Conical-nanotube ion-current rectifiers: the role of surface charge.
Ion channels are protein pores that span cell membranes and open and close in response to stimuli like changes in the transmembrane potential, binding of a ligand, or mechanical stress. When open, ions pass through the pore, and hence across the cell membrane, and when closed, ion-transport is precluded. Hence, these channels are nanodevices that have a current-rectification function. There is intense research effort aimed at understanding the molecular-level mechanism for this function. One approach for elucidating the mechanism is to construct a simple abiotic system that mimics this function and to use the mechanistic details of this mimic as a guide to understand the more complex biological channel. We describe here such an abiotic mimic: a synthetic membrane that contains a single conical gold nanotube. The advantage of this mimic is that the surface charge and chemistry of the nanotube wall can be varied, at will, by judicious choice of electrolyte or by thiol chemisorption. This has allowed us to make conical Au nanotubes that rectify the ion current and, just as importantly, to definitively elucidate the mechanism of this function.
Siwy
Zuzanna
Z
Department of Chemistry, Center for Research at the Bio/Nano Interface, University of Florida, Gainesville, FL 32611-7200, USA.
Heins
Elizabeth
E
Harrell
C Chad
CC
Kohli
Punit
P
Martin
Charles R
CR
D006046:Gold / Q000737:chemistry; D007473:Ion Channels / Q000737:chemistry* / Q000378:metabolism; D007700:Kinetics; D008564:Membrane Potentials; D043942:Nanotubes / Q000737:chemistry*; D015221:Potassium Channels / Q000737:chemistry; D055672:Static Electricity
D007473:Ion Channels; D015221:Potassium Channels; D006046:Gold