Scientists in Japan have developed an ultra-thin anti-microbial lining to eliminate human body odour – commonly known as BO.
The lining, developed at the University of Tokyo, is less than 10 nanometres thick and consists of silver and tannic acid, a type of polyphenol.
Polyphenols are organic compounds found in chocolate and red wine, but are responsible for their infamous ability to stain clothing and tablecloths.
Fortunately, the researchers’ coating, called Ag/TA, is completely clear so it doesn’t discolour textiles, but best of all, it can survive being washed.
It could be used to coat newly-made textiles in a factory, or even be available in supermarkets for the public to apply to their own existing garments.
Despite their ability to neutralize pathogens, polyphenols and silver are considered to be extremely safe. Polyphenols are in many kinds of foods consumed daily, and silver does not interact with the human body. So Ag/TA coating could be done by anyone in the home, not just in tightly controlled industrial settings
In lab trials, the researchers have shown a range of textile types – including cotton, polyester and silk – can be treated with the ‘cost-effective and convenient’ lining.
Treated textiles can be washed multiple times without degrading the lining’s antimicrobial and therefore anti-odour properties.
‘What’s most exciting is not the ease of application, but how effective the coating is,’ said study author Joseph Richardson at the University of Tokyo’s Graduate School of Engineering.
‘This isn’t just a hypothetical situation limited to the lab, I’ve tried it on my own shirts, socks, shoes, even my bathmat.
‘We’d like to see what other useful compounds polyphenols might help bind to fabrics. Antimicrobial silver might just be the start.’
BO occurs due to tiny microbes such as bacteria on a person’s skin breaking down protein molecules within sweat, producing odour as a result.
Silver is already well known for its antimicrobial properties, but can be difficult to apply to things like clothes in an easy and efficient way.
So, in experiments, the researchers used tannic acid to bind silver (Ag) to fabrics.
The binding power of tannic acid is so strong that coated textiles tested by the researchers maintained antimicrobial and anti-odour properties for at least 10 washes.
Atomic force microscopy (AFM) image shows Ag/TA coating on silicon deposited in under 10 seconds
According to Richardson, there are two methods to apply our antimicrobial silver coating to textiles, suitable for different use cases.
The first method might be useful for commercial clothing or fabric producers, where textiles are simply bathed in a mixture of the silver compound and the polyphenol binder.
The second method, more suited to small-scale settings including the home, is to spray items of clothing.
An advantage of this would be that people can add the coating to their already-existing and much-loved garments.
If marketed, it could potentially be used as an alternative to deodorant to ensure people don’t get smelly.
Researchers also think the lining has use cases beyond the wardrobe, such as health care settings.
‘We wanted to study the effect of the antimicrobial coating not just on odour-causing bacteria, but also on fungi and pathogens like viruses,’ said Richardson.
A range of textile types can be treated by the researchers’ method, and items can be washed multiple times without losing the antimicrobial and therefore anti-odour property (stock image)
‘With so many variables to control, it was a challenge of time and complexity to test variations of compounds against variations of microorganisms.
‘But through carefully optimizing our testing methods, we found that the coating neutralises everything we tested it on.
‘So Ag/TA could be useful in hospitals and other ideally sterile environments.’
The full findings have been published today in the journal Scientific Reports.