Bioelectronic ion pump delivers neurotransmitters within the body

Researchers from Linköping University’s Laboratory of Organic Electronics have developed a microfabricated ion pump, built from organic electronic components, that transmits signals nearly as rapidly and precisely as cells themselves.

The achievement builds on the laboratory’s previous work, which saw an ion pump used to deliver the neurotransmitter GABA (gamma aminobutyric acid) into the spinal cords of rats in order to reduce the sensation of pain. Both studies have now been published in the journal Science Advances.

“Our skilled doctoral students, Amanda Jonsson and Theresia Arbring Sjöström, have succeeded with the last important part of the puzzle in the development of the ion pump,” said Magnus Berggren, director of the Laboratory of Organic Electronics. “When a signal passes between two synapses it takes 1-10 ms, and we are now very close to the nervous system’s own speed.

“We conclude that we have produced artificial nerves that can communicate seamlessly with the nervous system.”

Jonsson developed the pain-alleviating ion pump together with Sjöström as part of her doctoral studies. Some of her pumps have only a single outlet, while others have six. Each outlet has been provided with a control electrode made from a conducting polymer, which means that they can be individually controlled.

“Previously, we could only transport ions horizontally and from all outputs at the same time,” said Jonsson. “Now, however, we can deliver the ions vertically, which makes the distance they have to be transported as short as a micrometre.”

Amanda Jonsson, Daniel Simon and Theresia Arbring Sjöström working at the Laboratory of Organic Electronics, Linköping University. Image credit:Thor Balkhed/LiU

The control electrode together with another material forms an ion diode, which prevents leakage and can be used to switch the outputs on or off. The conducting polymer in the control electrode becomes charged with ions when the pump is switched off. The ions can be rapidly released when an electrical signal is received, in the same way that an action potential causes neurotransmitter to be released in a synapse.

Organic electronic components have a major advantage in that they can conduct both ions and electricity. In this case, the material PEDOT:PSS enables the electrical signals to be converted to chemical signals that the body understands. According to study co-author Daniel Simon, “The new material makes it possible to build with a precision and reliability not possible in previous versions of the ion pump.”

The new ion pump has so far only been tested in the laboratory; the next step will be to test it with live cells. Eventually, the researchers hope it will be used to alleviate pain, stop epileptic seizures and reduce the symptoms of Parkinson’s disease, delivering exactly the required dose to exactly the affected cells.

Top image: The six-outlet pump sits beside a Swedish coin. Image credit: Thor Balkhed/LiU