Nanopore Electrochemistry: A Nexus for Molecular Control of Electron Transfer Reactions

Abstract

Pore-based structures occur widely in living organisms. Ion channels embedded in cell membranes, for example, provide pathways, where electron and proton transfer are coupled to the exchange of vital molecules. Learning from mother nature, a recent surge in activity has focused on artificial nanopore architectures to effect electrochemical transformations not accessible in larger structures. Here, we highlight these exciting advances. Starting with a brief overview of nanopore electrodes, including the early history and development of nanopore sensing based on nanopore-confined electrochemistry, we address the core concepts and special characteristics of nanopores in electron transfer. We describe nanopore-based electrochemical sensing and processing, discuss performance limits and challenges, and conclude with an outlook for next-generation nanopore electrode sensing platforms and the opportunities they present.

The Effects of Tetramethylammonium Cation on Oligonucleotide Analysis with Aerolysin Nanopore

“…Due to the occupation of oligonucleotides in nanopore, the blockade currents induced by Poly(dA) 3 , Poly (dA) 4 and Poly(dA) 5 is related to the length of oligonucleotides. Significantly, the blockade currents of Poly(dA) 5 are very closed to 0 pA in TMAÀ Cl system, much more complete than in KCl system. Blockage events of oligonucleotides in KCl and TMAÀ Cl system are analysed by I/I 0 and blockade duration.…”

“…In addition, the capture rate of oligonucleotides is distinctly increased, and it is speculated that amphipathic TMA + can enhance the affinity of aerolysin nanopore for oligonucleotides. Furthermore, the estimated effective charges (Z inside ) of oligonucleotides inside aerolysin nanopore in two solutions suggest that the screening of K + on Poly(dA) 3 , Poly(dA) 4 , and Poly(dA) 5 is more effective than that for TMA + . This report deepens our understanding of the effects of cations in electrolyte.…”

“…Experimental results demonstrate that the blockage of oligonucleotides in the TMA + system is distinctly more considerable than that in K + system. In particular, the blockade currents of Poly(dA) 5 are very closed to 0 pA. In addition, the capture rate of oligonucleotides is distinctly increased, and it is speculated that amphipathic TMA + can enhance the affinity of aerolysin nanopore for oligonucleotides.…”

“…[1][2][3][4] The modulation of ionic current inside nanopore contains abundant information about target molecules, including its conformation, composition and dynamic process. [5][6][7] The tunnel current by analyst is extremely sensitive and can discriminate the minor differences. According to this principle, single-strand DNA could be sequenced as each base sequentially traverses nanopore.…”

“…[19] Subsequently, it was used to detect various molecules, including oligosaccharides, [20] peptides, [21] proteins [22][23][24] and poly (ethylene glycols) (PEGs). [25] Since the diameter of aerolysin nanopore precisely allows for the passage of single-stranded DNA, aerolysin nanopore was demonstrated that could discriminate oligonucleotides of different lengths directly and real-time monitor the stepwise cleavage of Poly(dA) 5 by Exonuclease I. [6] However, to meet the increasing demand of high sensitivity, the commonly used system need to be dramatically improved.…”