Photogating of ionic currents across the lipid bilayer

Drain, Charles Michael; Christensen, B.; Mauzerall, D.

doi:10.1109/iembs.1989.96225

Cited by 9 publications

(13 citation statements)

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“…2 A shows the photogenerated increase of the voltagedriven current carried by borate anions after a 1-,us pulsed illumination to the symmetrical acceptor/sensitizer/acceptor system, and the striking increases with small structural changes in the borates. The increase in the current is the photogating effect named earlier (Drain et al, 1989;Mauzerall and Drain, 1992). It arises from the photoformation of P+ by electron transfer from the excited porphyrin in the bilayer to the ionic acceptor across the membrane-solution interface.…”

Section: Photogating Currents Driven By Applied Voltagementioning

confidence: 99%

“…T (OC) Id (nA) I,, (nA) t12 ( P+ cations is the photogating current studied in the symmetric system with electron acceptors on both sides (Drain et al, 1989;Drain and Mauzerall, 1992; Mauzerall and Drain, 1992). When a saturating concentration of electron donor is added, the changes of the photogating current are shown by curves a versus b and d versus c in Fig.…”

Section: Temperature Dependencementioning

confidence: 99%

“…In most of the published studies attention has been paid to the electrostatic properties and the ion behavior at membrane-water interfaces (McLaughlin, 1977(McLaughlin, , 1989Huber and Ramberg, 1981;Cevc, 1990) and to the translocation and distribution of a single kind of ion in the bilayer (Andersen and Fuchs, 1975;Benz et al, 1976;Lauger et al, 1981). In contrast, there are few studies (Liberman and Topaly, 1969;Drain et al, 1989;Drain and Mauzerall, 1992; Mauzerall and Drain, 1992) on the ion interactions, cooperative translocation, and related electrostatics of different kinds of ions inside the lipid membrane because of a lack of efficient probing methods. Hydrophobic ions in lipid bilayers have been used to study fundamentals of transmembrane charge transport to avoid the ion complexing steps of ion carriers (Lauger et al, 1981).…”

Section: Introductionmentioning

confidence: 99%

“…They explained such a phenomenon simply as the increased binding constant of the cation in the anion-loaded bilayer. More recent studies (Drain et al, 1989;Drain and Mauzerall, 1992;Mauzerall and Drain, 1992) have shown that the conductivity of lipophilic ions across lipid bilayers can be dramatically controlled or gated by formation of oppositely charged ions inside the bilayer. The photoformation of the cation of magnesium octaethylporphyrin (MgOEP) in the bilayer can increase the transmembrane ionic current carried by tetraphenylborate (TPhB -) anions -lOfold.…”

Section: Introductionmentioning

confidence: 99%

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Evidence for ion chain mechanism of the nonlinear charge transport of hydrophobic ions across lipid bilayers

Sun

Mauzerall

1996

Biophysical Journal

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The conductivity across a lipid bilayer by tetraphenylborate anion is increased 10-fold on the photoformation of lipophilic porphyrin cations. The cations alone have negligible conductivity. This nonlinear photogenerated increase of ion conductivity is termed the photogating effect. Substitution of H by Cl in the para position of tetraphenylborate leads to a 100-fold enhancement of conductivity, whereas the dark conductivities for this and other substituted borates are the same. Moreover, the halo-substituted borates show a large enhancement of conductivity in the low concentration range (10(-8) M), whereas that of tetraphenylborate is small and space charge is negligible. The enhanced ion conductivity has great structural sensitivity to the structure of the anion, the cation, and the lipid, whereas the partition coefficient of all the borates and the concentration of photoformed cations are only slightly affected. The photogated ion transport has a twofold larger activation energy than transport in the dark. Time-resolved photocurrents and voltages demonstrate that the translocation rate of the porphyrin cation is also enhanced 100-fold by the Cl-borate anion but only 10-fold by the H-borate anion. For these reasons the nonlinear gating effect cannot be explained by electrostatics alone, but requires an ion chain or ion aggregate mechanism. Kinetic modeling of the photoinduced current with a mixed cation-anion ion chain can fit the data well. The photogating effect allows the direct study of ion interactions within the bilayer.

