History of Silver as medicine
The use of silver for the treatment of various conditions to prevent the transmission of infection dates back to at least 4000 b.c.e. Medical applications of silver are documented in the literature throughout the 17th and 18th centuries. The bactericidal activity of silver is well established. Silver nitrate was used topically throughout the 1800s for the treatment of burns, ulcerations, and infected wounds, and although its use declined after World War II and slowly replaced by antibiotics.
The use of topical silver to reduce bacterial burden and promote healing has been investigated in the setting of chronic wounds and ulcers, post-operative incision dressings, blood and urinary catheter designs, endotracheal tubes, orthopedic devices, vascular prostheses, and the sewing ring of prosthetic heart valves. The beneficial effects of silver in reducing or preventing infection have been seen in the topical treatment of burns and chronic wounds and in its use as a coating for many medical devices. However, silver has been unsuccessful in certain applications, such as the Silzone heart valve. In other settings, such as orthopedic hardware coatings, its benefit remains unproved.
More recently, silver technology has focused on the use of nanoparticles (nanocrystalline silver) as an antimicrobial agent. Nanocrystalline silver releases sub-crystalline particles of uncharged metallic silver containing fewer than eight atoms. These particles react less rapidly with chloride ions, allowing silver to be released from the carrier dressing for a longer period of time. Free radicals produced from silver nanocrystals may perpetuate membrane damage.
Silver nanoparticles also permeate cells, interfering with bacterial respiratory chain enzymes to inhibit energy production and growth. The bactericidal activity of silver is dependent on particle size; 10-nm particles exhibit complete interaction with the bacteria, whereas larger particles do not, suggesting that nanoparticles exert greater bactericidal effects. Although the molecular mechanisms of the action of silver against bacteria continue to be investigated, it is clear that silver nanoparticles are powerful bactericidal agents.
Alexander JW. History of the medical use of silver. Surg Infect. 2009;10:289–292.