I completely missed this paper when it came out at the beginning of the month, but thank goodness a recent article in New Scientist brought it to my attention, this is an incredibly study.
Normally, particles in a solution cause light to scatter. This is the basis of the optical density readings that we use to measure bacterial cultures. However, researchers at San Francisco State University discovered that when they added the cyanobacterium Synechococccus to the mix, something totally unexpected happened...
... well. It's not totally unexpected. The research group led by Zhigang Chen shone green lasers through a culture of Synechococcus and found that the light did not scatter at all, in fact, the individual cyanobacteria assembled into a "fibre" around the light which enabled the laser beam to propagate much further that it would normally.
The phenomenon has been documented before by which a difference in the refractive index of the bacteria and the culture medium causes bacterial cells to be pulled towards the centre of the light beam. This causes the cells to align precisely along the laser beam creating a biological fibre for it to travel down, instead of scattering the light.
Did someone say "organic, self assembled, broadband cables"?
I might have said that on Twitter when I first read the study but lets not get ahead of ourselves. Chen hopes that the technology could be used for producing biological microchips which may be a bit farfetched as of today. He does however suggest that other cells eg. red blood cells may exhibit the same tendencies which would be a very powerful innovation in the field of medical diagnostics.
Read the full paper here.
Nonlinear Self-Action of Light through Biological Suspensions
It is commonly thought that biological media cannot exhibit an appreciable nonlinear optical response. We demonstrate, for the first time to our knowledge, a tunable optical nonlinearity in suspensions of cyanobacteria that leads to robust propagation and strong self-action of a light beam. By deliberately altering the host environment of the marine bacteria, we show experimentally that nonlinear interaction can result in either deep penetration or enhanced scattering of light through the bacterial suspension, while the viability of the cells remains intact. A theoretical model is developed to show that a nonlocal nonlinearity mediated by optical forces (including both gradient and forward-scattering forces) acting on the bacteria explains our experimental observations.
Nonlinear Self-Action of Light through Biological Suspensions.Bezryadina, Anna and Hansson, Tobias and Gautam, Rekha and Wetzel, Benjamin and Siggins, Graham and Kalmbach, Andrew and Lamstein, Josh and Gallardo, Daniel and Carpenter, Edward J. and Ichimura, Andrew and Morandotti, Roberto and Chen, ZhigangPhys. Rev. Lett. 2017 10.1103/PhysRevLett.119.058101