Nanoporous Gold as a Neural Interface Coating: Effects of Topography, Surface Chemistry, and Feature Size

• Published in: ACS applied materials & interfaces Vol. 7; no. 13; pp. 7093 - 7100
• Main Authors: Chapman, Christopher A. R, Chen, Hao, Stamou, Marianna, Biener, Juergen, Biener, Monika M, Lein, Pamela J, Seker, Erkin
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 08-04-2015; American Chemical Society (ACS)
• Subjects: Animals; Cell Proliferation - physiology; Cells, Cultured; cell−material interaction; Coated Materials, Biocompatible - chemical synthesis; Electric Conductivity; Electrodes, Implanted; Equipment Design; Equipment Failure Analysis; gliosis; Gold - chemistry; MATERIALS SCIENCE; Materials Testing; Metal Nanoparticles - chemistry; Metal Nanoparticles - ultrastructure; Microelectrodes; multifunctional biomaterial; Nanopores - ultrastructure; nanoporous gold; nanostructure; nanotopography; neural electrode; Neurons - physiology; neuron−astrocyte co-culture; Particle Size; Rats; cell−material interaction; nanoporous gold; neural electrode; neuron−astrocyte co-culture; nanostructure; nanotopography; multifunctional biomaterial; gliosis
• ISSN: 1944-8244; 1944-8252
• DOI: 10.1021/acsami.5b00410

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.