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Nano Lett. 2017 Feb 8;17(2):1204-1211. doi: 10.1021/acs.nanolett.6b04967. Epub 2017 Jan 19.

Single-Walled Carbon Nanotubes: Mimics of Biological Ion Channels.

Author information

1
Department of Chemistry and ‡Department of Electrical Engineering, Columbia University , New York, New York 10027, United States.

Abstract

Here we report on the ion conductance through individual, small diameter single-walled carbon nanotubes. We find that they are mimics of ion channels found in natural systems. We explore the factors governing the ion selectivity and permeation through single-walled carbon nanotubes by considering an electrostatic mechanism built around a simplified version of the Gouy-Chapman theory. We find that the single-walled carbon nanotubes preferentially transported cations and that the cation permeability is size-dependent. The ionic conductance increases as the absolute hydration enthalpy decreases for monovalent cations with similar solid-state radii, hydrated radii, and bulk mobility. Charge screening experiments using either the addition of cationic or anionic polymers, divalent metal cations, or changes in pH reveal the enormous impact of the negatively charged carboxylates at the entrance of the single-walled carbon nanotubes. These observations were modeled in the low-to-medium concentration range (0.1-2.0 M) by an electrostatic mechanism that mimics the behavior observed in many biological ion channel-forming proteins. Moreover, multi-ion conduction in the high concentration range (>2.0 M) further reinforces the similarity between single-walled carbon nanotubes and protein ion channels.

KEYWORDS:

Ion channel; multi-ion conduction; nanofluidic device; single-walled carbon nanotubes

PMID:
28103039
PMCID:
PMC5301282
DOI:
10.1021/acs.nanolett.6b04967
[Indexed for MEDLINE]
Free PMC Article

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