Nanotech cleans up

The proteins which carry iron around the bloodstream are being used to make nanoparticles that could help clean up heavy metal residues from lakes, rivers and groundwaters.

Researchers from Temple University in Philadelphia are using ferritin, a protein capable of storing and releasing iron, as a template to form metal and metal oxide particles which can reduce heavy metal pollutants such as chromium into insoluble forms.

Research director Daniel Strongin and colleagues are using ferritin derived from horses to form their nanoparticles. The protein forms spheres which can hold a varying amount of iron, which in turn creates different sizes of nanoparticles.

They then alter the oxidation state of the metal to give the particles the properties needed to tackle different pollutants. 'In one case, we've been looking at the reduction of toxic chromium-6, one that the Environmental Protection Agency has on their toxic metal list for groundwater.'

Chromium-6 can be changed into insoluble chromium-3 by photocatalytic nanoparticles, says Strongin, and can then be filtered out of the water supply.

Another metal on the target list is technetium-7, which is a major problem at a nuclear waste site in Washington state.

'These large canisters of nuclear waste have been sitting there since the 1940s and 1950s and they are slowly leaking,' says Strongin.

'But we believe that this method of using nanoparticles could play a role in preventing the spread in groundwater and help facilitate cleaning it up.'