The oligodynamic effect (Greek oligos = few, dynamis = force) was discovered in 1893 by the Swiss Karl Wilhelm von Nägeli as a toxic effect of metal ions on living cells, algae, molds, spores, fungus, virus, prokaryotic and eukaryotic microorganisms, even in relatively low concentrations. This antimicrobial effect is shown by ions of: mercury, silver, copper, iron, lead, zinc, bismuth, gold, aluminium and other metals.

Contents 1 Mechanism 2 Applications of the oligodynamic effect 3 References 4 External links

[edit] Mechanism

Metal ions, especially those of heavy metals, show this effect. The exact mechanism of action is still unknown. Data from silver suggest that these ions denature enzymes of the target cell or organism by binding to reactive groups, resulting in their precipitation and inactivation. Silver inactivates enzymes by reacting with the thiol groups to form silver sulfides. Silver also reacts with the amino-, carboxyl-, phosphate-, and imidazole-groups and diminish the activities of lactate dehydrogenase and glutathione peroxidase. Bacteria are in general affected by the oligodynamic effect, but they can develop a resistance to heavy metals and/or silver. Viruses in general are not very sensitive to this effect. It takes several hours or more for the exposure to heavy metals to ultimately sanitize, or kill all of the bacteria on a surface.

[edit] Applications of the oligodynamic effect

Certain metals, such as silver, copper and copper alloys, are known to be far more poisonous to bacteria than others, such as stainless steel and aluminium, which is why they are used in mineral sanitizers for swimming pools and spas.

Many infections can be spread by doorknobs. Brass doorknobs automatically disinfect themselves in about eight hours, while stainless steel and aluminium knobs never do. Brass doorknobs therefore tend to be more sanitary than stainless or aluminium doorknobs. The effect is important in hospitals, and useful in any building.^[1]

Silver is capable of rendering stored drinking water potable for several months. For this reason, water tanks on ships and airplanes are often "silvered".^[2] Metallic silver, including colloidal silver, and silver compounds are used externally in wound and burn treatments.^[3]

[edit] References

• Original article by Nägeli: v. Nägeli K.W. 1893. Über oligodynamische Erscheinungen in lebenden Zellen. Neue Denkschr. Allgemein. Schweiz. Gesellsch. Ges. Naturweiss. Bd XXXIII Abt 1.

[edit] External links

• engl. Doc about the oligodynamic effect at doorknobs