Scientist of the soft stuff

<strong>Athene Donald</strong>, Physicist

When Isaac Newton looked at an apple, he saw an object that falls to earth because it is less massive than the planet. Athene Donald, professor of experimental physics at Cambridge University, sees a lump of foam in a green coat. A carrot is a sort of foam, too, because it is made of patches of fluid inside solid compartments. Donald has shown that carrots become bendy when they get old because the amount of liquid in their cells shrinks; because liquids are incompressible, each cell (that is, each compartment in the foam) becomes less stiff.

On its own, this might sound like a piece of potted science. Or it might lead to carrots that stay stiff after cooking, like water chestnuts. Either way, Donald's approach is the point. Her way of looking at the world could change it by ushering in early diagnostic instruments - and even possible treatments - for neurodegenerative diseases such as CJD and Alzheimer's (the latter a condition that experts predict could afflict up to 100 million people worldwide by the year 2050), not to mention advances in technologies as diverse as solar cells and prosthetic limbs.

Physicists tend not to hack at problems by laying out the identities of the different bits involved, as molecular biologists do. Instead, their instinct is to assume that all the bits are pretty much the same, and that messy particulars should be dealt with later, once the answer is halfway there. Donald is unusual among physicists because she is a soft-matter expert who noticed early in her career that soft-matter physics spans all living objects - not just the synthetic gels, emulsions and the like for which it is better known.

In December, after two decades of research at the interface of physics and biology (including a few early years earning the disapproval of some eminent colleagues), Donald opened Cambridge's sleek-looking physics of medicine department, of which she is director. In March, she will become the 2009 European Laureate of the Women in Science Awards, sponsored by 'Oréal and Unesco, as only the second British winner in the prize's 11-year history. She is a fellow of the Royal Society and director of WiSETI, Cambridge's initiative to get women into subjects that involve doing sums.

The recent attention on Donald stems from her less-is-more physicist's approach to detail on proteins. If biology is all about squishy and lumpy materials, medicine is often a means of manipulating the lumpiness or squishiness of them. When diabetes strikes in middle age it is sometimes caused by unwanted lumps clogging up the cells in the pancreas that make insulin. Alzheimer's is a disease of lumps in brain cells. In both cases, the lumps are made of broken or "denatured" proteins that stick together and create what are called amyloid fibres.

Donald investigates how to slow these particular proteins' rate of clumping and how to capture images of them using a technique she helped pioneer - "environmental scanning electron microscopy". However, she prefers to think of her work's focus as trying to understand and control the interactions of model molecules. For example, she has used ice cream in her microscopy experiments as a model of a foamed emulsion with a complex structure that falls apart at room temperature.

"Once you've denatured proteins, their behaviour is the same," says Donald, "whether they're in food or in an Alzheimer's patient." That is why a background in soft matter can aid the study of neuroscience. Donald is happy to be a visible role model for young women who may be put off science by its stereotypes. But with the growth in elderly populations her work could be crucial in dealing with what Alzheimer's Disease International describes as "a public health and social care emergency . . . no country is currently prepared to deal with a crisis of this magnitude".

Anna Petherick is research highlights editor at Nature magazine

Alzheimer's: the facts

Samira Shackle

Alzheimer's is a progressive, ultimately fatal, disease, in which nerve cells in parts of the brain degenerate and die

It is named after Dr Alois Alzheimer, who first reported on the condition in 1906 after spending five years documenting the case of a 51-year-old woman he called "Auguste D"

"Dementia" describes the symptoms of the disease, which include memory loss, confusion, loss of speech, incontinence and mood swings. Although there are other causes, 50-60 per cent of dementia cases are caused by Alzheimer's

An estimated 30 million people worldwide suffer from dementia. That figure is expected to rise to well over 100 million by 2050

Dementia costs the UK £539 every second. Every year, 60,000 deaths in this country are directly attributable to it

Drugs used to treat Alzheimer's can improve dementia temporarily or stabilise the onset of the disease, but cannot cure it

Sufferers have included the US president Ronald Reagan, the British prime minister Harold Wilson and the novelist Iris Murdoch, whose husband, John Bayley, wrote a tender memoir about her decline