Ionic silver vs nano silver: Which is more effective at killing bacteria on surfaces?

Silver is recognised as an invaluable tool in the fight against infectious diseases. However, its use is certainly far from a modern invention. The ancient Greeks and Romans used silver as a medicinal remedy for centuries by applying silver ointments to wounds and using silver-coated dressings to prevent infection.

In more recent times, silver threads have been used as a component in burn bandages for decades. The properties of silver help prevent infection and inhibit the growth of bacteria and other microorganisms.

Silver can also be incorporated into materials such as plastics, textiles, wall cladding, flooring or paints to make them antimicrobial. The silver works to actively inhibit the growth and reproduction of microorganisms like bacteria, viruses, and fungi on surfaces. Utilising antimicrobial materials in hygiene critical areas throughout hospitals, medical practices, schools, commercial kitchens and laboratories is common practice these days. 

However, not all forms of silver have equally effective results. Ionic silver and nano silver are two different forms of silver commonly used in antimicrobial formulations. But it’s important to be aware that they differ in their physical properties and efficacy.

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What's the difference between ionic silver and nano silver?

Ionic silver refers to silver-ions which have a positive electrical charge and are highly reactive, allowing them to easily bind with negatively charged molecules, such as bacteria and viruses.

Nano silver, on the other hand, consists of microscopic silver particles (nanoparticles). These particles are larger than individual silver-ions and have a neutral electrical charge. This type of silver is often marketed as “nano silver” when incorporated into products such as dietary supplements. The use of the term "nano silver" has created an impression amongst buyers that silver nanoparticles represent cutting-edge technology and are extremely toxic to bacteria.

While ionic silver has long been understood to be a highly effective antimicrobial agent due to its reactive properties, nano silver's efficacy has been a topic for debate.

What does the research say?

In order to determine the efficacy of nano silver compared to ionic silver, researchers from Rice University conducted a series of tests back in 2012.

The researchers synthesised silver nanoparticles and exposed the particles to bacteria inside an anaerobic chamber to eliminate any chance of oxidation. It was found that the nanoparticles, even up to a concentration of 195 parts per million, were not toxic to any bacteria.

The same testing was carried out with silver-ions. It was determined that with the ionic silver, a concentration of about 15 parts per billion killed all bacteria present. This told researchers that the nanoparticles were 7,665 times less toxic than the silver-ions, indicating negligible toxicity.

The results of these tests showed once and for all that silver nanoparticles are practically benign in the presence of microbes.

So when choosing antimicrobial products, be sure the formulation contains silver-ions, not nano silver.

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Start your infection control journey with AM360

The team at AM360 is ready to help start you on the way to getting the best infection control fit-out materials on the market. All of our products utilise silver-ion technology and have been lab-tested to rapidly kill viruses and prevent the growth of bacteria, mould, and viruses.

Talk to us today and limit your infection risks by calling 1300 884 978 or by filling out the enquiry form below, and we'll get back to you.

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