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Silver v. Zinc Antimicrobials

zinc antimicrobials, MicroBlok Z, MicroBlok, Plastics Color Corporation

Zinc antimicrobials are especially useful in areas subject to high humidity.

When it comes to antimicrobial additives for plastics, there is more than one choice. While silver tends to be more versatile and efficacious than alternatives such as zinc, zinc oxide is making its mark in the antimicrobial arena.

Both silver and zinc oxide (ZnO) are well known for their antimicrobial and healing properties, yet silver remains the most widely used additive for killing bacteria particularly on medical device surfaces. However, studies done in recent years have shown that ZnO nanoparticles added in various concentrations in tests involving e.Coli and other bacteria have proven to be an effective antimicrobial agent.

As reported in Medical Product Manufacturing News (March 2011, Vol. 27 #2) by Bob Michaels, “. . . despite [silver’s] prevalence, this noble metal is incompatible with some materials – such as acetal – that are commonly used to manufacture medical devices.” Hence the interest in “developing alternatives to silver-based antimicrobial agents that can be incorporated into acetal. One such candidate is zinc.”

Testing done by a group of scientists at the Department of Biotechnology, CITM College, Faridabad, Haryana, India, led by Sarvesh Rustagi, on ZnO as an alternative to silver, revealed that as the ZnO concentrations were increased, the greater the effect on inhibiting growth rates of bacteria such as e.Coli and Enterobacter, among others. The conclusion by this group was that ZnO nanoparticles “could be potentially considered as an effective antimicrobial agent.”

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