DNA damaging dots

Mark Green from King’s College London, UK, and Emily Howman from Oxford University, UK, are looking into the possible DNA-damaging effects of commercially available cadmium selenide semiconductor QDs capped with a zinc sulphide shell.

The preliminary studies show that both in the dark and when exposed to UV light, DNA is damaged when incubated with the QDs. The damage seems to be caused by sulfur-containing free radicals that are released when the shell is oxidised.

Green is aware that his work could have serious consequences if not treated sensibly, saying that ’this is not a scare paper. What we don’t want is another GM "Frankenstein food" situation’. He is full of praise for QDs in medical applications, in spite of his latest findings: ’If you’re looking at [biological samples] in silico, QDs are superb.’

David Schiffrin, a nanoparticles expert from Liverpool University, UK, remains to be convinced that Green’s claims about QDs causing DNA damage are accurate. ’Although these are interesting observations, I feel that one should be very cautious in reading too much into these experiments,’ he said. ’It would be important, before jumping to conclusions on the general dangers of QDs to DNA, to have a proper characterisation of the chemistry involved.’

Green comments that this study is preliminary and he is conducting more experiments to back up his theories. ’I think there are some very simple ways to overcome this,’ he says. ’I think semiconductor QDs are the future of bioimaging. Better we know the side effects now and act on them, rather than addressing them in the future.’

This contentious issue looks set to run and run, with Schiffrin saying, ’unfortunately there is a great deal of hype regarding "nanotechnology" and its dangers. An article highlighting DNA damage.can be easily misrepresented and can be, in my view, extremely misleading.’

Katharine Sanderson