Researchers studying the high Alpine plant edelweiss may have stumbled on an impressive new sunscreen strategy. Brussels-based researcher Jean Pol Vigneron and his colleagues wondered how the eledweiss plant was able to withstand so effectively the high doses of UV radiation that accompany life at high altitude. To find out they measured how the plant absorbed or reflected lights of different wavelengths, expecting to see the UV being bounced back at them. But they were shocked to see that whilst most wavelengths were reflected, UV wasn't. "It's astonishing, but the plant completely absorbs the UV," says Vigneron. Edelweiss leaves are covered in fine white hairs and the team wondered whether they might be responsible for soaking up the UV. To find out they studied them under the electron microscope, which revealed that the hairs are made up of tiny fibres, each just 176 nanometres (millionths of a millimetre) across. This diameter means that the fibres are about the same size as the wavelength of ultraviolet light, and can interact with it. The researchers think that the tiny strands steer the UV away from the leaf where it could do harm and into the middle of the hair where it can be soaked up by a material in the centre, possibly purewater, which is a good absorber of UV. Vigneron suspects that the same trick could also work for sun-lovers seeking better protection than that offered by standard titanium-based creams and lotions currently on the market.
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