London, Dec 22 (IANS) British researchers have developed a breakthrough technique that uses sound rather than light to see inside live cells, a finding that has potential application in stem-cell transplants and cancer diagnosis.

The new sub-optical phonon (sound) imaging technique uses shorter-than-optical wavelengths of sound and could even rival the optical super-resolution techniques. 

It provides invaluable information about the structure, mechanical properties and behaviour of individual living cells at a scale not achieved before.

"Like ultrasound on the body, ultrasound in the cells causes no damage and requires no toxic chemicals to work. Because of this, we can see inside cells that one day might be put back into the body, for instance as stem-cell transplants," said Matt Clark, Professor at the University of Nottingham in Britain.

In optical microscopy, which uses light (photons), the size of the smallest object you can see or the resolution is limited by the wavelength.

For biological specimens, the wavelength cannot go smaller than that of blue light because the energy carried on photons of light in the ultraviolet and shorter wavelengths is so high it can destroy the bonds that hold biological molecules together damaging the cells.

Also, the fluorescent dyes used in optical super-resolution imaging are often toxic and it requires huge amounts of light and time to observe and reconstruct an image which is damaging to cells.

However, sound does not have a high-energy payload. This uses smaller wavelengths and enables to see smaller things and get higher resolution images without damaging the cell biology, the researchers noted.

The study is published in the journal Scientific Reports.