he invention, which opens new avenues for controlling chemical signals, is being published in the coming issue of the highly ranked scientific journal PNAS. The authors are Klas Tybrandt and Magnus Berggren of Linköping University, who developed the invention, and Karin Larsson and Agneta Richter-Dahlfors at the Karolinska Institute, who have used it in experiments with cultivated nerve cells.
The four scientists work at the OBOE Research Center, which is dedicated to the study and regulation of processes in living cells and tissue through the use of organic electronics.
Previously use has been made of nano-canals and nano-pores to actively control the concentration and transport of ions. But such components are difficult to produce and moreover function poorly when the salt content is high, which is a precondition in interaction with biological systems.
"To get around these problems, we exploited the similarity between ion-selective membranes – plastics that only conduct ions of one charge – and doped semiconductors, such as silicon. It was previously known that it is possible to produce diodes from such membranes. We took it a step further by joining two ion diodes into a transistor," says Klas Tybrandt, a doctoral candidate in organic electronics.
When an ion transistor was connected to cultivated nerve cells, it could be used to control the supply of the signal substance acetylcholin locally to the cells. The successful result demonstrates both that the component functions together with biological systems and that even tiny charged biomolecules can be transported without difficulty.
"Since the ion transistor is made of plastic, it can be integrated with other components we are developing. This means we can make use of inexpensive printing processes on flexible materials. We believe ion transistors will play a major role in various applications, such as the controlled delivery of drugs, lab-on-a-chip and sensors," says Magnus Berggren, Önnesjö professor of organic electronics.
Article: Ion bipolar junction transistors by Klas Tybrandt, Karin C. Larsson, Agneta Richter-Dahlfors, and Magnus Berggren, PNAS Ahead of print May 17 2010.
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