Report Touts Development of Antibacterial Polymer for Use with Implants
A team of reseachers from the University of Washington in Seattle has developed a polymer that gradually releases antibiotics, making it possible to develop implants and other medical devices that remain infection-free. It is hoped that the material might be used in devices such as catheters, pacemakers, heart valves, coated stents, or virtually any polyurethane device.
Buddy Ratner, a professor of bioengineering at the university and leader of the study, says that "commonly used devices like catheters account for about 50,000 hospital deaths in the United States a year, many of them because of infection. Once the bacteria get on the device, they are extremely difficult to remove and are very resistant to treatment." According to Ratner, "it can take 100 times the concentration of antibiotic to kill the bacteria when they are attached as it takes to kill them when they are free."
The polymer counteracts the attachment process by slowly releasing the antibiotic. Consisting of a combination of antibiotic ciprofloxacin and polyethlyene glycol mixed with the polyurethane commonly used in medical devices, the original version of the polymer released material too quickly, according to Ratner. To remedy this, the team used a plasma process to coat the material with a 1020-atom-thick layer of butyl methacrylate. Fluids pass through this layer, which dissolves the polyethylene glycol and makes the polyurethane porous. The antibiotic then leaches out of the polyurethane, with the coating controlling the rate of dispersion.
A plasma process used to coat a polymer with butyl methacrylate has enabled researchers to effectively control an antibiotic's rate of dispersion.
The researchers say that the system killed bacteria for 5 days. There is another potential advantage of the polymerthe high concentration of the antibiotic prevents the development of drug-resistant organisms, which occurs when bacteria exposed to an antibiotic survive. The researchers are also working on a similar development for silicone devices, Ratner says.David Bowen