Who knew cells could be used as tiny lasers? Researchers at Harvard Medical School developed three methods to produce glowing cells. The first way involved oil droplets filled with fluorescent dye being injected into cells. This formed an optical cavity which, when stimulated with a specific wavelength of light, would excite the atoms in the dye. More specifically, the electrons were excited to a higher energy level, which is an unstable state, thus the electrons fall back down and emit a photon of light to rid themselves of the excess energy so it can return to a more stable state.
The second technique used polystyrene beads 10 micrometres long (the width of a cotton fibre) sprinkled in a petri dish containing macrophages. These white blood cells ingested the beads, and due to the mechanism described before, when a specific wavelength of light was shone onto the macrophages the cells began to emit light.
The final procedure made the most of the natural droplets of fat in our cells.
This idea of tagging cells has great potential. It could lead to new innovative ways of tracking cancer cells, or distinguishing between different types of cells. It could even play a key role in better understanding how the immune system functions, in particular how individual immune cells respond to inflammation (macrophages, eosinophils, mast cells, basophils etc). It could even be used to study the early development of organisms.
Read the full story: Living lasers made by injecting oil droplets into human cells.