A team at Harvard University (Cambridge, MA) has tried turning cells into lasers before, putting the cells inside a special optical cavity to make them shine (see "Lasers Made from Human Cells") since pumping light into a sphere enables the resonance that produces sharply defined laser light. But this time the team has shown that some cells can lase on their own. They chose pig fat because each cell contains a large, nearly perfectly spherical ball of fat inside it. They added a glowing fluorescent dye and then started up the microlasers by shining in light through an optical fiber.

The technology published in Nature Photonics confirms that pumping light into fat cells turns them into tiny, self-contained biolasers. This microlaser technique could afford scientists new ways to study and use cells.

Seok Hyun Yun, the paper's senior author and an associate professor at Massachusetts General Hospital and Harvard Medical School, says his long-term goal is to use intracellular microlasers as research tools, sensors, or perhaps as part of a drug treatment. Lasing cells could add to the repertoire of techniques that scientists have to label and study cells like adding quantum dots or bioluminescent particles. For instance, the laser light put out by a sphere inside a cell will change depending on how much pressure a cell is under.

Yun's team also found they could turn others cells into a laser by injecting oil droplets into them. They also tried inserting tiny polystyrene beads to change the tuning of the laser. By combining beads of different sizes with several fluorescent dyes, the researchers said that they estimated that they should be able to create roughly as many unique laser tags as there are cells in the human body.

SOURCE: MIT Technology Review; http://www.technologyreview.com/news/539696/making-pig-fat-into-a-laser/