  Reproducing the exquisite ion selectivity displayed by biological ion
channels in artificial nanopore systems has proven to be one of the most
challenging tasks undertaken by the nanopore community, yet a successful
achievement of this goal offers immense technological potential. Here we show a
strategy to design solid-state nanopores that selectively transport potassium
ions and show negligible conductance for sodium ions. The nanopores contain
walls decorated with 4'-aminobenzo-18-crown-6 ether and ssDNA molecules located
at one pore entrance. The ionic selectivity stems from facilitated transport of
potassium ions in the pore region containing crown ethers, while the highly
charged ssDNA plays the role of a cation filter. Achieving potassium
selectivity in solid-state nanopores opens new avenues toward advanced
separation processes, more efficient biosensing technologies and novel
biomimetic nanopore systems.
