Going for gold

Plastic storage containers could soon be manufactured with built-in anti-microbial properties, following the creation of low-cost, polymer-compatible gold and silver nanoparticles.

Plastic storage containers and food packaging could soon be manufactured with built-in anti-microbial properties, following the creation of low-cost, polymer-compatible gold and silver nanoparticles.

This would prolong the shelf life of goods in shops and the home, and the nanoparticles could also enable the large-scale manufacture of odour-free shoes, socks, and clothing, as well as microbe-resistant cosmetics, which are currently prone to transmitting infections if used by more than one person.

The development by US company NanoHorizons of Pennsylvania represents the first commercially available noble metal nanoparticles engineered for use in plastic or nylon-based products.

The company claims its nanoparticles are 90 per cent cheaper than its competitors, and can also be provided in organic solvents, making them easily integrated within current manufacturing processes.

Manufacturers in the clothing and cosmetics industries have already made approaches to NanoHorizons, and according to operations director Dr. Daniel Hayes it has recently started working with a medical firm to develop implanted devices with anti-microbial properties.

‘First, we are looking at medical applications. However, these will not be first to market owing to the time it takes to get regulatory approval,’ he said.

‘We are not revealing full details of the process, but it uses colloidal chemistry. Self-assembling monolayers form a single molecular layer on the surface of a material.’

Nanoparticles of both gold and silver are already incorporated into some materials because of their antibacterial properties, but the manufacturing process is far from simple.

At present, they can be incorporated into products by mixing a bulk form of the material into a polymer or evaporating a layer of metal on to a surface. The latter method adds weight and cost and can change the material’s durability or other characteristics.

NanoHorizon’s nanoparticles, shaped like spheres or rods, are designed with specific surface chemistries and are supplied in water, methanol or ethanol, making them compatible with polymerprocessing.

They are designed to greatly increase the available surface area of the metal that can be used in a microbe-killing chemical reaction and allow less metal to be used – making the process much cheaper.

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