Electroanalytical Opportunities Derived from Ion Transfer at Interfaces between Immiscible Electrolyte Solutions

Ionic current rectification (ICR) phenomena within dual glass pipettes are investigated for the first time. We demonstrate that the ionic flow presents different behaviors in dual nano- and micropipettes when the two channels are filled with the same electrolyte KCl and hung in air. Bare dual nanopipettes cannot rectify the ionic current because of their geometric symmetry, but the ICR can be directly observed based on bare dual micropipettes. The phenomena based on dual micropipettes could be explained by the simulation of the Poisson-Nernst-Plank equation. After modification with different approaches, the dual nanopipettes have asymmetric charge patterns and show various ICR behaviors. They have been successfully employed to fabricate various nanodevices, such as ionic diodes and bipolar junction transistors. Due to the simple and fast fabrication with high reproducibility, these dual pipettes can provide a novel platform for controlling ionic flow in nano- and microfluidics, fabrication of novel nanodevices, and detection of biomolecules.

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confidence: 99%

Ionic Current Behaviors of Dual Nano- and Micropipettes

Zhang

Yin

et al. 2018

“…The inconformity of the complex ratio between water and organic phases for G1 and G2 indicates a deprotonation process at the W/DCE interface to some extent. As shown in Scheme , extra protons may separate from the dendrimer when transferring across the interface, which is similar to the change of the protein structure at the organogel surface. , …”

Section: Resultsmentioning

confidence: 90%

Investigation of Dendrimer Transfer Behaviors at the Micro-Water/1,2-Dichloroethane Interface Facilitated by Dibenzo-18-Crown-6

et al. 2020

Trans-interfacial behaviors of multiple ionic species at the interface between two immiscible electrolyte solutions (ITIES) are of importance to biomembrane mimicking, chemical and biosensing, and interfacial molecular catalysis. Utilizing host–guest interaction to facilitate ion transfer is an effective and commonly used method to decrease the Gibbs energy of transfer of a target molecule. Herein, we investigated a facilitated ion transfer (FIT) process of poly(amidoamine)dendrimer (PAMAM, G0–G2) by dibenzo-18-crown-6 (DB18C6) at the microinterfaces between water and 1,2-dichloroethane (μ-W/DCE). Because of the host–guest interaction between a dendrimer and a ligand, negative shifts of the transfer potentials were observed using cyclic voltammetry or Osteryoung square wave voltammetry. From the FIT behavior of the dendrimer, we revealed that each DB18C6 could selectively coordinate with one amino group. We first evaluated the protonated status of the intermediate state (1:2) exactly under the conditions the dendrimer (G1) transfers across the interface using the electrochemical mass spectrometry (EC-MS)-hyphenated technique, which is much smaller than the protonated status in the water phase (1:8 to 14). Using the same methodology, we also studied the facilitated transfer behaviors of G0 and G2. Based on these results, we put forward the mechanism of the FIT process, which might involve a deprotonating process at the interface for higher-generation dendrimers.

“…The primary electrochemical techniques used to date to generate the electroanalytical signal at the ITIES in the presence of redox-inactive ions are amperometry [46][47][48][49][50][51][52] and voltammetry (cyclic voltammetry (CV) 8,16,28,[53][54][55] and differential pulse voltammetry (DPV), 21,40,56,57 respectively). Successful application of these methods to achieve precise quantitative analysis at the macroITIES can be hampered by the presence of interfering capacitive currents, background currents due to residual ion transfer of the aqueous electrolyte across the full polarisable potential window (PPW), and the inherently high resistance of a liquid|liquid (L|L) electrochemical cell due to the presence of an organic phase.…”

Section: Introductionmentioning

confidence: 99%

“…Examples of redox-inactive ions quantitatively detected by their reversible ion transfer across the ITIES include drugs, such as cocaine, propranolol, − metoprolol, daunorubicin, topotecan, antimicrobial drug ions (quinolones and sulfonamides) and fluoroquinolone antibiotics, neurotransmitters and neuromodulators such as dopamine, − acetylcholine, − tryptamine, serotonin, and gamma-aminobutyric acid, pathogenic bacterial quorum sensing molecules such as 4-hydroxy-2-heptylquinoline (HHQ) and 2-heptyl-3,4-dihydroxyquinoline (pseudomonas quinolone signal, PQS), and heavy-metal-ions such as Pb(II), , Cd(II) ,− and Cr(VI). , Comprehensive overviews of recent developments in this fast-evolving field can be found in reviews by Arrigan, − Dassie, Herzog, Lee, Shen, and their co-workers.…”

mentioning

confidence: 99%

“…The primary electrochemical techniques used to date to generate the electroanalytical signal at the ITIES in the presence of redox-inactive ions are amperometry − and voltammetry [cyclic voltammetry (CV) ,,,− and differential pulse voltammetry (DPV)]. ,,, Successful application of these methods to achieve precise quantitative analysis at the macroITIES can be hampered by the presence of interfering capacitive currents, background currents due to residual ion transfer of the aqueous electrolyte across the full polarizable potential window (PPW), and the inherently high resistance of a liquid|liquid (L|L) electrochemical cell, because of the presence of an organic phase. , The most successful approach to date to overcome these limitations, achieving in some cases subnanomolar quantification of organic or inorganic ions, is the combination of interfacial miniaturization to the microscale or nanoscale and differential pulse stripping voltammetry (DPSV). ,,− …”

mentioning

confidence: 99%

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Quantitative Analysis of Redox-Inactive Ions by AC Voltammetry at a Polarized Interface between Two Immiscible Electrolyte Solutions

Suárez-Herrera

Scanlon

2020

The interface between two immiscible electrolyte solutions (ITIES) is ideally suited to detect redox-inactive ions by their ion transfer. Such electroanalysis, based on the Nernst-Donnan equation, has been predominantly carried out by amperometry, cyclic or differential pulse voltammetry. Here, we introduce a new electroanalytical method based on AC voltammetry with inherent advantages over traditional approaches such as avoidance of positive feedback iR compensation, a major issue for liquid|liquid electrochemical cells containing resistive organic media and interfacial areas in the cm 2 and mm 2 range. A theoretical background outlining the generation of the analytical signal is provided and based on extracting the component that depends on the Warburg impedance from the total impedance. The quantitative detection of a series of model redox-inactive tetraalkylammonium cations is demonstrated, with evidence provided of the transient adsorption of these cations at the interface during the course of ion transfer. As ion transfer is diffusion limited, by changing the voltage excitation frequency during AC voltammetry, the intensity of the Faradaic response can be enhanced at low frequencies (1 Hz) or made to disappear completely at higher frequencies (99 Hz). The latter produces an AC voltammogram equivalent to a "blank" measurement in the absence of analyte and is ideal for background subtraction. Major opportunities therefore exist for the sensitive detection of ionic analyte when a "blank" measurement in the absence of analyte is impossible. This approach is particularly useful to deconvolute signals related to reversible 2 electrochemical reactions from those due to irreversible processes, which do not give AC signals.