Single graphene nanopore for biomimetic ion channel via tunably voltage-modulated ion transport

Abstract

Biological ion channels possess a remarkable ability to selectively modulate ionic flux and play an irreplaceable role in many life processes. The modulation of ion transport through nanopores or nanochannels has received considerable attention due to the similar transport mechanism of biological ionic channels. Graphene has become the most promising membrane material because of its good permeability, mechanical strength and chemical stability. Based on its excellent electrical conductivity, it is possible to apply the gate voltage on the graphene to modulate ion transport through the graphene nanopore. Herein, the graphene/polyethylene terephthalate (G/PET) composite nanochannel was prepared by swift heavy ion irradiation, and gate voltage was applied on it. The results exhibited that the transport of cations (K+, Na+, Li+, Mg2+) can be electrostatically modulated by the applied gate voltage. The G/PET nanochannel imitated the K+ ions biological nanochannel and impeded the transport of divalent ions with K+/ions selectivity up to ∼4.2. Furthermore, it was confirmed that the applied gate voltage can change the electric potential around the graphene nanopore and the surface of the graphene through simulation. Therefore, the changed potential caused the accumulation and depletion of anions and cations near the graphene nanopore and has the ability to modulate cations transport through the graphene nanopore. This work demonstrated that the graphene nanopore with applied gate voltage can effectively modulate ion transport and exhibit significant selectivity of monovalent and divalent cations.