Efficient Silver Release From Ion Exchange Silver Dressings in Biologically Relevant Media

Silver-containing wound dressings commonly are used when there is a risk of infection. These commercial antimicrobial silver dressings have various compositions that use different substrates and/or silver sources. Common silver sources are ionic silver (Ag+) and metallic silver (Ag0). A third source of silver is ion exchange silver compounds (Ag+ complex), in which silver ions are encapsulated in an inorganic carrier to moderate the availability of the silver ions and are released via an ion exchange mechanism.

In this study, silver release of different types of silver dressings (Ag+, Ag0, Ag+ complex) in biologically relevant media is investigated.

Simulated wound fluid (SWF) and SWF in combination with 5% bovine serum albumin were used as the extraction media.

The composition of the extraction media was found to strongly affect the release of silver. The silver released from most silver dressings peaked at ca 0.5 ppm of soluble silver without any protein in the extraction media. Apparent equilibria established between silver and the salts used for SWF were disrupted by the presence of the protein. This resulted in a dramatic increase in silver release over ionic solutions in the absence of the protein. Dressings differed dramatically in their silver release efficiency. The nature of the silver played a more significant role than the silver content in the dressings.

The ion exchange (Ag+ complex) silver dressing was shown to be the most efficient among all the dressings tested for silver release.