Researchers have developed a blood laser, using human blood and a fluorescent dye called indocyanine green (ICG), and it could help doctors search for tumours in the body.
So how does this new ‘blood laser’ work? To make a laser, all you need is a source of light, an amplifying material, and a reflective cavity. Researchers from the University of Michigan used an FDA-approved dye called ICG, and mixed it with the blood to play the role of the amplifier.
"Without blood, just ICG, it doesn’t work at all," one of the researchers, Xudong Fan, told Jacob Aron at New Scientist.
Once you have your cavity, an amplifying material, and source of light, your laser is in business.
"Then photons are pumped into the cavity. If one
strikes an excited atom, that atom will drop back down to its ground
state, releasing a second photon of the same frequency and direction," she says.
Eventually, these continue striking other energised atoms, releasing more protons until they create a burst of laser light. When Fan and his team placed the blood and ICG in a reflective cylinder, and shot at with a near-infrared light beam, the blood emitted light, creating a potential new technique for doctors use to search for tumours.
Because ICG accumulates in blood vessels, areas with large
amounts of blood vessels, like tumours, should light up like a Christmas
tree. The technique would simply involve injecting the ICG into the
patient, and shining a light beam at the skin, while checking an
infrared camera for the glow.
The blood laser has yet to be tested in live animal tissue,
because they have to figure out what will play the role of the
reflective cavity. But Fan says that gold nanoparticles could be useful
for the job.
"Eventually, we are trying to do it in the human body," he told New Scientist, adding that they need to figure out how to ensure that the light produced by the blood laser isn’t too strong.
"You don’t want to burn the tissue," he said.
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