Physical and electrical characterization of TexasPEG: An electrically conductive neuronal scaffold

Abstract

Background:Graphene and its derivatives have been shown to be biocompatible and electrically active materials upon which neurons readily grow. The fusogen poly(ethylene glycol) (PEG) has been shown to improve outcomes after cervical and dorsal spinal cord transection. The long and narrow PEGylated graphene nanoribbon stacks (PEG-GNRs) with their 5 μm × 200 nm × 10 nm dimensions can provide a scaffold upon which neurons can grow and fuse. We disclose here the extensive characterization data for the PEG-GNRs.Methods:PEG-GNRs were chemically synthesized and chemically and electrically characterized.Results:The average aspect ratio of the PEG-GNRs was determined to be ~85, which corresponds to a critical percolation value (the point where insulating material becomes conductive by addition of conductive particles) of 1%. However, there was not a sharp increase in AC conductivity at frequencies relevant to action potentials.Conclusion:A robust characterization of PEG-GNRs is discussed, though the precise origin of efficacy in improving outcomes following spinal cord transection is not known.

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“…Furthermore, the determined resistance of 14 MΩ is quite reasonable, when compared to experimentally reported conductivity value (∼10 −7 S/m) for the PEG-600 liquid. 81…”

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“…It should be noted that a sharp transection typically generates <10 Newtons (N: SI unit of force) of force versus approximately 26,000 N experienced during clinical SCI, a 2600 times difference. [122] Iseda et al . [58] concluded that “ a single severance, which minimizes damage in the lesion site,…spare(s) nearby cells.…”

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“…described physical and electrical characterization of Texas PEG, the PEG fusogen combined with graphene nanoribbons (GNR) they developed. [ 25 ] By adding conductive GNR to the fusogen solution, the PEG–GNR mixture is believed to first act as an electrical conduit and then as an electrically active scaffold upon which the neurons will grow, directing their processes across the spinal cord gap. [ 20 ] Kim and his colleagues used PEG alone in their mouse experiment and PEG–GNR in their rat experiment.…”