AD: Why is it difficult to create a sterile surface?
KL: Common wisdom says you cannot create a sterile surface. Experiments have shown that it's not possible, because when you affix an antiseptic to a surface the antiseptic can't move, and when it's not mobile, it can't rupture the thick bacteria cell membrane.
AD: How does this sterile coating kill the bacteria?
KL: To help the antiseptic become mobile again, we decided to attach it to the end of a long, flexible, thread-like polymer, a common polyvinyl. Attaching the antiseptic to the polymer gives it the mobility to pierce the thick cell membrane and kill the bacteria cell.
AD: What kinds of bacteria can this coating kill?
KL: It can handle the toughest bacteria around, Pseudomonas aeruginosa, which has two membranes that are tough barriers to penetrate. It's also the main cause of death in cystic fibrosis patients. And if this germ-free surface can kill that kind of bacteria, it can kill everything, including bacteria of the genus Staphylococcus and E. coli.
AD: What are the advantages of this kind of germ-killing polymer?
KL: You do not have to apply it. It is already there. It doesn't require people to change their behavior. Also, it is environmentally friendly; no toxic materials are leached out.
AD: What kinds of materials can this germ-killing coating be applied to?
KL: Wood, metal, glass — virtually any material.
AD: How long does this sterile coating last?
KL: That, we don't know. But because the chemicals we use are very stable, we anticipate that it will last for a very long time, from months to years would be my estimate. It's hard to say until you test for that.
AD: What's the next step in terms of getting this coating into commercial use?
KL: We're now in negotiations with a company to scale up the manufacturing process to produce large quantities. This could be ready to go on the market, in say, two years. It will probably first get introduced in hospitals.
AD: Is government approval required to develop this material into a product?
KL: Probably just approval from the Environmental Protection Agency, which would test for toxicity. The basic molecules that we're using are already on the market as a diffusable antiseptic. So, I don't anticipate any obstacles in getting that approval.
AD: What is the scope of future markets for this germ-free surface?
KL: After our paper was published last May [by the National Academy of Sciences], we got calls from every imaginable manufacturer, including people who make covers for school furniture, Boeing and automotive companies. People will probably want to put this coating onto everything. I don't see any limitations.
AD: Could the sterile surface promote the evolution of more powerful or resistant strains of bacteria?
KL: My hunch is that it won't. When bacterial resistance develops, a mutation makes it possible for the bacteria to make more pumps to pump out the antiseptic. This resistance mechanism will probably not work on our surface, because the bacteria's pumps will be overwhelmed by the large number of antiseptic molecules they encounter.
It's America's dirty little secret: 42 percent of men and 25 percent of women don't wash their hands after leaving public restrooms, according to the American Society for Microbiology. Such poor hygienic practices are a critical problem, especially in hospitals. Nearly $5 billion in annual health-care costs in the U.S. stem from infections that patients catch in hospitals, according to the Centers for Disease Control and Prevention. Almost 2 million patients annually contract such infections; some 88,000 die as a result.
But a new sterile coating developed by scientists may change how we fight germs. The coating, which can be applied to a variety of products from urinary catheters to doorknobs, kills bacteria on contact. It was created last year by biologist Kim Lewis of Northeastern University, chemist Joerg Tiller, now at the Freiburg Material Research Center in Germany and chemist Alexander Klibanov of the Massachusetts Institute of Technology.
Lewis claims that the coating kills at least 94 percent of the bacteria that lands on it. Lewis and his colleagues published their discovery in the National Academy of Sciences in May 2001. Since then, they have been in negotiations with various companies to mass produce the coating — a first step to getting this substance into commercial use. American Demographics' Sandra Yin checked in with Lewis to learn more about this germ-killing coating's market potential.