Cells (Finally) Shoot Lasers

Biological cells have become living laser sources thanks to two separate research groups led by Malte C. Gather at the University of St. Andrews in Scotland and Seok-Hyun (Andy) Yun at Harvard Medical School (Nano Lett. 2015, DOI: 10.1021/acs.nanolett.5b02491; Nat. Photonics 2015, DOI: 10.1038/nphoton.2015.129). The teams found that cells could survive ingesting microscopic particles—including polystyrene, barium titanate, and lipid droplets—that are capable of trapping incident light. By surrounding or filling these structures with dye molecules that amplify optical signals, the researchers effectively stuffed two of a laser’s three core components into cells. The final ingredient, a power source, was provided by nonlethal, nanosecond laser pulses, provoking the particles and dyes within cells to emit their own laser light. Different combinations of chemistries and particle sizes shine with different and well-defined laser spectra, giving the researchers a tool kit to tag and monitor individual cells. This innovation could expand optical medical therapies and diagnostics to an extent not seen since the advent of fluorescent tagging, the researchers say.