| TECHNOLOGY |
The researchers activated the materials' carbohydrate surface groups by tosylation and then displaced the tosylate groups by reaction with an amine reagent--a 1,4-diazabicyclo[2.2.2]octane (DABCO) group with an attached lipophilic alkyl chain. The inspiration for the reagent was a set of 1993 studies--carried out by associate professor of polymer chemistry Akihiko Kanazawa and professors of polymer chemistry Tomiki Ikeda and Takeshi Endo of Tokyo Institute of Technology, Yokohama, Japan--in which phosphonium and ammonium polymers were found to exhibit antibacterial activity.
After derivatizing the surfaces of the five carbohydrate-based materials with the DABCO-alkyl reagents, authors exposed the materials to three types of gram-positive bacteria (including staph) and four types of gram-negative bacteria (including Escherichia coli). Treatments with reagents containing 10-, 12-, and 18-carbon alkyl groups were active against gram-positive bacteria but not against the gram-negative strains.
The agent containing a 16-carbon lipophilic chain, however, was effective against both gram-positive and gram-negative bacteria. A number of gram-negative bacteria are found in the gastrointestinal tract and are responsible for diseases such as sepsis, so it's particularly important that a proposed antibacterial surface treatment not leave them out. The DABCO-hexadecane treatment kills a wide range of bacteria on simple contact. It is useful both for clothing and wound dressings, it doesn't require additional agents, and it is not removed from surfaces on washing. "The agent is chemically bonded to the surface such that it cannot be washed out under normal conditions and is not modified upon interaction with the bacteria." "Thereby, it remains capable of continually acting against the bacteria." INDEED, SURFACES derivatized with the DABCO-hexadecane reagent prevented growth of all seven bacterial strains tested, even after repeated washing and reapplication of bacteria to the surfaces. agent also kills yeast. Authors have since extended the applicability of the antibacterial effect from the five types of surfaces they initially tested to wool and silk. In fact, the researchers believe the approach will be applicable to any carbohydrate-based material their antibacterial reagent can react with.
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