Ionic Conductance of 1.5 nm Diameter Carbon Nanotube Porins*

Controlling ion transport on a molecular scale is important for applications ranging from industrial water treatment, to membrane separations, to bioelectronic interface design. Carbon nanotube porins—pore channels formed by ultra-short carbon nanotubes assembled in a lipid membrane—exploit nanoscale confinement and unique structure of carbon nanotube walls to transport water, protons, and small ions with efficiency that rivals and sometimes exceeds that of biological channels. We report the ion conductance characteristics and ion selectivity of the individual 1.5 nm dimeter carbon nanotube porins. The conductance follows the power law scaling that is distinct from the previously reported characteristics of carbon nanotubes. We will also discuss the physical mechanisms that lead to these conductance characteristics. Overall, carbon nanotube porins represent versatile biomimetic membrane pores that are ideal for studying nanoscale transport phenomena and building new separation technologies and bioelectronic interfaces.