Human blood laser

Laser illumination of the tumor. Illustration: Alfred Pasieka / SPL

At the word "laser", many people imagine some kind of electronic device using doped crystals, semiconductors, synthetic dyes and purified gases. Actually it is optional. Lasers can be made from ordinary biological material. In principle, working lasers can be assembled right inside the human body .

Actually, what is a laser? Some design that converts the pump energy into the energy of coherent, monochromatic, polarized and narrowly directed radiation flux. Roughly speaking, we need three things: 1) a source of energy; 2) active medium (material for signal amplification); 3) resonator (reflecting cavity).

The first laser from human cells (more precisely, from a single kidney cell) was constructed in 2011 by scientists from South Korea and the United States. As a medium for optical amplification of the signal, green fluorescent protein (GBS) was used in it. When pumping with nanosecond nanodzholevnymi pulses, individual cells generate bright directional laser radiation in a narrow band.
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A live laser from a 293ETN eukaryotic cell with expression of PBS (the cell was taken from a human kidney). Illustration: Nature Photonics, doi: 10.1038 / nphoton.2011.99

The PBS protein isolated from the jellyfish Aequorea victoria fluoresces in the green range when illuminated with blue light. It is now widely used in cellular and molecular biology to study the expression of cellular proteins. It is a completely safe protein that is injected into the patient’s blood. Thus, it can be safely used to generate laser radiation inside the human body.

Candidate of Physical Sciences Xudong (Sherman) Fan , Ann Arbor and colleagues from the University of Michigan continued the work of their predecessors. They found out that the optical signal is not only greatly enhanced by the GFB, but also by another common diagnostic dye, Indocyanine Green (ICG), if mixed with human blood cells, namely blood plasma. In this case, the ICG binds to plasma proteins and, together with them, generates an excellent, narrowly directed radiation flux. “Without blood, just ICG, the laser does not work at all,” explained Xudong Fan.



The mixture of blood with ICG is placed in a small reflective cylinder and illuminated with a conventional laser, after which the blood begins to generate bright directional laser radiation. It glows much brighter than the usual fluorescence of indocyanine, and this is important. The fact is that ICG accumulates in blood vessels, so vessels with a lot of blood - for example, tumors - will glow much brighter. Thus, it is an excellent tool for diagnosing malignant or benign tumors.

For the diagnosis, the patient should be injected with harmless indocyanine green. Then highlight the area of ​​the skin with a conventional laser (laser pointer?) - and look at this area in the infrared. By the way, ordinary digital cameras and smartphones register IR quite well - if you point the camera lens at the D / U remote from the TV, you can see the signal from the remote.

As a result, a fairly accurate diagnosis of cancer tumors is carried out using the usual things in the household - a laser pointer and a smartphone (and ICG).

To make this possible, it is necessary to bring the technology to the mind and develop safety precautions. Scientists believe that gold nanoparticles can be used as a reflecting cavity in living tissue. But another series of experiments should be carried out to determine the exact concentration of gold nanoparticles and the necessary laser power. Experiments on laser optical tomography will first conduct on animals.

“Ultimately, we will try to do it in a human body,” says the author of the scientific work. He assures that the laser power will be less than the recommended safety standards. “You don't want to fry the cloth.”

Scientific work of Professor Fan published on July 21, 2016 in the journal Optica (by the way, it was even carried on the cover of the issue), doi: 10.1364 / OPTICA.3.000809.