gms | German Medical Science

Background: To analyze the biocompatibility of distinct multiwalled carbon nanotubes (MWCNT) in order to optimize microelectrode properties related to charge transfer capacity and signal-to-noise ratio.

Methods: Vertically aligned MWCNT were synthesized on 4-inch silicon wafers by chemical vapor deposition and growth was achieved by nanoscale layers of iron, iron-platinum, or iron-titanium acting as catalysts. Survival, growth rate, and gene expression profile of L-929 and retinal precursor (R28) cells were estimated after direct contact as well as indirect contact, which means cultivation in cell culture medium pre-incubated with MWCNT-coated wafer pieces.

Results: Indirect contact had no significant influence on cell growth rates, measured in comparison to reference materials that exhibited defined levels of toxicity. Both cell types exhibited good proliferation properties on each MWCNT-coated silicon wafer. Cell viability ranged from 94.6% to 99.1%, in which better survival was shown on wafer pieces generated with the catalyst mixtures than with the iron catalyst alone. However, R28 cells exhibited a more separated growth, which may be explained by the rather hydrophobic property of the MWCNT surface, and showed a slightly decreased expression in genes associated with cell cycle regulation as well as neuronal and glial properties.

Conclusion: Despite the negligible differences, which are not as evident as one would expect from cytotoxic materials, all tested vertically aligned MWCNT showed good biocompatibility profiles. Therefore, MWCNT-coated microelectrode array systems provide a promising approach to electrically stimulate remaining neural cells.