Reversing current rectification to improve DNA‐sensing sensitivity in conical nanopores

Abstract

Herein, we report the ultrasensitive DNA detection through designing an elegant nanopore biosensor as the first case to realize the reversal of current rectification direction for sensing. Attributed to the unique asymmetric structure, the glass conical nanopore exhibits the sensitive response to the surface charge, which can be facilely monitored by ion current rectification curves. In our design, an enzymatic cleavage reaction was employed to alter the surface charge of the nanopore for DNA sensing. The measured ion current rectification was strongly responsive to DNA concentrations, even reaching to the reversed status from the negative ratio (−6.5) to the positive ratio (+16.1). The detectable concentration for DNA was as low as 0.1 fM. This is an ultrasensitive and label‐free DNA sensing approach, based on the rectification direction‐reversed amplification in a single glass conical nanopore.

Micro- and Nanofluidic pH Sensors Based on Electrodiffusioosmosis

“…Such conditions induce an electroosmotic flow (EOF) [ 12 ] or an electrohydrodynamic (EHD) flow [ 13 ] under an externally applied electric field. Although ion selectivity is often provided using ion exchange membranes [ 14 , 15 ], ionophores [ 16 , 17 ], or glass nanopores [ 18 , 19 , 20 ], recent fabrication techniques enable us to artificially design nanoscale structures that achieve ion selectivity. Using EOF and EHD flows, the velocity control of biomacromolecules, e.g., deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) molecules, was also proposed [ 21 , 22 , 23 ].…”

“…Furthermore, chemically modified channel surfaces and their junctions were used to produce an ionic diode [ 24 , 25 ] and an ion-sensitive field-effect transistor [ 26 ]. Cai et al [ 18 ] successfully modified the surfaces of glass pipette tips to detect DNA by ICR measurements. Ma et al [ 19 ] developed an aptamer-functionalized nanopipette for the detection of N protein, which was effective for the identification of SARS-CoV-2.…”

An ultrasensitive aptasensor of SARS-CoV-2 N protein based on ion current rectification with nanopipettes

“…According to the electrochemical characterization changes caused by the change of the surface charge of the nanopipettes before and after the capture probe captures the target are observed, the qualitative and quantitative analysis of the target is realized. This type of sensor has been used to detect nucleic acids [22] , [23] , [24] , proteins [25] , [26] , [27] , enzymatic activities [28] , metal ions [29] , [30] , [31] , etc.…”

Design of Multifunctional Nanopore Using Polyampholyte Brush with Composition Gradient

“…Biological pores and channels regulate the exchange of ions and molecules between cellular compartments. The outstanding selectivity and gating efficiency of these biological passageways are desired for a wide array of applications such as biosensing, − energy conversion, − and nanofiltration. − However, the understanding of biological nanopores is not complete due to the difficulty of experimental visualization of their dynamic ultrastructure. Growing research efforts have been devoted to developing artificial nanopores, especially biomimetic ones that allow for the transformation of biological functions into more robust man-made systems that are not limited to work at physiological conditions. − Artificial systems also provide an in vitro platform to investigate the gating mechanisms of biological nanopores, by either directly implementing biological components of interest , or employing synthetic coating materials − that emulate their biological analogs.…”