Shower curtains that repel mildew? Sweaty socks that don't smell? Many of our daily bouts with common bacteria may be over, thanks to a research team led by Chemistry Department Chair Lanny Liebeskind.
The team has perfected a solution that will stay on any surface for months-despite repeated washings-and that prevents bacteria from growing on those surfaces.
The research project began about 18 months ago when Liebeskind was approached by an entrepreneurial acquaintance who needed some chemical expertise. "This was a real seat-of-the-pants project," said Liebeskind, who asked colleagues Gary Allred and Eric Nickel, two postdoctoral associates, to join him in developing the substance.
Issues regarding marketability, manufacturing and shipping were foreign to Liesbeskind, a basic scientist. The great majority of his research efforts have been in inventing new chemical reactions that ultimately help pharmaceutical companies develop new drugs. "I'm not used to projects with such immediate commercial potential," he admitted.
Existing research in the field of antimicrobial agents first helped Liesbeskind and Allred better understand antimicrobials and surface-bonding materials. Their starting point-compounds known as quaternary ammonium salts-are found in many over-the-counter antiseptic lotions and are known to have antimicrobial activity and surface-bonding properties, explained Allred. "But without the silated bonding portion, they have no surface durability."
The two then familiarized themselves with patent, science and technical literature on bonding agents, said Liebeskind. Molecules can be bound to a surface through a silane-coupling process. The coupling occurs only when the agent is mixed with water, and if applied to a surface immediately, it will adhere through several washings.
But storage time for that solution wasn't very long. If the solution was not used immediately after mixing with water, it formed a very large molecule called a polymer-and basically became an unusable white mass in the bottom of the container.
To increase the commercial value of the antimicrobial agent, the researchers needed an agent that could be activated by water and stored and shipped in water without polymerizing. Usually such an agent needs to be stored and shipped in methanol-a flammable and toxic substance that poses safety problems for consumers.
Liebeskind and Allred proposed adding a second molecule to the antimicrobial agent that would give the silane-coupling portion of the molecule "something else to do than react to itself," explained Liebeskind. With that refinement, the agent became completely water-based, safe and nontoxic.
To test the durability of their new formulation, Allred applied the agent to his home shower curtain. Several months later there's still no mildew, he reported.
Another problem the team faced was that the antimicrobial compound was only effective in a neutral or low pH environment, which limited its applications. If mixed with alkaline, or high Ph, solutions like detergents or bleach, the agent immediately formed a polymer. "We wanted a stable water solution that could also be used with any other alkaline solution," said Allred.
To further refine their invention, the team brought Nickel into the project. He identified several different additives that can stabilize the antimicrobial agent in alkaline environments so that even in extremely high pH solutions there was no polymer formation.
That meant the solution could be added to a load of laundry along with soap and other compounds. The treated laundry would then be bacteria-resistant-and would stay that way for months, despite repeated washings without the antibacterial agent.
Allred has tested the agent's effectiveness on commercial cotton fabric samples. After 20 cycles in a standard washing machine, the fabric was sent to a local laboratory for testing. The agent, he said, "kills 99.9 percent of bacteria but stays on the fabric."
The research group has filed two patents with Emory's Patent & License Office for their discovery and its applications. "All we need now is an appropriate business partner to handle the manufacturing, development, marketing, packaging, etc.," said Liebeskind.
Their product has potential, they say, in treating virtually any surface-hospital sheets and mattresses, bathroom tiles and curtains, carpets, paints, air ventilation systems (to wipe out airborne bacteria, like those that cause Legionnaire's disease), even toothbrushes and dirty socks, said Liebeskind. The next step, he said, is to develop a powder form, which would be even easier to handle and ship.
Colleagues have described their discovery as "simple but very elegant chemistry," Liebeskind said, adding, "We think it has real promise."
-Jeanie Lerche Davis
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