If successful in future tests, the gel could one day replace conventional materials that help restore brain, eye, ear, spinal cord, nerve and muscle functions
The fish also appeared normal during the study, suggesting the gel (shown in the photo) could be safe. Photo: Thor Balkhed.
Researchers, for the first time, have used the body’s own chemistry to develop electrodes in the tissues of zebrafish (a small freshwater fish). They used the body sugars of the fish to transform an injectable gel into a flexible electrode while causing no damage to the tissues of the organism.
The gel turned into an electrically conducting material within the living tissues of zebrafish, according to the findings of the research published in the journal Science on February 23, 2023.
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If successful in future tests, the gel could one day replace conventional materials that help restore brain, eye, ear, spinal cord, nerve and muscle functions. It could also help treat Parkinson’s disease, epilepsy, dystonia (a movement disorder) and depression.
The gel could also lead to the development of human-machine interface in the future, noted the study.
Conventional materials are often incompatible with living tissues, affecting their lifetime and efficacy. They could also trigger the immune response, leading to complications.
When the gel was injected into the zebrafish’s brain and tailfin, sugars in the body transformed the inactive gel into an electrode, a device that conducts electricity.
In previous experiments, researchers have had to rely on techniques that modify genes or use light or electrical energy to trigger electrode formation.
“For several decades, we have tried to create electronics that mimic biology. Now we let biology create the electronics for us,” Magnus Berggren from Linköping University and one of the study’s authors, said in a statement.
Unlike animals, plant cells facilitate the formation of electrodes due to their rigid cell wall. On the other hand, animal cells are soft, preventing electrodes from forming spontaneously.
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The gel is built from a mixture of chemicals and enzymes, which are inactive. Interactions with body sugars such as lactose and glucose induce them to become electrically conductive.
The injected solution turned dark blue from yellow in seconds. “By making smart changes to the chemistry, we were able to develop electrodes that were accepted by the brain tissue and immune system, said Roger Olsson, professor at the medical faculty, Lund University.
The team injected the gel into the brain of nine anaesthetised zebrafish. Next, they were allowed to swim for three hours.
The fish, the researchers said, suffered no mortalities. They were no observable changes to the swimming behaviour or general appearance, they added.
The researchers extracted the hearts of the fish and placed them into the gel. Activation of the gel was restricted to specific regions. This likely occurred in regions where glucose or lactate are exchanged, the researchers speculated.
The gel was also tested in leeches and muscle tissues of cows, pigs and chickens, showing encouraging results. These findings, according to the study, pave the way for creating soft electronics in various biological tissues and environments. The researchers said they still need to solve a range of problems, but the study provides a good start.
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