Engineering small-ion transporter channels
Very fast ion channels are created between graphene two-dimensional (2D) sheets and the voltage-gating operation for an ionic transistor.
Abstract
Voltage-gated channels microfabricated in graphene sheets act as ion-selective transistors Protein channels that span lipid membranes are the primary regulators for the transport of chemical species into and out of cells. These gates and channels enable precise chemical selectivity and markedly enhanced transport speed (1, 2). Both selectivity and transport speed far exceed those of engineered membranes based on simplistic sieving and crude surface functionalization. The replication of protein-channel performance is especially challenging for mimicking potassium ion (K+) channels with their coupled activation and selectivity gates (3). These channels can pump against a concentration gradient and have a 1000:1 selectivity between K+ and sodium (Na+) ions, despite only a ∼0.38 Å difference in atomic radii. On page 501 of this issue, Xue et al. (4) created very fast ion channels between graphene two-dimensional (2D) sheets and the voltage-gating operation for an ionic transistor. Conventional microfabrication patterning and etching techniques produced lateral flow channels ∼5 µm long through a stack of ∼55 graphene layers.