Building nanoparticles layer by layer

Scientists at Leicester University are using helium nanodroplets to create nanoparticles that could have uses in electronics and medicine.

‘The technique gives us the ability to design nanoparticles layer by layer. These layers can be a solid, gas or liquid, so we could have a liquid or gaseous core with a solid shell round it,’ said Dr Andrew Ellis, who is working on the research.

The droplets of ultra-cold, superfluid liquid helium consist of a large amount of helium atoms that are loosely bound together. Atoms and molecules can enter these droplets and be assembled into structures that are not possible using conventional chemical synthesis methods.

The researchers have considered using the helium droplets to create gold nanoparticles for use as catalytic converters to clean carbon monoxide from car exhausts. The efficiency of the catalyst is dependant on the size of the gold nanoparticles, and with the new technique researchers can not only control the size of the nanoparticles but also improve the scrubbing efficiency by coating the gold onto a ‘core’ built from a different material.

Another possible use for the helium technique is to trap a drug molecule in a water-filled shell and wrap it in a thin protective layer. The molecule could then be injected into a specific area in the body and the drug released at a chosen point, for example, by illuminating the molecule with enough light to disrupt the protective shell.

‘We are still exploring what uses this might have. We hope that it will enable us to design new types of catalysts for improved manufacture of chemicals. Other possibilities include the construction of nanoparticles for storing information in smaller hard disk drives in PCs,’ said Ellis.