus and other major sources of hospital infections. The study was presented by Shelby Davis Worley, Ph.D., a professor of chemistry at Auburn University in Auburn, Ala.

Worley says the new material — the first antimicrobial rubber — uses a different mechanism to fight infection than conventional coatings and protective plastics. In laboratory tests, it killed viruses and fungi, as well as bacteria. Worley believes this will be especially helpful for patients who are immunocompromised, including transplant recipients and people with cancer or AIDS. (These patients are at increased risk for deadly infections due to their weakened immune systems.)

Condoms made of the new rubber could help prevent the spread of sexually transmitted diseases, says Worley. The material could also be used in medical supplies and devices, including surgical gloves, aprons and catheters, as well as consumer products: beverage and food containers, lids and seals, and babies’ bottles, nipples and pacifiers.

Antimicrobial protection has long been imparted by coating the surface of a material with a liquid or powder disinfectant. More recently, antimicrobial plastics have been used in consumer products such as toothbrushes, mattress pads and children’s toys.

Antimicrobial plastics are composed of polymers mixed with special disinfectants. The plastic slowly releases the disinfectant over time, killing pathogens that come in contact with its surface. When the disinfectant runs out, the plastic permanently looses its disease-fighting ability.

Worley’s technology introduces a chemical structure called an N-halamine into the polystyrene molecules (which provide rigidity) present in a variety of synthetic rubber materials. N-halamines contain a receptor that binds chlorine atoms. The pathogen is killed when it comes in contact with the surface of the rubber, where it is exposed to chlorine.

Although the rubber loses its ability to fight pathogens once the chlorine atoms are used up, this feature can be renewed simply by exposing the rubber to bleach, which provides the missing chlorine atoms. Rubber formulas can be given enhanced disease-fighting power by adding more N-halamine groups to their structure, Worley says.

Based on preliminary laboratory studies, the researcher believes that his rubber will kill microorganisms more quickly and more efficiently than antimicrobial plastics.

N-halamines have already been used to create antimicrobial plastic, which disinfects water in filter systems, and antimicrobial clothing, which protects agricultural workers from pesticide exposure. Worley has applied for a patent for antimicrobial rubber, which he believes may reach the consumer market in a few years. Halosource Corporation of Seattle, Wash., has purchased the process to create antimicrobial plastic, clothing and rubber containing N-halamines.

Shelby Davis Worley, Ph.D., is Professor of Chemistry in the Department of Chemistry at Auburn University in Auburn, Ala.