Oligodynamic effect
Encyclopedia
The oligodynamic effect was discovered in 1893 by the Swiss Karl Wilhelm von Nägeli
as a toxic effect of metal ions on living cell
s, algae
, mold
s, spores, fungi
, virus
es, 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.
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 sulfide
s. 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. Viruses in general are not very sensitive to this effect.
, 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 sanitizer
s for swimming pool
s and spas.
Many infections can be spread by doorknobs. Brass
doorknobs disinfect themselves in about eight hours, while stainless steel and aluminium knobs never do. Unvarnished brass doorknobs therefore tend to be more sanitary than stainless or aluminium doorknobs. The effect is important in hospitals, and useful in any building.
Silver is capable of rendering stored drinking water potable for several months. For this reason, water tanks on ships and airplanes are often "silvered". Metallic silver, including colloidal silver
, and silver compounds (silver sulfadiazine) are used externally in wound and burn treatments. Silver nanoparticles, obtained by irradiating a silver nitrate solution with an electron beam, are effective bactericides, destroying gram-negative
species immune to conventional antibacterial agents. Silver-coated medical implants are devices have been shown to be more resistant to biofilm formation
Silver nitrate
has been shown to be effective in inhibiting the development of the herpes simplex type 1 virus though it is largely ineffective against type 2.
Karl Wilhelm von Nägeli
Karl Wilhelm von Nägeli was a Swiss botanist. He studied cell division and pollination, but became known as the man who discouraged Gregor Mendel from further work on genetics.-Birth and education:...
as a toxic effect of metal ions on living cell
Cell (biology)
The cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos....
s, algae
Algae
Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms, such as the giant kelps that grow to 65 meters in length. They are photosynthetic like plants, and "simple" because their tissues are not organized into the many...
, mold
Mold
Molds are fungi that grow in the form of multicellular filaments called hyphae. Molds are not considered to be microbes but microscopic fungi that grow as single cells called yeasts...
s, spores, fungi
Fungus
A fungus is a member of a large group of eukaryotic organisms that includes microorganisms such as yeasts and molds , as well as the more familiar mushrooms. These organisms are classified as a kingdom, Fungi, which is separate from plants, animals, and bacteria...
, virus
Virus
A virus is a small infectious agent that can replicate only inside the living cells of organisms. Viruses infect all types of organisms, from animals and plants to bacteria and archaea...
es, prokaryotic
Prokaryote
The prokaryotes are a group of organisms that lack a cell nucleus , or any other membrane-bound organelles. The organisms that have a cell nucleus are called eukaryotes. Most prokaryotes are unicellular, but a few such as myxobacteria have multicellular stages in their life cycles...
and eukaryotic
Eukaryote
A eukaryote is an organism whose cells contain complex structures enclosed within membranes. Eukaryotes may more formally be referred to as the taxon Eukarya or Eukaryota. The defining membrane-bound structure that sets eukaryotic cells apart from prokaryotic cells is the nucleus, or nuclear...
microorganisms, even in relatively low concentrations. This antimicrobial
Antimicrobial
An anti-microbial is a substance that kills or inhibits the growth of microorganisms such as bacteria, fungi, or protozoans. Antimicrobial drugs either kill microbes or prevent the growth of microbes...
effect is shown by ions of mercury
Mercury (element)
Mercury is a chemical element with the symbol Hg and atomic number 80. It is also known as quicksilver or hydrargyrum...
, silver
Silver
Silver is a metallic chemical element with the chemical symbol Ag and atomic number 47. A soft, white, lustrous transition metal, it has the highest electrical conductivity of any element and the highest thermal conductivity of any metal...
, copper
Copper
Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...
, iron
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...
, lead
Lead
Lead is a main-group element in the carbon group with the symbol Pb and atomic number 82. Lead is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed...
, zinc
Zinc
Zinc , or spelter , is a metallic chemical element; it has the symbol Zn and atomic number 30. It is the first element in group 12 of the periodic table. Zinc is, in some respects, chemically similar to magnesium, because its ion is of similar size and its only common oxidation state is +2...
, bismuth
Bismuth
Bismuth is a chemical element with symbol Bi and atomic number 83. Bismuth, a trivalent poor metal, chemically resembles arsenic and antimony. Elemental bismuth may occur naturally uncombined, although its sulfide and oxide form important commercial ores. The free element is 86% as dense as lead...
, gold
Gold
Gold is a chemical element with the symbol Au and an atomic number of 79. Gold is a dense, soft, shiny, malleable and ductile metal. Pure gold has a bright yellow color and luster traditionally considered attractive, which it maintains without oxidizing in air or water. Chemically, gold is a...
, aluminium
Aluminium
Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....
, and other metals.
