Ionic current conduction at low voltage of track-etched double conical nanopores modified by surfactant CTAB
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ORIGINAL PAPER
Ionic current conduction at low voltage of track‑etched double conical nanopores modified by surfactant CTAB XiaoRui Zhu1 · Lin Wang2 · CeMing Wang3 · YuGang Wang3 Received: 5 May 2020 / Accepted: 5 October 2020 © The Polymer Society, Taipei 2020
Abstract In order to investigate the influence of surfactant on double conical nanopore fabricated with the track-etching technique, we added the cationic surfactant hexadecyl trimethylammonium bromide (CTAB) into the working electrolyte of 0.1 M KCl. By controlling the modified region and the concentration of CTAB, the ionic current conduction of the nanopore could be tuned. Results showed that, in low voltage condition (− 1 V to + 1 V), ionic current conduction of track-etched conical nanopores is mainly decided by the tip size and shape of the nanopores. Keywords Heavy ion track-etched · Single double-conical nanopore · Ionic current rectification · CTAB
Introduction Biomimetic nanopores show interesting and useful characteristics that can mimic some of the properties observed in biological ion channels, e.g., ionic current rectification and ion selectivity [1], and offer new possibilities for electrochemical sensing [2–9]. Ionic current rectification can be caused by asymmetry of the pore’s geometry and the presence of surface charges [2, 7, 10–17]. This effect has also been observed in geometrically symmetric nanopores with patterned surface charges where a junction between two zones with positive and negative surface charges exists [18–24]. In most studies, inorganic salts (e.g., KCl and NaCl) in aqueous solutions have been used to tune the ionic current rectification of nanopore. Siwy and co-workers have considered the case of ionic liquids, aprotic solvents, calcium ions and solid-state electrolytes [25–30]. Yin et al. have studied transport phenomena at the * XiaoRui Zhu [email protected] 1
Energy‑Saving Building Materials Innovative Collaboration Center of Henan Province, Xinyang Normal University, Xinyang 464000, China
2
Key Laboratory of Nuclear Radiation and Nuclear Technology, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
3
State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871, China
nanoscale using organic solvents where the electrolyte ions adsorbed on the pore surface can cause charge inversion and current rectification [31] Ali et al. presented an experimental and theoretical description of calcium binding in a single conical nanopore functionalized with pH-sensitive phosphonic acid chains [32]. Zhang et al. designed and fabricated a series of self-gating nanofluidic devices by integrating a fully closed pH oscillator with proton-gated single-/multi-nanochannels membranes [33]. Zhai et al. used multivalent cations Ce3+ and Ca2+ to mimic the possible regulation process of artificial nanochannels, found that trivalent cation can lead to a charge inversion of the inner wall of ACRN and thus change the ion transport state from c
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