A research team from the University of British Columbia (UBC) (Vancouver, British Columbia) and the Vancouver Coastal Health Research Institute (VCHRI) have developed a silver-based coating that can easily be applied to devices such as catheters and stents. This “silver bullet” has been found to kill bacteria and keep them from infecting patients with implanted medical devices.
Discovered by screening dozens of chemical components, the novel formulation of the combined UBC/ VCHRI team overcomes the complications of silver that have challenged scientists for years. The results of their study was recently published in ACS Central Science.
“This is a highly effective coating that won’t harm human tissues and could potentially eliminate implant-associate infections,” says Dr. Jayachandran Kizhakkedathu, professor in UBC’s department of pathology and laboratory medicine, Centre for Blood Research and Life Sciences Institute, and co-senior author of the study. “It could be very cost-effective and could also be applicable to many different products.”
While implanted medical devices can save lives, they carry a great risk of infection that arises from contamination as the device is being implanted. Silver has long been viewed as a potential solution because of its ability to kill bacteria, but its use on implanted devices poses several challenges, particularly its toxicity. In addition, coatings incorporating silver have proven to be complicated to make, lacked durability, and a host of other problems.
The UBC team led by Dr. Hossein Yazdani-Ahmadabadi, a former chemistry PhD student from the Kizhakkedathu laboratory, combine silver nitrate, dopamine, and two hydrophilic polymers to generate the coating. Once implanted, it releases silver ions gradually in small, controlled qualities—enough to kill bacteria but not harm human cells. It repels live and dead bacteria and other fouling agents from its surface, keeping it clean, and maintains its killing activity for longer than has been achieved by other coatings.
The researchers tested it for 30 days in an environment with a high concentration of diverse and resilient bacteria known to cause infections. Their device came away with no bacteria attached. In a seven-day test with live rats, it performed the same way and did not harm the rats’ tissues.
“Other silver-based coatings rely on contact killing, meaning the bacteria have to attach to the material in order to be exposed to the silver and die. This results in dead bacteria building up on the surface over time and rendering the device ineffective,” explains the study’s other co-senior author Dr. Dirk Lange, associate professor in UBC’s department of urologic sciences and director of basic science research at the Stone Centre at Vancouver General Hospital.
“We’re preventing that by keeping bacteria off the surface in the first place, and then killing them with the release of silver. Since we prevent attachment of both live and dead bacteria, this coating has significant potential to maintain a clean surface for any device or material for an extended period of time, which is something we haven’t seen so far,” adds Lange.
The research team looks forward to seeing how the coating performs in clinical trials, and is optimistic that their discovery could be in wide use to prevent infections in patients within the next decade.
Source: University of British Columbia, www.news.ubc.ca.