title: Coatings of nanostructured pristine graphene-IrOx hybrids for neural electrodes: Layered stacking and the role of non-oxygenated graphene.
abstract: The need to enhance charge capacity in neural stimulation-electrodes is promoting the formation of new materials and coatings. Among all the possible types of graphene, pristine graphene prepared by graphite electrochemical exfoliation, is used in this work to form a new nanostructured IrOx-graphene hybrid (IrOx-eG). Graphene is stabilized in suspension by IrOx nanoparticles without surfactants. Anodic electrodeposition results in coatings with much smaller roughness than IrOx-graphene oxide. Exfoliated pristine graphene (eG), does not electrodeposit in absence of iridium, but IrOx-nanoparticle adhesion on graphene flakes drives the process. IrOx-eG has a significantly different electronic state than graphene oxide, and different coordination for carbon. Electron diffraction shows the reflection features expected for graphene. IrOx 1-2 nm cluster/nanoparticles are oxohydroxo-species and adhere to 10nm graphene platelets. eG induces charge storage capacity values five times larger than in pure IrOx, and if calculated per carbon atom, this enhancement is one order magnitude larger than the induced by graphene oxide. IrOx-eG coatings show optimal in vitro neural cell viability and function as cell culture substrates. The fully straightforward electrochemical exfoliation and electrodeposition constitutes a step towards the application of graphene in biomedical systems, expanding the knowledge of pristine graphene vs. graphene oxide, in bioelectrodes.
authors.affiliation: Institut Ciència de Materials de Barcelona (ICMAB-CSIC), Campus UAB, E-08193, Bellaterra, Barcelona, Spain.
authors.forename: E
authors.initials: E
authors.lastname: Pérez
authors.affiliation: Institut d'Investigacions Biomèdiques de Barcelona (IIBB-CSIC), Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), c/Rosselló 161, 08036 Barcelona, Spain.
authors.forename: M P
authors.initials: MP
authors.lastname: Lichtenstein
authors.affiliation: Institut d'Investigacions Biomèdiques de Barcelona (IIBB-CSIC), Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), c/Rosselló 161, 08036 Barcelona, Spain.
authors.forename: C
authors.initials: C
authors.lastname: Suñol
authors.affiliation: Institut Ciència de Materials de Barcelona (ICMAB-CSIC), Campus UAB, E-08193, Bellaterra, Barcelona, Spain. Electronic address: nieves@icmab.es.
authors.forename: N
authors.initials: N
authors.lastname: Casañ-Pastor
mesh_terms: D000818:Animals; D002470:Cell Survival; D002478:Cells, Cultured; D020099:Coated Materials, Biocompatible; D004558:Electric Stimulation / Q000295:instrumentation*; D004563:Electrochemistry / Q000379:methods; D004566:Electrodes; D006108:Graphite / Q000737:chemistry; D007495:Iridium / Q000737:chemistry; D008422:Materials Testing; D008815:Mice, Inbred Strains; D049329:Nanostructures / Q000737:chemistry*; D009474:Neurons / Q000166:cytology / Q000502:physiology*; D013499:Surface Properties
chemical_list: D020099:Coated Materials, Biocompatible; D007495:Iridium; D006108:Graphite
keywords: Electrodeposition; Iridium oxide nanoparticles electroactive coatings; Layered nanostructure; Neural electrode; Pristine graphene