Silver Coating Prevents Infection in Medical Devices

Scientists have recently developed silver coatings for implantable medical devices to protect against infection, but with limited success. In a study published in ACS Central Science, a team addressed a new, long-acting silver ion-releasing coating that prevented bacteria from adhering to implants in mice and subsequently killed them. In some cases, medical care requires surgeons to implant a device such as a tube to drain a wound or bladder, or to deliver drugs directly into the blood. However, bacteria can adhere to the surfaces of these devices and accumulate on them, creating a risk for dangerous infections. Researchers are working to develop non-fouling coatings, including those containing silver, which is known to kill microbes. However, these efforts have faced numerous challenges: silver can also be toxic to human cells, and it is difficult to, for example, create a coating that continuously releases small amounts of metal over long periods. Dirk Lange and Jayachandran Kizhakkedathu wanted to identify a formulation that could overcome these and other challenges. To develop an easy-to-use coating, the team screened many sets of components that could be applied to a surface in a single step. The formula that produced the best results contained silver nitrate, dopamine, and two hydrophilic polymers. This silver-based film-forming antibacterial engineered surface ("SAFE") coating produced stable, silver-containing devices that gradually released silver ions in laboratory tests. When exposed for 28 days to eight of the most common types of bacteria causing serious infections, this new coating formula effectively kept microbes at bay. It did this by both removing bacteria from the surface and killing them with silver ions. To test SAFE's effectiveness in a living animal, the team coated a titanium implant with it and then implanted the implant under the skin of rats. One week later, researchers found significantly fewer bacteria on coated implants compared to uncoated ones. Additionally, no signs of toxicity were observed in the rats' tissues. The coating also appeared durable, showing minimal wear and tear after ovule and sterilization using harsh conditions. Researchers say that the combination of these properties could make the coating useful in many types of medical devices and implants for long-term bacterial infection prevention. Academic Reference: Durable Surfaces from Filmforming Silver Assemblies for Long-term Zero Bacterial Adhesion without Toxicity, ACS Central Science (2022). DOI: 10.1021/ acscentsci.1c01556 Source