The antibacterial activity of various electroplated coatings (cobalt, zinc, copper, and cobalt-containing alloys of nickel, zinc, chromium) was determined by a 'Drop-method' antibacterial experiment against pathogenic bacteria (gram-positive bacterial S. aureus, MRSA, and gram-negative bacteria E. coli, P aeruginosa). It was found that all of them possessed a higher antibacterial activity than stainless steel. The ralationship between the inhibitory capability for the growth of bacteria and the rest potential of the electroplated coatings was also investigated. A significant antibacterial activity of the coatings was apparently displayed by a rest-potential shift to more negative values. It was suggested that all of the tested bacteria fell closely within the lethal range when the rest potentials were lower than -543 mV. However, some amount of metal ions dissolved from various from various electroplated coatings was measured; accordingly, the inhibitory capability of the simulated dissolution concentrations of metal ions the growth of bacteria is discussed.
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