Carbon nanotube as a gramicidin analogue

► (9, 9) Exohydrogenated carbon nanotube broadly mimics characteristics of gramicidin. ► Selective to monovalent cations, binds divalent cations and rejects anions. ► Conducts potassium six times faster than gramicidin. ► Potassium current reduced by 85% due to calcium ions binding at nanotube entrances. ► Two potassium ions normally occupy tube, conduction occurs when third ion enters.