title: Nanoporous gold as a neural interface coating: effects of topography, surface chemistry, and feature size.
abstract: Designing neural interfaces that maintain close physical coupling of neurons to an electrode surface remains a major challenge for both implantable and in vitro neural recording electrode arrays. Typically, low-impedance nanostructured electrode coatings rely on chemical cues from pharmaceuticals or surface-immobilized peptides to suppress glial scar tissue formation over the electrode surface (astrogliosis), which is an obstacle to reliable neuron-electrode coupling. Nanoporous gold (np-Au), produced by an alloy corrosion process, is a promising candidate to reduce astrogliosis solely through topography by taking advantage of its tunable length scale. In the present in vitro study on np-Au's interaction with cortical neuron-glia co-cultures, we demonstrate that the nanostructure of np-Au achieves close physical coupling of neurons by maintaining a high neuron-to-astrocyte surface coverage ratio. Atomic layer deposition-based surface modification was employed to decouple the effect of morphology from surface chemistry. Additionally, length scale effects were systematically studied by controlling the characteristic feature size of np-Au through variations in the dealloying conditions. Our results show that np-Au nanotopography, not surface chemistry, reduces astrocyte surface coverage while maintaining high neuronal coverage and may enhance neuron-electrode coupling through nanostructure-mediated suppression of scar tissue formation.
authors.forename: Christopher A R
authors.initials: CA
authors.lastname: Chapman
authors.forename: Hao
authors.initials: H
authors.lastname: Chen
authors.forename: Marianna
authors.initials: M
authors.lastname: Stamou
authors.affiliation: §Lawrence Livermore National Laboratory, Livermore, California 94551, United States.
authors.forename: Juergen
authors.initials: J
authors.lastname: Biener
authors.affiliation: §Lawrence Livermore National Laboratory, Livermore, California 94551, United States.
authors.forename: Monika M
authors.initials: MM
authors.lastname: Biener
authors.forename: Pamela J
authors.initials: PJ
authors.lastname: Lein
authors.forename: Erkin
authors.initials: E
authors.lastname: Seker
mesh_terms: D000818:Animals; D049109:Cell Proliferation / Q000502:physiology; D002478:Cells, Cultured; D020099:Coated Materials, Biocompatible / Q000138:chemical synthesis*; D004553:Electric Conductivity; D004567:Electrodes, Implanted; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006046:Gold / Q000737:chemistry*; D008422:Materials Testing; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D008839:Microelectrodes; D058608:Nanopores / Q000648:ultrastructure*; D009474:Neurons / Q000502:physiology*; D010316:Particle Size; D051381:Rats
chemical_list: D020099:Coated Materials, Biocompatible; D006046:Gold
keywords: cell−material interaction; gliosis; multifunctional biomaterial; nanoporous gold; nanostructure; nanotopography; neural electrode; neuron−astrocyte co-culture