Electrical trapping mechanism of single-microparticles in a pore sensor

Akihide Arima,Yuhui He,Sou Ryuzaki,Makusu Tsutsui,Masateru Taniguchi

doi:10.1063/1.4967214

Akihide Arima, Yuhui He + Show 3 more

Open Access

https://doi.org/10.1063/1.4967214

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Abstract

Nanopore sensing via resistive pulse technique are utilized as a potent tool to characterize physical and chemical property of single –molecules and –particles. In this article, we studied the influence of particle trajectory to the ionic conductance through a pore. We performed the optical/electrical simultaneous sensing of electrophoretic capture dynamics of single-particles at a pore using a microchannel/nanopore system. We detected ionic current drops synchronous to a fluorescently dyed particle being electrophoretically drawn and become immobilized at a pore in the optical imaging. We also identified anomalous trapping events wherein particles were captured at nanoscale pin-holes formed unintentionally in a SiN membrane that gave rise to relatively small current drops. This method is expected to be a useful platform for testing novel nanopore sensor design wherein current behaves in unpredictable manner.

Highlights

The Coulter counter technique is a powerful tool especially in the field of biological and particulate analysis.[1,2,3,4,5,6] The principal is based on electrical detections of ion exclusion effects inside a conduit when a particle blocks ion transport during translocation.[7,8] Through the measurement, we can acquire information concerning volume of the particle from the amplitudes of the ionic current signals as larger analytes exclude more ions
On the other hand, combining optical microscopy observations with nanopore measurements have proven to be an effective technique to address this issue: fast translocation of dyed particles or molecules through a fluidic channel are traced by fluorescence imaging while recording the cross-pore ionic current simultaneously so that the ionic current signals obtained can be assigned unambiguously to the actual events occurred.[22,23,24,25,26,27]
The amplitude of the current drop was quite small for the second trap. This again suggests that the pore orifice has already been largely occupied by the first particle so that the subsequent trapping could not block the ion passage further. This simultaneous measurement reveals the origin of multiple-stage current drop is not the stepwise shift of particle position occurred by a single particle but multiple trapping

Summary

INTRODUCTION

The Coulter counter technique is a powerful tool especially in the field of biological and particulate analysis.[1,2,3,4,5,6] The principal is based on electrical detections of ion exclusion effects inside a conduit when a particle blocks ion transport during translocation.[7,8] Through the measurement, we can acquire information concerning volume of the particle from the amplitudes of the ionic current signals as larger analytes exclude more ions. On the other hand, combining optical microscopy observations with nanopore measurements have proven to be an effective technique to address this issue: fast translocation of dyed particles or molecules through a fluidic channel are traced by fluorescence imaging while recording the cross-pore ionic current simultaneously so that the ionic current signals obtained can be assigned unambiguously to the actual events occurred.[22,23,24,25,26,27] Mitsui et al.[22] studied electrophoretic capture of single-molecule DNA into a nanopore by fluorescent observations alone They observed motion of DNA around a nanopore with different gate voltages and presented the possibility for controlling the trajectory of analyte at the vicinity of a nanopore. By recording temporal changes in the ionic current and optical images, we show the detailed mechanism of the nanopore trapping

EXPERIMENTAL

Single-particle detections using nanopore trapping method

RESULTS AND DISCUSSION

CONCLUSION