A new application of graphene
With the help of light, cells grown on a graphene substrate can be controlled
Maria Perepechaeva, "First-hand Science"
Graphene is a "two–dimensional" crystalline carbon material with a thickness of only one atom, due to its unique properties, it is widely used today in a variety of fields, from electronics to medicine. Recently, on the basis of this revolutionary material, a technology has been developed that allows changing the rate of contraction of heart muscle cells by a light "command".
Electricity plays an important role in the physiology of the cell, responsible for its excitability (the ability to respond to a variety of stimuli), the constancy of the ionic composition, etc.
It is possible to influence the electrical activity of cells by changing the membrane potential, which is the difference between the values of the electric charge on the inner and outer sides of the cell membrane, thus it is possible to control the functions of cells and, as a consequence, the activity of an entire organ. The only problem is how to do it without harming the body. After all, the implantation of electrodes causes serious injury, which is not welcome in medical practice, and the technology of optogenetic stimulation requires the introduction of foreign genes, which is unacceptable so far.
In search of an alternative, an international group of researchers led by specialists from the University of California at San Diego (USA) turned to graphene. The scientists worked with human cardiomyocytes – heart muscle cells obtained by reprogramming from skin epithelial cells. As you know, cell cultures are usually grown in plastic petri dishes or on glass plates. However, glass and plastic are insulators, and when scientists tried to grow cardiomyocytes on glass plates coated with semi–conductive graphene, it turned out that in such conditions they grow better, and their "behavior" becomes closer to natural.
But the most important thing was ahead. As you know, graphene not only conducts an electric current, but is also able to convert light incident on it into electricity: photons, falling on graphene, are able to knock free electrons out of carbon atoms. By directing light of varying intensity onto the glass plate, the researchers were able to influence the electrical activity of cardiomyocytes, causing them to contract faster or slower!
At the same time, graphene turned out to be a non–toxic material, which was confirmed by experiments on a convenient model - transparent embryos of danio rerio fish. At least, after injection of graphene solution into three-day embryos for 3 days, no negative effects were found. And by acting with light, it was possible to accelerate the beating of the developing heart of the embryos.
The graphene/light system can be used to create pacemakers that will be safer and more effective than existing ones. But still, it will be most in demand, apparently, for the development of new drugs. Today, at the initial stages of such a search, hundreds of thousands of different chemical compounds are tested on cells, but there is always a risk of missing a potential drug if its effect cannot manifest itself under standard cultivation conditions. For example, in culture, cardiomyocytes shrink at their own pace, but during a heart attack, this rate may be completely different!
This idea was confirmed in an experiment when the antiarrhythmic drug mexiletin was added to the culture of cardiomyocytes, acting only with an increase in heart rate. By illuminating the cells with light of varying intensity to regulate the contractions of cardiocytes, the scientists found that the faster they contracted, the better the effect of mexiletin was noticeable.
In the future, the researchers plan to use the graphene/light system to search for antitumor drugs that selectively destroy only cancer cells, as well as to search for selectively acting opioid-type painkillers, which would help avoid addiction.
And although there is still a lot of work to be done in this direction, scientists believe that "the sheepskin is worth the effort", because a day of experiments on cells "living" on graphene can replace six months of experimentation on laboratory animals.
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