Oligodynamic effect

The concept of Oligodynamie goes back to the Swiss botanist Carl Wilhelm von Naegeli and describes a damaging effect of metal cations ( positively electrically charged metal ions) on living cells.

Operation

The ions of certain metals exhibit (sometimes weak ) detrimental effect on various pathogenic agents, including bacteria, viruses and fungi are to be counted. The metals for which this effect could be observed so far are sorted in descending order effect:

Also, gold and osmium show this effect. In the bacteria, the Gram-positive bacteria may be slightly more sensitive than the Gram-negative bacteria. The exact mechanism of action is not fully understood, it has been found a failure of bacterial metabolism, it was reaction with cytochromes and the formation of complexes with DNA and RNA.

Furthermore, it is known that silver ions can affect the permeability of cell membranes so that they can bind to sulfur bridges of proteins and there cause a disturbing effect on enzymes ( silver can form with thiol groups of enzymes sulfides and react with amino and carboxy groups of enzymes and this thereby inactivate. ) The lactate dehydrogenase and glutathione peroxidase are, for example, inhibited in their activity. ( Shinogi, 1993) The majority of the reports on the in vitro effect of silver, after sufficient exposure time of several hours against microorganisms are positive, thus to be seen as effective. It is also described a little antiviral effect of metal ions on viruses is also to increase by increasing the ion concentration hardly.

But Critics also emphasize that the biocidal effect of silver is (especially as colloidal silver ) is not always reliable. So failed silver in colloidal form completely in a study at different concentrations against various microorganisms. ( P. van Hasselt, 2004) Hasselt literally: "As the tested colloidal silver solutions did not show any antimicrobial effect in vitro on the microorganisms, claims of colloidal silver 's antimicrobial potency are misleading and there is no place for it as to antiseptic. " ( "Because the tested colloidal silver solutions no in vitro ( rlei ) showed antimicrobial activity against microorganisms, are assertions that colloidal silver has antimicrobial abilities, misleading and therefore there is no place for it as an antiseptic. " )

There are also reports on a damaging effect on algae and plant cells. A typical feature of the oligodynamic is the relatively long contact time ( measured in hours ) required to achieve the full antimicrobial effect. Silver sensitive bacteria can become resistant over time, that is insensitive to silver ions. The highest silver concentrations, allowable silver -resistant microorganisms, were 10 g / l and this corresponds approximately to the 500 times the value for silver- sensitive bacteria.

Application

The oligo-dynamic effect is exploited in some disinfectants, usually in combination with chlorine compounds or hydrogen peroxide. Even with the preservation of drinking water in mobile water tanks ( on ships, airplanes, camping ) you will find applications of Oligodynamie. In medicine and catheters, dressings and textiles are equipped so that they can release silver ions. Silver-containing agents are in wound treatment (mainly burns ) are used, for example, silver sulfadiazine. The low incidence of caries in the edge region of cast gold fillings (inlays ) is also attributed to the oligo-dynamic effect of dental gold alloys.