The Roles of an Aluminum Underlayer in the Biocompatibility and Mechanical Integrity of Vertically Aligned Carbon Nanotubes for Interfacing with Retinal Neurons

William J. Watterson; Saba Moslehi; Conor Rowland; Kara M. Zappitelli; Julian H. Smith; David Miller; Julie E. Chouinard; Stephen L. Golledge; Richard P. Taylor; Maria-Thereza Perez; Benjamín J. Alemán

doi:10.3390/mi11060546

Micromachines (May 2020)

The Roles of an Aluminum Underlayer in the Biocompatibility and Mechanical Integrity of Vertically Aligned Carbon Nanotubes for Interfacing with Retinal Neurons

William J. Watterson,
Saba Moslehi,
Conor Rowland,
Kara M. Zappitelli,
Julian H. Smith,
David Miller,
Julie E. Chouinard,
Stephen L. Golledge,
Richard P. Taylor,
Maria-Thereza Perez,
Benjamín J. Alemán

Affiliations

William J. Watterson: Physics Department, University of Oregon, Eugene, OR 97403, USA
Saba Moslehi: Physics Department, University of Oregon, Eugene, OR 97403, USA
Conor Rowland: Physics Department, University of Oregon, Eugene, OR 97403, USA
Kara M. Zappitelli: Physics Department, University of Oregon, Eugene, OR 97403, USA
Julian H. Smith: Physics Department, University of Oregon, Eugene, OR 97403, USA
David Miller: Physics Department, University of Oregon, Eugene, OR 97403, USA
Julie E. Chouinard: Center for Advanced Materials Characterization in Oregon, University of Oregon, Eugene, OR 97403, USA
Stephen L. Golledge: Center for Advanced Materials Characterization in Oregon, University of Oregon, Eugene, OR 97403, USA
Richard P. Taylor: Physics Department, University of Oregon, Eugene, OR 97403, USA
Maria-Thereza Perez: Department of Clinical Sciences Lund, Division of Ophthalmology, Lund University, SE-221 84 Lund, Sweden
Benjamín J. Alemán: Physics Department, University of Oregon, Eugene, OR 97403, USA

DOI: https://doi.org/10.3390/mi11060546
Journal volume & issue: Vol. 11, no. 6
p. 546

Abstract

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Retinal implant devices are becoming an increasingly realizable way to improve the vision of patients blinded by photoreceptor degeneration. As an electrode material that can improve restored visual acuity, carbon nanotubes (CNTs) excel due to their nanoscale topography, flexibility, surface chemistry, and double-layer capacitance. If vertically aligned carbon nanotubes (VACNTs) are biocompatible with retinal neurons and mechanically robust, they can further improve visual acuity—most notably in subretinal implants—because they can be patterned into high-aspect-ratio, micrometer-size electrodes. We investigated the role of an aluminum (Al) underlayer beneath an iron (Fe) catalyst layer used in the growth of VACNTs by chemical vapor deposition (CVD). In particular, we cultured dissociated retinal cells for three days in vitro (DIV) on unfunctionalized and oxygen plasma functionalized VACNTs grown from a Fe catalyst (Fe and Fe+Pl preparations, where Pl signifies the plasma functionalization) and an Fe catalyst with an Al underlayer (Al/Fe and Al/Fe+Pl preparations). The addition of the Al layer increased the mechanical integrity of the VACNT interface and enhanced retinal neurite outgrowth over the Fe preparation. Unexpectedly, the extent of neurite outgrowth was significantly greater in the Al/Fe than in the Al/Fe+Pl preparation, suggesting plasma functionalization can negatively impact biocompatibility for some VACNT preparations. Additionally, we show our VACNT growth process for the Al/Fe preparation can support neurite outgrowth for up to 7 DIV. By demonstrating the retinal neuron biocompatibility, mechanical integrity, and pattern control of our VACNTs, this work offers VACNT electrodes as a solution for improving the restored visual acuity provided by modern retinal implants.

Published in Micromachines

ISSN: 2072-666X (Online)
Publisher: MDPI AG
Country of publisher: Switzerland
LCC subjects: Technology: Mechanical engineering and machinery
Website: https://www.mdpi.com/journal/micromachines

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