title: Optimizing growth and post treatment of diamond for high capacitance neural interfaces.
abstract: Electrochemical and biological properties are two crucial criteria in the selection of the materials to be used as electrodes for neural interfaces. For neural stimulation, materials are required to exhibit high capacitance and to form intimate contact with neurons for eliciting effective neural responses at acceptably low voltages. Here we report on a new high capacitance material fabricated using nitrogen included ultrananocrystalline diamond (N-UNCD). After exposure to oxygen plasma for 3 h, the activated N-UNCD exhibited extremely high electrochemical capacitance greater than 1 mF/cm(2), which originates from the special hybrid sp(2)/sp(3) structure of N-UNCD. The in vitro biocompatibility of the activated N-UNCD was then assessed using rat cortical neurons and surface roughness was found to be critical for healthy neuron growth, with best results observed on surfaces with a roughness of approximately 20 nm. Therefore, by using oxygen plasma activated N-UNCD with appropriate surface roughness, and considering the chemical and mechanical stability of diamond, the fabricated neural interfaces are expected to exhibit high efficacy, long-term stability and a healthy neuron/electrode interface.
authors.affiliation: School of Physics, University of Melbourne, Victoria 3010, Australia.
authors.forename: Wei
authors.initials: W
authors.lastname: Tong
authors.affiliation: Centre for Additive Manufacturing, School of Engineering, RMIT University, Victoria 3001, Australia.
authors.forename: Kate
authors.initials: K
authors.lastname: Fox
authors.affiliation: Department of Anatomy and Neuroscience, University of Melbourne, Victoria 3010, Australia.
authors.forename: Akram
authors.initials: A
authors.lastname: Zamani
authors.affiliation: Department of Anatomy and Neuroscience, University of Melbourne, Victoria 3010, Australia.
authors.forename: Ann M
authors.initials: AM
authors.lastname: Turnley
authors.affiliation: School of Physics, University of Melbourne, Victoria 3010, Australia.
authors.forename: Kumaravelu
authors.initials: K
authors.lastname: Ganesan
authors.affiliation: School of Physics, University of Melbourne, Victoria 3010, Australia.
authors.forename: Arman
authors.initials: A
authors.lastname: Ahnood
authors.affiliation: School of Physics, University of Melbourne, Victoria 3010, Australia.
authors.forename: Rosemary
authors.initials: R
authors.lastname: Cicione
authors.affiliation: National Vision Research Institute, Department of Optometry and Vision Science University of Melbourne, Victoria 3010, Australia.
authors.forename: Hamish
authors.initials: H
authors.lastname: Meffin
authors.affiliation: School of Physics, University of Melbourne, Victoria 3010, Australia.
authors.forename: Steven
authors.initials: S
authors.lastname: Prawer
authors.affiliation: School of Physics, University of Melbourne, Victoria 3010, Australia.
authors.forename: Alastair
authors.initials: A
authors.lastname: Stacey
authors.affiliation: School of Physics, University of Melbourne, Victoria 3010, Australia. Electronic address: d.garrett@unimelb.edu.au.
authors.forename: David J
authors.initials: DJ
authors.lastname: Garrett
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000327:Adsorption; D000818:Animals; D002478:Cells, Cultured; D020099:Coated Materials, Biocompatible / Q000138:chemical synthesis; D003460:Crystallization / Q000379:methods*; D025802:Electric Capacitance; D004867:Equipment Design; D019544:Equipment Failure Analysis; D008422:Materials Testing; D008839:Microelectrodes; D058612:Nanodiamonds / Q000737:chemistry* / Q000648:ultrastructure*; D009474:Neurons / Q000502:physiology*; D051381:Rats
chemical_list: D020099:Coated Materials, Biocompatible; D058612:Nanodiamonds
keywords: Electrochemical capacitance; Neuron growth; Nitrogen included ultrananocrystalline diamond; Oxygen plasma; Retinal implant