Our nerve and muscle cells send signals to each other using ions and molecules. Certain substances, such as the neurotransmitter GABA (gamma aminobutyric acid), are important signal substances throughout the central nervous system.
Eighteen months ago, researchers at the Laboratory of Organic Electronics demonstrated an ion pump which researchers at the Karolinska Institutet could use to reduce the sensation of pain in awake, freely-moving rats. The ion pump delivered GABA directly to the rat's spinal cord. The researchers findings on delivering the body's own neurotransmitters was published in Science Advances and created interest around the world.
Now the research group at the Laboratory of Organic Electronics has made another advance and developed a significantly smaller and more rapid ion pump that transmits signals nearly as rapidly as the cells themselves, and with a precision on the scale of an individual cell. The findings have been published in Science Advances.
Amanda Jonsson, who together with Theresia Arbring Sjöström is principal author of the article in Science Advances, has developed the pain-alleviating ion pump as part of her doctoral studies. She proudly presents a glass disk with many of the new miniaturised ion pumps. Some pumps have only a single outlet, but others have six tiny point outlets.
The new ion pump has so far only been tested in the laboratory. The next step will be to test it with live cells and the researchers hope eventually to, for example alleviate pain, stop epileptic seizures, and reduce the symptoms of Parkinsons disease, using exactly the required dose at exactly the affected cells. Communication using the cell´s own language, and the cell's own speed.
Figure: Linkoping University - The ion pump beside a swedish coin, 10 Skr
All of the outputs of the ion pump can also be rapidly switched on or off with the aid of micrometre-sized ion diodes.
Organic electronic components have a major advantage here: 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.
The ion diode has recently been developed, as has the material that forms the basis of the new rapid ion pump.
The research has been financed by the Knut and Alice Wallenberg Foundation, the Swedish Research Council, and Vinnova.
Magnus Berggren, professor of organic electronics and director of the Laboratory of Organic Electronics, said, "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. When a signal passes between two synapses it takes 1-10 milliseconds, and we are now very close to the nervous system's own speed." Magnus continued, "We conclude that we have produced artificial nerves that can communicate seamlessly with the nervous system. After more than 10 years' research we have finally got all the parts of the puzzle in place."
Amanda Jonsson, said, "We can make them with several outlets, it's just as easy as making one. And all of the outlets can be individually controlled. Previously we could only transport ions horizontally and from all outputs at the same time. Now, however, we can deliver the ions vertically, which makes the distance they have to be transported as short as a micrometre."
Theresia Arbring Sjöström, said, "The ions are released rapidly by an electrical signal, in the same way that the neurotransmitter is released in a synapse."
Daniel Simon, said, "The new material makes it possible to build with a precision and reliability not possible in previous versions of the ion pump."
Amanda Jonsson | Theresia Arbring Sjöström | Klas Tybrandt | Magnus Berggren | Daniel T. Simon
Science Advances 02 Nov 2016: | Vol. 2, no. 11, e1601340 | DOI: 10.1126/sciadv.1601340
Technologies that restore or augment dysfunctional neural signaling represent a promising route to deeper understanding and new therapies for neurological disorders. Because of the chemical specificity and subsecond signaling of the nervous system, these technologies should be able to release specific neurotransmitters at specific locations with millisecond resolution. We have previously demonstrated an organic electronic lateral electrophoresis technology capable of precise delivery of charged compounds, such as neurotransmitters. However, this technology, the organic electronic ion pump, has been limited to a single delivery point, or several simultaneously addressed outlets, with switch-on speeds of seconds. We report on a vertical neurotransmitter delivery device, configured as an array with individually controlled delivery points and a temporal resolution of 50 ms. This is achieved by supplementing lateral electrophoresis with a control electrode and an ion diode at each delivery point to allow addressing and limit leakage. By delivering local pulses of neurotransmitters with spatiotemporal dynamics approaching synaptic function, the high-speed delivery array promises unprecedented access to neural signaling and a path toward biochemically regulated neural prostheses.