title: Electrophoretic deposition of ligand-free platinum nanoparticles on neural electrodes affects their impedance in vitro and in vivo with no negative effect on reactive gliosis.
abstract: BACKGROUND
  Electrodes for neural stimulation and recording are used for the treatment of neurological disorders. Their features critically depend on impedance and interaction with brain tissue. The effect of surface modification on electrode impedance was examined in vitro and in vivo after intracranial implantation in rats. Electrodes coated by electrophoretic deposition with platinum nanoparticles (NP; <10 and 50 nm) as well as uncoated references were implanted into the rat's subthalamic nucleus. After postoperative recovery, rats were electrostimulated for 3 weeks. Impedance was measured before implantation, after recovery and then weekly during stimulation. Finally, local field potential was recorded and tissue-to-implant reaction was immunohistochemically studied.
  
  
  RESULTS
  Coating with NP significantly increased electrode's impedance in vitro. Postoperatively, the impedance of all electrodes was temporarily further increased. This effect was lowest for the electrodes coated with particles <10 nm, which also showed the most stable impedance dynamics during stimulation for 3 weeks and the lowest total power of local field potential during neuronal activity recording. Histological analysis revealed that NP-coating did not affect glial reactions or neural cell-count.
  
  
  CONCLUSIONS
  Coating with NP <10 nm may improve electrode's impedance stability without affecting biocompatibility. Increased impedance after NP-coating may improve neural recording due to better signal-to-noise ratio.
authors.affiliation: Department of Neurosurgery, Hannover Medical School, Medical University Hannover, Carl-Neuberg-Str. 1, 30625, Hannover, Germany. angelov.svilen@mh-hannover.de.
authors.forename: Svilen D
authors.initials: SD
authors.lastname: Angelov
authors.affiliation: Technical Chemistry I and Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, Universitätsstrasse 7, 45141, Essen, Germany. sven.koenen@uni-due.de.
authors.forename: Sven
authors.initials: S
authors.lastname: Koenen
authors.affiliation: Technical Chemistry I and Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, Universitätsstrasse 7, 45141, Essen, Germany. jurij.jakobi@uni-due.de.
authors.forename: Jurij
authors.initials: J
authors.lastname: Jakobi
authors.affiliation: Department of Neurosurgery, Hannover Medical School, Medical University Hannover, Carl-Neuberg-Str. 1, 30625, Hannover, Germany. heissler.hans.e@mh-hannover.de.
authors.forename: Hans E
authors.initials: HE
authors.lastname: Heissler
authors.affiliation: Department of Neurosurgery, Hannover Medical School, Medical University Hannover, Carl-Neuberg-Str. 1, 30625, Hannover, Germany. alam.mesbah@mh-hannover.de.
authors.forename: Mesbah
authors.initials: M
authors.lastname: Alam
authors.affiliation: Department of Neurosurgery, Hannover Medical School, Medical University Hannover, Carl-Neuberg-Str. 1, 30625, Hannover, Germany. schwabe.kerstin@mh-hannover.de.
authors.forename: Kerstin
authors.initials: K
authors.lastname: Schwabe
authors.affiliation: Technical Chemistry I and Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, Universitätsstrasse 7, 45141, Essen, Germany. stephan.barcikowski@uni-due.de.
authors.forename: Stephan
authors.initials: S
authors.lastname: Barcikowski
authors.affiliation: Department of Neurosurgery, Hannover Medical School, Medical University Hannover, Carl-Neuberg-Str. 1, 30625, Hannover, Germany. krauss.joachim@mh-hannover.de.
authors.forename: Joachim K
authors.initials: JK
authors.lastname: Krauss
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000008:administration & dosage; D001921:Brain / Q000187:drug effects; D017097:Electric Impedance / Q000627:therapeutic use*; D004867:Equipment Design / Q000379:methods; D005911:Gliosis / Q000628:therapy*; D008024:Ligands; D008297:Male; D008839:Microelectrodes; D053758:Nanoparticles / Q000008:administration & dosage* / Q000737:chemistry*; D009474:Neurons / Q000187:drug effects*; D010984:Platinum / Q000008:administration & dosage* / Q000737:chemistry*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D001672:Biocompatible Materials; D008024:Ligands; D010984:Platinum