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Rights: The University of Waikato
Published 30 May 2008
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Prof Richard Haverkamp, of Massey University, explains how gold nanoparticles made in plants might stay small, compared to the clumping that happens when nanoparticles are made in solution.

Transcript

DR RICHARD HAVERKAMP
One of the advantages of the technique we are proposing is that we might be able to stop these nanoparticles of gold we’ve made from clumping together and ceasing to be nano.

So if you’re precipitating the gold particles from solution then you've got to filter them out or separate them out somehow and they form a big mass of gold particles. And the reactivity is on the surface of the particles. So if the surfaces are all packed together in a mass then the surfaces aren't accessible to the chemicals, so we might as well not made all that extra surface area. So the trick to using as little gold as possible is to make sure that each gold nano particle is nicely separated and it can react with the chemicals that we want to react it with. So the idea was if plants are making these little gold nanoparticles inside their cells, all through the plants, they should be well dispersed in the plants.

So our process of making them also creates some in a dispersed form where they shouldn't clump together. And then they've got bits of carbon from the plant holding them apart, and the idea was that with our plant based method, we would make nice dispersed nanoparticles that avoided clumping.

Acknowledgements:
Stem images of nanoparticles with kind permission of Dr Richard Haverkamp and Springer Science and Business Media (published in Journal of Nanoparticle Research (2007), 9:697-700, Pick your carats: nanoparticles of gold-silver-copper alloy produced in vivo by R.G Haverkamp, A.T Marshall and D. van Agterveld.)