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• Posted February 24, 2023

Scientists Grow Electrodes in Living Tissue

Swedish scientists say they have grown electrodes in living tissue, paving the way for formation of fully integrated electronic circuits in living organisms.

The development, which blurs the lines between biology and technology, could one day lead to therapies for neurological disorders.

"For several decades, we have tried to create electronics that mimic biology. Now we let biology create the electronics for us," researcher Magnus Berggren said in a news release from Linköping University in Sweden. He's a professor in the Laboratory for Organic Electronics at the university.

Conventional bioelectronics are difficult, if not impossible, to combine with living biological signal systems.

To address this, researchers developed a method for creating soft, electronically conductive materials in living tissue.

They injected a gel containing enzymes as the "assembly molecules,"and then were able to grow electrodes in the tissue of zebrafish and medicinal leeches.

"Contact with the body's substances changes the structure of the gel and makes it electrically conductive, which it isn't before injection. Depending on the tissue, we can also adjust the composition of the gel to get the electrical process going,"said Xenofon Strakosas, one of the study's leaders. He's also researcher at Linköping's Laboratory for Organic Electronics and at Lund University in Sweden.

The body's own endogenous molecules are enough to trigger the formation of electrodes, researchers said.

Neither genetic modification nor external signals, such as light or electrical energy, which had been necessary in previous experiments, are required.

Researchers said this work paves the way for a new path in bioelectronics.

This method can target the electronically conducting material to specific biological structures. With this they can create an interface for nerve stimulation.

Eventually, fabricating fully integrated electronic circuits in living organisms may be possible, according to the study.

At Lund University, the team successfully achieved electrode formation in the brain, heart and tail fins of zebrafish and around the nervous tissue of medicinal leeches.

The animals were not harmed by the injected gel, according to the study. They were not otherwise affected by the electrode formation.

The authors said one of the many challenges in these trials was taking animals' immune system into account.

"By making smart changes to the chemistry, we were able to develop electrodes that were accepted by the brain tissue and immune system. The zebrafish is an excellent model for the study of organic electrodes in brains,"said researcher Roger Olsson, a professor of chemical biology and therapeutics at Lund University.

Olsson launched the study after reading about an electronic rose developed at Linköping University in 2015.

An important difference between plants and animals was in cell structure. Plants have rigid cell walls that allow for formation of electrodes. Animal cells are more like a soft mass.

Creating a gel with enough structure and the right combination of substances to form electrodes in such surroundings took many years to do, the authors noted.

"Our results open up for completely new ways of thinking about biology and electronics. We still have a range of problems to solve, but this study is a good starting point for future research,"said Hanne Biesmans, a doctoral student at Linkoping University who is one of the study's leaders.

While research in animals does not always produce the same results in humans, these findings could aid in understanding of complex biological functions, combating diseases in the brain and developing future interfaces between man and machine, according to the study.

The findings were recently published in the journal Science.

More information

The World Health Organization has more on neurological disorders.

SOURCE: Linköping University, news release, Feb. 23, 2023