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 denatureDenaturation (biochemistry)
Denaturation is a process in which proteins or nucleic acids lose their tertiary structure and secondary structure by application of some external stress or compound, such as a strong acid or base, a concentrated inorganic salt, an organic solvent , or heat...
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
Thiol
In organic chemistry, a thiol is an organosulfur compound that contains a carbon-bonded sulfhydryl group...
groups to form silver sulfide
Sulfide
A sulfide is an anion of sulfur in its lowest oxidation state of 2-. Sulfide is also a slightly archaic term for thioethers, a common type of organosulfur compound that are well known for their bad odors.- Properties :...
s. Silver also reacts with the amino-, carboxyl-, phosphate
Phosphate
A phosphate, an inorganic chemical, is a salt of phosphoric acid. In organic chemistry, a phosphate, or organophosphate, is an ester of phosphoric acid. Organic phosphates are important in biochemistry and biogeochemistry or ecology. Inorganic phosphates are mined to obtain phosphorus for use in...
-, and imidazole
Imidazole
Imidazole is an organic compound with the formula C3H4N2. This aromatic heterocyclic is a diazole and is classified as an alkaloid. Imidazole refers to the parent compound, whereas imidazoles are a class of heterocycles with similar ring structure, but varying substituents...
-groups and diminish the activities of lactate dehydrogenase
Lactate dehydrogenase
Lactate dehydrogenase is an enzyme present in a wide variety of organisms, including plants and animals.Lactate dehydrogenases exist in four distinct enzyme classes. Two of them are cytochrome c-dependent enzymes, each acting on either D-lactate or L-lactate...
and glutathione peroxidase
Glutathione peroxidase
Glutathione peroxidase is the general name of an enzyme family with peroxidase activity whose main biological role is to protect the organism from oxidative damage...
. Bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
are in general affected by the oligodynamic effect. Viruses in general are not very sensitive to this effect.
Applications
Certain metals, such as silverSilver
Silver is a metallic chemical element with the chemical symbol Ag and atomic number 47. A soft, white, lustrous transition metal, it has the highest electrical conductivity of any element and the highest thermal conductivity of any metal...
, copper
Copper
Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...
and copper alloys, are known to be far more poisonous to bacteria than others, such as stainless steel
Stainless steel
In metallurgy, stainless steel, also known as inox steel or inox from French "inoxydable", is defined as a steel alloy with a minimum of 10.5 or 11% chromium content by mass....
and aluminium
Aluminium
Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....
, which is why they are used in mineral sanitizer
Mineral sanitizer
Mineral sanitizers for the swimming pool and spa use minerals, metals, or elements derived from the natural environment to produce water quality benefits that would otherwise be produced by harsh or synthetic chemicals....
s for swimming pool
Swimming pool
A swimming pool, swimming bath, wading pool, or simply a pool, is a container filled with water intended for swimming or water-based recreation. There are many standard sizes; the largest is the Olympic-size swimming pool...
s and spas.
Many infections can be spread by doorknobs. Brass
Brass
Brass is an alloy of copper and zinc; the proportions of zinc and copper can be varied to create a range of brasses with varying properties.In comparison, bronze is principally an alloy of copper and tin...
doorknobs disinfect themselves in about eight hours, while stainless steel and aluminium knobs never do. Unvarnished brass doorknobs therefore tend to be more sanitary than stainless or aluminium doorknobs. The effect is important in hospitals, and useful in any building.
Silver is capable of rendering stored drinking water potable for several months. For this reason, water tanks on ships and airplanes are often "silvered". Metallic silver, including colloidal silver
Colloidal silver
The medical uses of silver include its incorporation into wound dressings to treat external infections, and its use as an antiseptic and disinfectant in medical appliances...
, and silver compounds (silver sulfadiazine) are used externally in wound and burn treatments. Silver nanoparticles, obtained by irradiating a silver nitrate solution with an electron beam, are effective bactericides, destroying gram-negative
Gram-negative
Gram-negative bacteria are bacteria that do not retain crystal violet dye in the Gram staining protocol. In a Gram stain test, a counterstain is added after the crystal violet, coloring all Gram-negative bacteria with a red or pink color...
species immune to conventional antibacterial agents. Silver-coated medical implants are devices have been shown to be more resistant to biofilm formation
Chemistry of biofilm prevention
Biofilm formation occurs when free floating microorganisms attach themselves to a surface. They secrete extracellular polymers that provide a structural matrix and facilitate adhesion. Because biofilms protect the bacteria, they are often more resistant to traditional antimicrobial treatments,...
Silver nitrate
Silver nitrate
Silver nitrate is an inorganic compound with chemical formula . This compound is a versatile precursor to many other silver compounds, such as those used in photography. It is far less sensitive to light than the halides...
has been shown to be effective in inhibiting the development of the herpes simplex type 1 virus though it is largely ineffective against type 2.