Abstract
Nanochannels with functional elements have shown promise for DNA sequencing, single-molecule sensing, and ion gating. Ionic current measurement is currently a benchmark, but is focused solely on the contribution from nanochannels’ inner-wall functional elements (NIWFE); the attributes of functional elements at nanochannels’ outer surface (NOSFE) are nearly ignored, and remain elusive. Here we show that the role of NOSFE and NIWFE for ion gating can be distinguished by constructing DNA architectures using dual-current readout. The established molecular switches have continuously tunable and reversible ion-gating ability. We find that NOSFE exhibits negligible ion-gating behavior, but it can produce a synergistic effect in alliance with NIWFE. Moreover, the high-efficiency gating systems display more noticeable synergistic effect than the low-efficiency ones. We also reveal that the probe amount of NOSFE and NIWFE is almost equally distributed in our biomimetic nanochannels, which is potentially a premise for the synergistic ion-gating phenomena.
Highlights
A critical question arises: what role do regional functional elements play in ion gating? Inability to clarify this issue has long been a barrier to understanding the delicate function of biomimetic nanochannels
To systematically study regional ion-gating function of biomimetic nanochannels, we investigate a low-efficiency iongating system composed of DNA traditional sandwich (DNA TS) and a high-efficiency ion-gating system created from DNA superstructure (DNA SS), both labeled with double-methylene blue (MB) electroactive tags (Supplementary Fig. 2)
The assembled DNA frameworks act as molecular switch mediating electron transfer (ET) to generate electrolytic current (EC) signal, as well as guide transmembrane ions transport (IT) to produce ionic current (IC) signal, both of which are monitored by a home-made dualcurrent electrochemical setup (Fig. 1c)
Summary
Inability to clarify this issue has long been a barrier to understanding the delicate function of biomimetic nanochannels This is a problem in nanochannel-based DNA sequencing[22,23,24,25,26,27,28,29] and single-molecule sensing[30,31,32,33,34,35,36]. Detection of individual DNA abasic sites[37], investigation of single-molecule stereochemistry reaction[38], and probing single-molecule enzyme kinetics[31] have been realized in this manner This sensing strategy may be improved provided that NOSFE is taken into account, since it can prescreen a target molecule at the nanochannel outer surface rather than rely solely on the NIWFE, which shall enhance sensing-specificity and flexibility. The gating efficiency is experimentally elucidated with integrated dual-current signals, which offer a technical means to probing of ion-gating behaviors of biomimetic nanochannels
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