Originally Published EMDM October 2005
Industry News
Silver-Based Coating Reduces Nosocomial Infections |
Based on a coating technology developed for wound dressings, SilvaGard allows manufacturers to apply antimicrobial silver to medical devices without altering their surface chemistry or dimensions. |
A firm has developed a process that enables the application of silver nanoparticles to device surfaces in a uniform, safe, and cost-effective manner. The technology can be used to prevent hospital-related infections, according to Bruce Gibbins, founder and chief technology officer of AcryMed Inc. (Portland, OR, USA).
SilvaGard technology allows manufacturers to apply antimicrobial silver to the surface of medical devices without chemically or dimensionally affecting the substrate. SilvaGard has been licensed for its first medical device application and is currently in production.
“There are 2 million hospital-acquired infections in the United States alone each year, 90,000 of which result in death,” says AcryMed president and CEO Jack McMaken. Half of those infections are associated with catheters and other percutaneous devices, he adds. SilvaGard can prevent the formation of biofilms on products of this type, says the firm.
Silver nanoparticles in solution is a recently developed technology that originated from silver antimicrobial applications for burns and wound dressings. These dressings are now used worldwide.
The technology uses either an aqueous or a solvent-based process, depending on the needs or characteristics of the medical device to be treated. During the process, the outer layer of each silver nanoparticle oxidizes upon exposure to air or body fluids. This step forms a monolayer of silver oxide (Ag2O) on the outside of each nanoparticle. The silver oxide then dissolves in the body fluid to produce the Ag+ form of antimicrobial silver that fights microorganisms. Because the vast number of nanoparticles on the medical device surface range from 5 to 15 nm in size, a large reservoir and large surface area of antimicrobial silver form on the device. The duration of activity depends on the level of treatment. Elution studies using radioactive silver have predicted that it is possible to achieve antimicrobial levels that last for more than a year, notes Gibbins.
This approach is a surface treatment rather than a coating. Unlike many surface coatings, the method does not change the dimensions of even minuscule medical devices. This solution-based approach also creates a surface comprising a conformal deposition of tightly adhering particles of silver. This deposition occurs on any surface brought in contact with the fluid vehicle. It is difficult to get silver flow to turn corners. This limitation can be overcome by silver nanoparticles in solution, which uses a fluid delivery vehicle rather than sputter coating or plasma to deliver the silver to the desired surface area. For example, it is possible to treat both the surface and the lumen of a catheter simultaneously.
It’s important to note that masking can be used on areas where treatment is not desired, adds Gibbins. This is currently beyond the capability of other commercial silver microbial technologies that are applied either by vacuum deposition or by electroplating, he says.
The antimicrobial silver nanoparticles are designed to be deposited onto the surfaces of medical devices after they are manufactured. This frees device manufacturers from having to requalify the devices’ base material, which is required when compositional changes are caused by adding something to the mix.
For more information, contact AcryMed Inc., 12232 S.W. Garden Place, Portland, OR 97223, USA; phone: +1 503 6249830; fax: +1 503 6390846; Internet: www.acrymed.com.
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