Yun and Humar used three different methods to create their intracellular “micro-lasers”.
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Living biological cells can now be turned into tiny lasers that emit light that can be used to track the spread of diseases, such as cancer. “Another challenging step will be figuring out how to use biologically generated energy from mechanical movement or a biochemical reaction to pump a cellular laser in a living body”. In theory, using different combinations of beads and dyes with different spectral properties should make it possible to individually tag nearly as many cells as exist in the human body. In one example, they injected tiny oil droplets, later filled with fluorescent dye, into human cells; when a light pulse hit the droplet, the dye atoms emitted light in a tightly focused beam.
Massachusetts General Hospital (MGH) investigators have induced structures incorporated within individual cells to produce laser light.
Handily, pig cells contain “nearly perfectly spherical” fat balls, which are conducive to lasing by resonance when supplied with a suitable light source. When an external pulse of light was directed at the droplet, the cells emitted light in a narrow beam. When the fluorescent molecules are excited, a sphere rings with light of specific wavelengths, just as an organ pipe rings with sound at a fundamental frequency and its overtones.
“The fluorescent dyes now used for research and for medical diagnosis are limited because they emit a very broad spectrum of light”, explains Seok Hyun Yun, PhD, of the Wellman Center for Photomedicine at MGH, corresponding author of the report. And biologists could learn to tag each cell with a unique laser signature, which would allow them to track thousands of cells at once. “Imagine rather than a biopsy for a lump that doctors suspect to be cancer, cell lasers helping determine what it’s made of”.
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The Harvard team isn’t alone in its research on turning cells into lasers. The new techniques turn cells themselves into tiny lasers and could make it much easier to tell tagged cells apart, since lasers have a far narrower range of wavelengths.
