Specific adsorption of trivalent cations in biological nanopores determines conductance dynamics and reverses ionic selectivity

Queralt-Martín, María; Perini, Deborah Aurora; Alcaraz, Antonio

doi:10.1039/d0cp04486e

Cited by 6 publications

(4 citation statements)

References 76 publications

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“…These data (<SI>) were plotted as a function of the measured current (Figure S1C) to obtain the so-called parabolic coefficient SG/G 2 from fitting the equation <SI> = (SG/G 2 )I 2 . Note that in the case of PI NP, noise analysis is limited to V > 0 because for V < 0 the system shows limiting current involving non-equilibrium features 38,39 .…”

Section: Current Fluctuation Analysismentioning

confidence: 99%

Biphasic concentration patterns in ionic transport under nanoconfinement revealed in steady-state and time-dependent properties

Queralt-Martín

Perez-Grau

Alvero-González

et al. 2023

The Journal of Chemical Physics

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Ion permeation across nanoscopic structures differs considerably from microfluidics because of strong steric constraints, transformed solvent properties and charge-regulation effects revealed mostly in diluted solutions. However, little is known about nanofluidics in moderately concentrated solutions, which are critically important for industrial applications and living systems. Here we show that nanoconfinement triggers general biphasic concentration patterns in a myriad of ion transport properties using two contrasting systems: a biological ion channel and a much larger synthetic nanopore. Our findings show a low concentration regime ruled by classical Debye screening and another one where ion-ion correlations and enhanced ion-surface interactions contribute differently to each electrophysiological property. Thus, different quantities (e.g., conductance vs noise) measured under the same conditions may appear contradictory because they belong to different concentration regimes. In addition, non-linear effects that are barely visible in bulk conductivity only in extremely concentrated solutions become apparent in nanochannels around physiological conditions.

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Section: Current Fluctuation Analysismentioning

confidence: 99%

Biphasic concentration patterns in ionic transport under nanoconfinement revealed in steady-state and time-dependent properties

Queralt-Martín

Perez-Grau

Alvero-González

et al. 2023

The Journal of Chemical Physics

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“…13 The ion transport phenomena in nanochannels are related to the electrostatic effect of surface charges on the wall. 14 Generally, negatively charged surfaces (usually found in silicon-based channels) attract counter cations. In a fluidic channel of size much larger than the Debye length, the electrostatic potential at the wall causes negligible influence on the ion transport due to the screening by ions.…”

Section: ■ Introductionmentioning

confidence: 99%

“…The ion transport phenomena in nanochannels are related to the electrostatic effect of surface charges on the wall . Generally, negatively charged surfaces (usually found in silicon-based channels) attract counter cations.…”

Section: Introductionmentioning

confidence: 99%

Regulating Nonlinear Ion Transport through a Solid-State Pore by Partial Surface Coatings

Leong

Tsutsui

Yokota

et al. 2023

ACS Appl. Mater. Interfaces

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Using functional nanofluidic devices to manipulate ion transport allows us to explore the nanoscale development of blue energy harvesters and iontronic building blocks. Herein, we report on a method to alter the nonlinear ionic current through a pore by partial dielectric coatings. A variety of dielectric materials are examined on both the inner and outer surfaces of the channel with four different patterns of coated or uncoated surfaces. Through controlling the specific part of the surface charge, the pore can behave like a resistor, diode, and bipolar junction transistor. We use numerical simulations to find out the reason for the asymmetric ion transport in the pore and illustrate the relationship between specifically charged surfaces and electroosmotic flow. These findings help understand the role of the corresponding surface composition in ion transport, which provides a direct approach to modify the electroosmotic-flow-driven ionic current rectification in the channel-based device via dielectric coatings.

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“…1(a)], the charge fluctuations within the cytoplasm are the result of two coupled noisy processes. First, the ionic current through the ion channels is noisy [15], with the ensuing fluctuations in intracellular ion concentrations causing voltage noise in V mem . Second, any noise originating in V mem , e.g., due to a random depolarization of a membrane patch or even thermal noise [16,17], will * Electronic mail: ekinci@bu.edu cause fluctuations in the transmembrane current [18] and hence the intracellular ion concentrations.…”

Section: Introductionmentioning

confidence: 99%

Measurement of the Low-Frequency Charge Noise of Bacteria

Yang,

Gress,

Ekinci

2022

Preprint

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Bacteria meticulously regulate their intracellular ion concentrations and create ionic concentration gradients across the bacterial membrane. These ionic concentration gradients provide free energy for many cellular processes and are maintained by transmembrane transport. Given the physical dimensions of a bacterium and the stochasticity in transmembrane transport, intracellular ion concentrations and hence the charge state of a bacterium are bound to fluctuate. Here, we investigate the charge noise of 100s of non-motile bacteria by combining electrical measurement techniques from condensed matter physics with microfluidics. In our experiments, bacteria in a microchannel generate charge density fluctuations in the embedding electrolyte due to random influx and efflux of ions. Detected as electrical resistance noise, these charge density fluctuations display a power spectral density proportional to 1/f 2 for frequencies 0.05 Hz ≤ f ≤ 1 Hz. Fits to a simple noise model suggest that the steady-state charge of a bacterium fluctuates by ±1.30 × 10 6 e (e ≈ 1.60 × 10 −19 C), indicating that bacterial ion homeostasis is highly dynamic and dominated by strong charge noise. The rms charge noise can then be used to estimate the fluctuations in the membrane potential; however, the estimates are unreliable due to our limited understanding of the intracellular concentration gradients.

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Specific adsorption of trivalent cations in biological nanopores determines conductance dynamics and reverses ionic selectivity

Abstract: We show that the interaction of trivalent electrolytes with biological nanopores occurs via ion-specific adsorption yielding differential modulation of ion conduction and selectivity inversion.

Cited by 6 publications

References 76 publications

Biphasic concentration patterns in ionic transport under nanoconfinement revealed in steady-state and time-dependent properties

Biphasic concentration patterns in ionic transport under nanoconfinement revealed in steady-state and time-dependent properties

Regulating Nonlinear Ion Transport through a Solid-State Pore by Partial Surface Coatings

Measurement of the Low-Frequency Charge Noise of Bacteria

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