Harvard researchers have made pig-skin lasers. The technology, outlined in a paper published in Nature Photonics, showed that pumping light into fat cells could turn them into tiny, self-contained lasers.
Researchers have turned individual cells into miniature lasers by injecting them with droplets of oil or fat mixed with a fluorescent dye that can be activated by short pulses of light.
The system was devised by Seok Hyun Yun and Matjaž Humar, both optical physicists at Harvard Medical School in Cambridge, Massachusetts, and uses droplets of fat or oil within a cell to reflect and amplify light, generating a laser.
In the paper, researchers said, “On pumping with nanojoule light pulses, green laser emission is generated inside the cells. The characteristics of the lasing spectrum provide each cell with a barcode-type label which enables uniquely identifying and tracking individual migrating cells. Self-sustained lasing from cells paves the way to new forms of cell tracking, intracellular sensing, and adaptive imaging.”
The team at Harvard University turning cells into lasers has tried it before. But last time they had to put the cells inside a special optical cavity to make them shine. Pumping light into a sphere can create the resonance that produces sharply defined laser light.
This time the team showed that some cells could 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.
Seok Hyun Yun, 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.
It’s not just pig fat lasers, by the way. 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 estimated they should be able to create roughly as many unique laser tags as there are cells in the human body.
Yun cautions that the technique is not yet ready for therapeutic use. But eventually the modified cells could be used to locate target tissue, such as a cancerous tumour, and active pre-loaded, light-sensitive drugs only in that area.
