Organic electronics for precise delivery of neurotransmitters

Sammanfattning: Organic electronic materials, that is, carbon-based compounds that conduct electricity, haveemerged as candidates for improving the interface between conventional electronics andbiological systems. The softness of these materials matches the elasticity of biological tissuebetter than conventional electronic conductors, allowing better contact to tissue, and the mixedionic-electronic conductivity can improve the signal transduction between electronic devices andelectrically excitable cells. This improved communication between electronics and tissue cansignificantly enhance, for example, electrical stimulation for therapy and electrical recording fordiagnostics.The ionic conductivity of organic electronic materials makes it possible to achieve ion-specificionic currents, where the current consists of migration of specific ions. These ions can be chargedsignalling substances, such as neurotransmitters, that can selectively activate or inhibit cells thatcontain receptors for these substances. This thesis describes the development of chemical deliverydevices, where delivery is based on such ion-specific currents through ionically and electronicallyconducting polymers. Delivery is controlled by electrical signals, and allows release of controlledamounts of neurotransmitters, or other charged compounds, to micrometer-sized regions.The aims of the thesis have been to improve spatial control and temporal resolution of chemicaldelivery, with the ultimate goal of selective interaction with individual cells, and to enable futuretherapies for disorders of the nervous system. Within the thesis, we show that delivery canalleviate pain through local delivery to specific regions of the spinal cord in an animal model ofneuropathic pain, and that epilepsy-related signalling can be suppressed in vitro. We also integratethe delivery device with electrodes for sensing, to allow simultaneous electrical recording anddelivery at the same position. Finally, we improve the delay from electrical signal to chemicaldelivery, approaching the time domain of synaptic signaling, and construct devices with severalindividually controlled release sites.