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Section: Photogating Currents Driven By Applied Voltagementioning

confidence: 99%

Section: Temperature Dependencementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Evidence for ion chain mechanism of the nonlinear charge transport of hydrophobic ions across lipid bilayers

Sun

Mauzerall

1996

Biophysical Journal

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“…The electrostatic potentials of membranes have been investigated in some detail and the limitations on the use of the Gouy-Chapman-Stern theory are becoming welldefined. The theory cannot be used when the fixed charges are buried within the low dielectric interior of the membrane (McLaughlin, 1977;Andersen et al, 1978;Drain et al, 1989), or when the fixed charges are a significant distance from the surface (Langner et al, 1988). However, in the latter case the Poisson-Boltzmann equation can be used, and a simple extension of the Gouy-Chapman theory for a layer of fixed charges located some distance from the membrane ) provides a good description of the potential profile.…”

Section: Biological Importancementioning

confidence: 99%

Electrostatics of phosphoinositide bilayer membranes. Theoretical and experimental results

Langner

Cafiso

Marčelja

et al. 1990

Biophysical Journal

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We made fluorescence, electron paramagnetic resonance (EPR), electrophoretic mobility, and ionizing electrode measurements to study the effect of the monovalent lipid phosphatidylinositol (PI) and the trivalent lipid phosphatidylinositol 4,5-bisphosphate (PIP2) on the electrostatic potential adjacent to bilayer membranes. When the membranes were formed from mixtures of PI and the zwitterionic lipid phosphatidylcholine (PC), the Gouy-Chapman-Stern (GCS) theory described adequately the dependence of potential on distance (0, 1, 2 nm) from the membrane, mole % negative lipid, and [KCI]. Furthermore, all EPR and fluorescence probes reported identical surface potentials with a PC/PI membrane. With PC/PIP2 membranes, however, the anionic (coion) probes reported less negative potentials than the cationic (counterion) probes; the deviations from the GCS theory were greater for the coions than the counterions. Discreteness-of-charge theories based on the Poisson-Boltzmann equation incorrectly predict that deviations from the GCS theory should be greater for counterions than for coions. We discuss a consistent statistical mechanical theory that takes into account three effects ignored in the GCS theory: the finite size of the ions in the double layer, the electrical interaction between pairs of ions (correlation effects), and the mobile discrete nature of the surface charges. This theory correctly predicts that deviations from GCS theory should be negligible for monovalent lipids, significant for trivalent lipids, and greater for coions than for counterions.

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Design strategies for two‐dimensional material photodetectors to enhance device performance

Wang

Han

Chen

et al. 2019

InfoMat

201

143

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Two‐dimensional (2D) materials are intensively attractive for fabricating high sensitive photodetectors in terms of atomically thin flexible and ultrafast charge transport feature. Due to their atomically thin body, designing high performance detector requires new physical mechanisms and device structures. In this review, we classify design strategies and device structures into four categories depending on their physical mechanisms (photovoltaic effect, photoconductive effect, photothermoelectric effect or photobolometric effect, and surface plasma‐ wave‐assisted effect), and summarize the device performances. Finally, future prospects and development direction for 2D material photodetectors are described. Those design strategies descriptions about photoelectronic detector provide a reference for high responsivity and fast response speed photodetector at broadband sensing in the future.

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Photogating of ionic currents across the lipid bilayer

Abstract: The ionic currents of positive and negative hydrophobic ions across a -7 n,m thick lipid bilayer can be gated by the photoformation of metalloporphyrin cations in the ester region of 1336--1EEE ENGINEERING IN MEDICINE L BIOLOGY SOCIETY llTH ANNUAL INTERNATIONAL CONFERENCE

Cited by 9 publications

References 0 publications

Evidence for ion chain mechanism of the nonlinear charge transport of hydrophobic ions across lipid bilayers

Evidence for ion chain mechanism of the nonlinear charge transport of hydrophobic ions across lipid bilayers

Electrostatics of phosphoinositide bilayer membranes. Theoretical and experimental results

Design strategies for two‐dimensional material photodetectors to enhance device performance

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