‘Iron Man’ plants are supercharged by nanotech power

‘Iron Man’ plants are supercharged by nanotech power

CALLISTA IMAGES/SUPERSTOCK For daily news stories, visit newscientist.com/news Plants join the nanotech fan club Catherine Brahic BIONIC plants are...

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CALLISTA IMAGES/SUPERSTOCK

For daily news stories, visit newscientist.com/news

Plants join the nanotech fan club Catherine Brahic

BIONIC plants are here. A team of biologists and engineers has made enhanced greens with a simple injection of nanotechnology. Michael Strano of the Massachusetts Institute of Technology and his colleagues persuaded nanotubes to burrow deep into plant cells, reaching the tiny chloroplasts that photosynthesise to produce energy. The nanomaterials allow the chloroplasts to function for longer outside the plant, and may even boost photosynthesis. “The vision is to use plants as a platform for technology,” says Strano. He envisions using them as chemical sensors, and making phones or even buildings that can repair and power themselves. The results have been met with scepticism as well as delight. Critics say it isn’t clear that the nanotech has enhanced photosynthesis, and the underlying mechanisms are still obscure. Chloroplasts are tiny sacs inside plant cells that harness energy from sunlight to make sugar out of carbon dioxide and water. If extracted from the cells, they

Environment linked to autism rise once again HOW much can environmental factors explain the apparent rise in autism spectrum disorders? Roughly 1 per cent of children in the US population is affected by autism spectrum disorder (ASD). Rates in many countries, including the US, have risen sharply in recent years but no one is sure why. It is still not clear whether this is prompted by

only photosynthesise for about 4 hours before reactive chemicals called free radicals degrade them. Strano and his colleague Juan Pablo Giraldo combined a compound called nanoceria – which mops up free radicals – with carbon nanotubes. These can be pushed into leaves, but nobody had ever been able to insert them into chloroplasts. Giraldo found that coating the nanotubes with a charged substance did the trick, both in thale cress plants and in chloroplasts taken from spinach. The nanotubes extended the isolated chloroplasts’ shelf life by about 2 hours. Also, they increased the current of electrons within the chloroplasts, suggesting that they were boosting photosynthesis (Nature Materials, doi.org/rxc). Strano says this may be because the augmented chloroplasts absorb more energy from light. “This is awesome,” says Andrew Adamatzky of the University of the West of England in Bristol, UK. He says it could allow us to make nano-circuits inside living cells. “Nanotechnology can be coupled with synthetic biology to modify and enhance the function

something in the environment, a result of people having children later, or increased awareness of the condition and changes in diagnoses. In the largest study of its kind, Andrey Rzhetsky and colleagues at the University of Chicago analysed health insurance claims in the US covering over 100 million patient records – a third of the population. They used rates of genital malformations in newborn boys as a proxy for parents’ exposure to environmental risk factors. This is based on research linking a proportion of these birth defects to toxins in the

–I could do with a nano-boost–

of living organisms,” says James Collins of Boston University. Others were more sceptical. “There are a lot of big statements in this paper but only a fraction are scientifically justified,” says Marek Urban of Clemson University in South Carolina. Strano concedes that more evidence is needed to show that photosynthesis has been enhanced. Instead of boosted

electron flow, increased sugar production would be better. He also doesn’t know precisely how the nanotubes are affecting the chloroplasts’ innards. His group is working on using the chloroplasts in fuel cells, and on creating nanotube-enhanced plants to warn us of chemicals like pollutants. They have already made thale cress plants that glow if exposed to nitric oxide. ■

environment, including pesticides, lead and medicines. The team compared the rates of these defects to rates of ASD county by county. After adjusting for gender, income, ethnicity and socio-economic status, they found that a 1 per cent increase in birth defects was associated with an average increase of 283 per cent in cases of ASD. Rates of autism were several times

greater in some counties than others, which the researchers suggest is due to environmental toxins (PLoS Computational Biology, doi.org/rxd). But Dorothy Bishop at the University of Oxford points out that genetic factors can also affect rates of malformation. David Skuse at University College London says geographical variation will also be affected by the counties’ differing healthcare provision and relevant expertise. What’s more, he adds, using insurance claims data means the sample isn’t random: “There are all sorts of potential biases.” Simon Makin ■

“It isn’t clear whether increased rates of autism are down to environmental factors or something else”

22 March 2014 | NewScientist | 11