Living human cells have resonant frequencies 鈥� rates at which they will naturally oscillate if the conditions are right. This has been suspected for decades, but researchers have now measured what some of those frequencies are.
When an object vibrates, the rate at which it moves back and forth has a big effect. At many frequencies, the object will only vibrate a little or quickly diminish, but at its resonant frequencies the size of the vibration becomes large.
at the Spanish National Research Council and his colleagues decided to investigate what these resonant frequencies are for a single living human breast cell.
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Over many repeated experiments, the researchers used a tiny cantilever made of gold and silicon to pick up individual human breast cells from a dish. The process of picking the cells up caused them to vibrate.
Because the cantilever was so small 鈥� only 50 micrometres long and 270 nanometres thick 鈥� it vibrated in response to the cell鈥檚 own motion. By illuminating the cantilever with a laser, the researchers could then measure this subtle motion from the way the light reflected.
Tamayo says they had used a similar set-up to measure other cell characteristics before and noticed that sometimes the cantilever moved in subtle but unexpected ways. They started to suspect that those motions came from the cell on top of the cantilever vibrating at some resonant frequency during those experiments. But because cells are very different from the usual objects we think of as resonating strongly, like tuning forks, for example, the idea seemed far-fetched.
鈥淲e could never imagine that a living cell鈥� could vibrate like this,鈥� he says.
Yet, using simple mathematical equations, the team was able to estimate the resonant frequencies of a human breast cell. One was between 10 and 30 kilohertz, right where audible sound turns into ultrasound, while the other was between 150 and 180 kilohertz, outside the realm of human hearing.
at the University of Hawai驶i at M膩noa says that some theoretical models for living cells鈥� resonant frequencies were developed 20 years ago, including in his own work, but hadn鈥檛 been directly tested in the intervening years. The new measurements could be a step towards a revived interest in using vibrational properties of single cells for disease diagnosis, like detecting changes in the resonances of cells affected by illness, he says.
The experiment may also open the door for selectively destroying cells by triggering their resonant frequencies with sound waves, says at Peking University in China.
Journal reference:
PRX Life,
