title: Organic bioelectronics for electronic-to-chemical translation in modulation of neuronal signaling and machine-to-brain interfacing.
abstract: BACKGROUND
  A major challenge when creating interfaces for the nervous system is to translate between the signal carriers of the nervous system (ions and neurotransmitters) and those of conventional electronics (electrons).
  
  
  METHODS
  Organic conjugated polymers represent a unique class of materials that utilizes both electrons and ions as charge carriers. Based on these materials, we have established a series of novel communication interfaces between electronic components and biological systems. The organic electronic ion pump (OEIP) presented in this review is made of the polymer-polyelectrolyte system poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS). The OEIP translates electronic signals into electrophoretic migration of ions and neurotransmitters.
  
  
  CONCLUSIONS
  We demonstrate how spatio-temporally controlled delivery of ions and neurotransmitters can be used to modulate intracellular Ca(2+) signaling in neuronal cells in the absence of convective disturbances. The electronic control of delivery enables strict control of dynamic parameters, such as amplitude and frequency of Ca(2+) responses, and can be used to generate temporal patterns mimicking naturally occurring Ca(2+) oscillations. To enable further control of the ionic signals we developed the electrophoretic chemical transistor, an analog of the traditional transistor used to amplify and/or switch electronic signals. Finally, we demonstrate the use of the OEIP in a new "machine-to-brain" interface by modulating brainstem responses in vivo.
  
  
  CONCLUSIONS
  This review highlights the potential of communication interfaces based on conjugated polymers in generating complex, high-resolution, signal patterns to control cell physiology. We foresee widespread applications for these devices in biomedical research and in future medical devices within multiple therapeutic areas. This article is part of a Special Issue entitled Organic Bioelectronics-Novel Applications in Biomedicine.
authors.affiliation: Swedish Medical Nanoscience Center, Department of Neuroscience, Karolinska Institutet, SE-171 77 Stockholm, Sweden.
authors.forename: Karin C
authors.initials: KC
authors.lastname: Larsson
authors.forename: Peter
authors.initials: P
authors.lastname: Kjäll
authors.forename: Agneta
authors.initials: A
authors.lastname: Richter-Dahlfors
mesh_terms: D001921:Brain / Q000187:drug effects* / Q000502:physiology*; D062207:Brain-Computer Interfaces; D004582:Electronics, Medical / Q000379:methods*; D006801:Humans; D007477:Ions / Q000378:metabolism; D009474:Neurons / Q000187:drug effects* / Q000502:physiology*; D018377:Neurotransmitter Agents / Q000378:metabolism; D011137:Polystyrenes; D015398:Signal Transduction; D013876:Thiophenes; D014173:Transistors, Electronic
chemical_list: D007477:Ions; D018377:Neurotransmitter Agents; D011137:Polystyrenes; D013876:Thiophenes; C533756:poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate)