Electrostatic Potentials of Bilayer Lipid Membranes: Basic Principles and Analytical Applications

Sokolov, V.S.; Mirsky, Vladimir M.

doi:10.1007/978-3-662-05204-4_11

Cited by 18 publications

(18 citation statements)

References 109 publications

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“…Dependences of ζ-potentials on the concentration of the porphyrins are shown in Figure 2. The values of ζ-potentials were equal or slightly lower than the ∆ϕ b values, indicating the absence or shallow insertion of the charged groups of the porphyrin molecules into the lipid membrane [34,35]. The same behavior was observed earlier for the negatively charged porphyrins [19].…”

Section: Adsorption On the Membranesupporting

confidence: 76%

“…The first one, the inner field compensation (IFC) method, is based on the measurement of the second harmonics of the capacitive current ( [31]). In the second method, the change of ∆ϕ b is determined from the change of the BLM conductance induced by ionophore nonactin as [32][33][34][35]…”

Section: Experiments At Blmmentioning

confidence: 99%

“…Due to penetration, organic cations are present on both sides of the membrane, thus decreasing the ∆ϕ b measured by the IFC method. Such penetration becomes weaker at low pH, where the fraction of the neutral forms of the molecules is lower [34,35,37]. This mechanism can be tested by comparison of the ∆ϕ b measured by the IFC method with that determined by measuring the membrane conductance induced by nonactin.…”

Section: Effect Of Ph On the Adsorption And Photodynamic Efficiencymentioning

confidence: 99%

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Lipid Membrane Adsorption Determines Photodynamic Efficiency of β-Imidazolyl-Substituted Porphyrins

et al. 2019

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Photosensitizers (PSs) represent a group of molecules capable of generating reactive oxygen species (ROS), such as singlet oxygen (SO); thus, they are considered to be promising agents for anti-cancer therapy. The enhancement of the photodynamic efficiency of these compounds requires increasing the PS activity in the cancer cell milieu and exactly at the target cells. In the present work, we report the synthesis, lipid membrane binding and photodynamic activity of three novel cationic PSs based on β-imidazolyl-substituted porphyrin and its Zn(II) and In(III) complexes (1H2, 1Zn and 1In). Comparison of the behavior of the investigated porphyrins at the bilayer lipid membrane (BLM) demonstrated the highest adsorption for the 1In complex and the lowest one for 1Zn. The photodynamic efficiency of these porphyrins was evaluated by determining the oxidation rate of the styryl dye, di-4-ANEPPS, incorporated into the lipid membrane. These rates were proportional to the surface density (SD) of the porphyrin molecules at the BLM and were roughly the same for all three porphyrins. This indicates that the adsorption of these porphyrins at the BLM determines their photodynamic efficiency rather than the extinction or quantum yield of singlet oxygen.

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Section: Adsorption On the Membranesupporting

confidence: 76%

Section: Experiments At Blmmentioning

confidence: 99%

Section: Effect Of Ph On the Adsorption And Photodynamic Efficiencymentioning

confidence: 99%

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Lipid Membrane Adsorption Determines Photodynamic Efficiency of β-Imidazolyl-Substituted Porphyrins

et al. 2019

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“…The membrane behaves as an elastic capacitor, thinning in response to electrostatic stresses [41,42]. The applied voltage generates a compressive stress across the membrane as a function of the applied voltage V.…”

Section: Droplet Interface Bilayer Response To Applied Voltagementioning

confidence: 99%

A new approach for investigating the response of lipid membranes to electrocompression by coupling droplet mechanics and membrane biophysics

El-Beyrouthy

Makhoul-Mansour

Taylor

et al. 2019

J. R. Soc. Interface.

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A new method for quantifying lipid–lipid interactions within biomimetic membranes undergoing electrocompression is demonstrated by coupling droplet mechanics and membrane biophysics. The membrane properties are varied by altering the lipid packing through the introduction of cholesterol. Pendant drop tensiometry is used to measure the lipid monolayer tension at an oil–water interface. Next, two lipid-coated aqueous droplets are manipulated into contact to form a bilayer membrane at their adhered interface. The droplet geometries are captured from two angles to provide accurate measurements of both the membrane area and the contact angle between the adhered droplets. Combining the monolayer tension and contact angle measurements enables estimations of the membrane tension with respect to lipid composition. Then, the membrane is electromechanically compressed using a transmembrane voltage. Electrostatic pressure, membrane tension and the work necessary for bilayer thinning are tracked, and a model is proposed to capture the mechanics of membrane compression. The results highlight that a previously unaccounted for energetic term is produced during compression, potentially reflecting changes in the lateral membrane structure. This residual energy is eliminated in cases with cholesterol mole fractions of 0.2 and higher, suggesting that cholesterol diminishes these adjustments.

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“…D4 b was measured by the intramembrane field compensation method using the second harmonic of the capacitive current (19, see also reviews 20,21). The method exploits the nonmonotonic voltage dependence of membrane capacitance (22).…”

Section: Methodsmentioning

confidence: 99%

Membrane Transport of Singlet Oxygen Monitored by Dipole Potential Measurements

Sokolov

Pohl

2009

Biophysical Journal

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The efficiency of photodynamic reactions depends on 1), the penetration depth of the photosensitizer into the membrane and 2), the sidedness of the target. Molecules which are susceptible to singlet oxygen ((1)O(2)) experience less damage when separated from the photosensitizer by the membrane. Since (1)O(2) lifetime in the membrane environment is orders of magnitude longer than the time required for nonexcited oxygen (O(2)) to cross the membrane, this observation suggests that differences between the permeabilities or membrane partition of (1)O(2) and O(2) exist. We investigated this hypothesis by releasing (1)O(2) at one side of a planar membrane while monitoring the kinetics of target damage at the opposite side of the same membrane. Damage to the target, represented by dipole-modifying molecules (phloretin or phlorizin), was indicated by changes in the interleaflet dipole potential difference Deltaphi(b). A simple analytical model allowed estimation of the (1)O(2) interleaflet concentration difference from the rate at which Deltaphi(b) changed. It confirmed that the lower limit of (1)O(2) permeability is approximately 2 cm/s; i.e., it roughly matches O(2) permeability as predicted by Overton's rule. Consequently, the membrane cannot act as a barrier to (1)O(2) diffusion. Differences in the reaction rates at the cytoplasmic and extracellular membrane leaflets may be attributed only to (1)O(2) quenchers inside the membrane.

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Electrostatic Potentials of Bilayer Lipid Membranes: Basic Principles and Analytical Applications

Cited by 18 publications

References 109 publications

Lipid Membrane Adsorption Determines Photodynamic Efficiency of β-Imidazolyl-Substituted Porphyrins

Lipid Membrane Adsorption Determines Photodynamic Efficiency of β-Imidazolyl-Substituted Porphyrins

A new approach for investigating the response of lipid membranes to electrocompression by coupling droplet mechanics and membrane biophysics

Membrane Transport of Singlet Oxygen Monitored by Dipole Potential Measurements

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