Heterogeneous Nanopore Arrays - Selective Modification of Nanopores Embedded in a Membrane

Much effort in the field of nanopore research has been directed toward reproducing the efficient transport phenomena of biological ion channels. For synthetic nanopores to replicate channel function on the scale of a cellular membrane, it is necessary to consider the modes of crosstalk between channels as well as to develop approaches to prepare nanopore arrays consisting of pores with different transport properties, akin to a membrane in an axon. In this manuscript, first ion concentration polarization (ICP) is identified as the primary means of the crosstalk, and subsequently, the extent and degree of ICP is tuned via targeted chemical modification of the pore walls' functional groups. Next, two fabrication methods of a model two-nanopore array are presented in a silicon nitride membrane in which one nanopore contains a bipolar ionic junction and functions as an ionic diode, while the other one is a homogeneously charged ionic resistor. The targeted chemical modification of a thin gold layer at the opening of one pore in an array that leaves the other pore located a few tens of nm away, unmodified, is utilized. These results provide an important framework for designing abiotic ionic circuits that can mimic physiological multichannel ion transport and communication.