Application of the vibrating plate (VP) technique to measuring electric surface potential, ΔV, of solutions; the flow cell for simultaneous measurement of the ΔV and the surface pressure, Π

Barzyk, Wanda; Vuorinen, Jorma

doi:10.1016/j.colsurfa.2011.03.067

Cited by 9 publications

(8 citation statements)

References 56 publications

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“…5,33 However, for simpler surfactants with opposite charge, opposite potentials have been detected. 34 The absence of sign change indicates that the SPOT measurement on lipid mixtures is not dominated by interfacial charges. Apparently, molecular dipoles play an important role.…”

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confidence: 99%

“…The relatively big impact of the carbonyl groups of the lipid molecules would also explain the discrepancy between the reported results for lipids and surfactants noted earlier. 5,34 Since surfactant molecules lack carbonyl groups, the influence from the oppositely charged headgroups increases and the signal changes sign. The similar dependence on the charge density observed for the SPOT and the carbonyl SFG signals, indicates that the SPOT measurement is dominated by the lipid carbonyl groups.…”

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confidence: 99%

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Surface Potential of a Planar Charged Lipid–Water Interface. What Do Vibrating Plate Methods, Second Harmonic and Sum Frequency Measure?

Dreier

Bernhard

Gonella

et al. 2018

J. Phys. Chem. Lett.

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The interfacial electrical potential is an important parameter influencing, for instance, electrochemical reactions and biomolecular interactions at membranes. A deeper understanding of different methods that measure quantities related to the surface potential is thus of great scientific and technological relevance. We use lipid monolayers with varying charge density and thoroughly compare the results of surface potential measurements performed with the vibrating plate capacitor method and second harmonic generation spectroscopy. The two techniques provide very different results as a function of surface charge. Using the molecular information on lipid alkyl chain, lipid headgroup, and interfacial water provided by sum frequency generation spectroscopy, we disentangle the different contributions to the surface potential measured by the different techniques. Our results show that the two distinct approaches are dominated by different molecular moieties and effects. While the shape of the SPOT method response as a function of charge density is dominated by the lipid carbonyl groups, the SHG results contain contributions from the interfacial water molecules, the lipids and hyper-Rayleigh scattering.

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confidence: 99%

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confidence: 99%

Surface Potential of a Planar Charged Lipid–Water Interface. What Do Vibrating Plate Methods, Second Harmonic and Sum Frequency Measure?

Dreier

Bernhard

Gonella

et al. 2018

J. Phys. Chem. Lett.

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“…Bibliographic references to previous studies can be found in [1][2][3]. Articles on single component fatty acids or related amphiphiles published in the last years are those of [4][5][6][7][8][9][10][11][12][13][14][15][16], and articles on single component phospholipids are those of [17][18][19][20][21][22].…”

Section: Introductionmentioning

confidence: 99%

Thermodynamic Behaviour of Mixed Films of an Unsaturated and a Saturated Polar Lipid. (Oleic Acid-Stearic Acid and POPC-DPPC)

Torrent‐Burgués

2018

Colloids and Interfaces

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Mixed fatty acids or mixed phospholipids systems with saturated-unsaturated hydrocarbon chains are of biological interest. In this work, the monolayers of oleic acid-stearic acid (OA-SA) and palmitoyloleoylphosphatidylcholine-dipalmitoylphosphatidylcholine (POPC-DPPC) have been studied. From the surface pressure-area isotherms, elastic modulus values and virial equation coefficients can be obtained. Thermodynamic treatment also yields excess (G E ) and mixing (∆G mix ) free energies. Results indicate positive G E values, that is, molecular interactions in the mixed films are less favourable, due to the presence of unsaturation; however, the mixture is slightly favourable due to the entropic factor that affords positive ∆G mix values. For the OA-SA system, a high SA content and surface pressure facilitate the phase separation, even though a certain miscibility between both components still remains. For the POPC-DPPC system, the most favourable mixing conditions occur for X POPC ≈ 0.4. For these mixed systems, the values of the elastic modulus are more similar to those of more fluid components (OA or POPC); analysis of the virial coefficients shows that the b 1 virial coefficient values lie between those of the individual components and are higher than values suitable for an ideal mixing.

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“…On the other hand, manual operations in vicinity of the VP made vibrate may cause an uncontrolled shift in the apparatus zero level. (The vibrating plate technique is known of numerous interferences discussed by us in detail in [ 83 ]). Having the above in mind, the initial Δ V values against which the ΔΔ V effect was evaluated were taken just after finishing stirring the solution below the monolayer.…”

Section: Resultsmentioning

confidence: 99%

Penetration of Milk-Derived Antimicrobial Peptides into Phospholipid Monolayers as Model Biomembranes

Barzyk

Rogalska

Więcław-Czapla

2013

Biochemistry Research International

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Three antimicrobial peptides derived from bovine milk proteins were examined with regard to penetration into insoluble monolayers formed with 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) or 1,2-dipalmitoyl-sn-glycero-3-phospho-rac-(1-glycerol) sodium salt (DPPG). Effects on surface pressure (Π) and electric surface potential (ΔV) were measured, Π with a platinum Wilhelmy plate and ΔV with a vibrating plate. The penetration measurements were performed under stationary diffusion conditions and upon the compression of the monolayers. The two type measurements showed greatly different effects of the peptide-lipid interactions. Results of the stationary penetration show that the peptide interactions with DPPC monolayer are weak, repulsive, and nonspecific while the interactions with DPPG monolayer are significant, attractive, and specific. These results are in accord with the fact that antimicrobial peptides disrupt bacteria membranes (negative) while no significant effect on the host membranes (neutral) is observed. No such discrimination was revealed from the compression isotherms. The latter indicate that squeezing the penetrant out of the monolayer upon compression does not allow for establishing the penetration equilibrium, so the monolayer remains supersaturated with the penetrant and shows an under-equilibrium orientation within the entire compression range, practically.

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Application of the vibrating plate (VP) technique to measuring electric surface potential, ΔV, of solutions; the flow cell for simultaneous measurement of the ΔV and the surface pressure, Π

Cited by 9 publications

References 56 publications

Surface Potential of a Planar Charged Lipid–Water Interface. What Do Vibrating Plate Methods, Second Harmonic and Sum Frequency Measure?

Surface Potential of a Planar Charged Lipid–Water Interface. What Do Vibrating Plate Methods, Second Harmonic and Sum Frequency Measure?

Thermodynamic Behaviour of Mixed Films of an Unsaturated and a Saturated Polar Lipid. (Oleic Acid-Stearic Acid and POPC-DPPC)

Penetration of Milk-Derived Antimicrobial Peptides into Phospholipid Monolayers as Model Biomembranes

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