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Discerning perturbed assembly of lipids in a model membrane in presence of violacein. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2021; 1863:183647. [PMID: 33989532 DOI: 10.1016/j.bbamem.2021.183647] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 12/20/2020] [Revised: 05/01/2021] [Accepted: 05/07/2021] [Indexed: 12/13/2022]
Abstract
Violacein is a naturally found pigment that is used by some gram negative bacteria to defend themselves from various gram positive bacteria. As a result, this molecule has caught attention for its potential biomedical applications and has already shown promising outcomes as an antiviral, an antibacterial, and an anti-tumor agent. Understanding the interaction of this molecule with a cellular membrane is an essential step to extend its use in the pharmaceutical paradigm. Here, the interaction of violacein with a lipid monolayer formed at the air-water interface is found to depend on electrostatic nature of lipids. In presence of violacein, the two dimensional (2D) pressure-area isotherms of lipids have exhibited changes in their phase transition pressure and in-plane elasticity. To gain insights into the out-of-plane structural organization of lipids in a membrane, X-ray reflectivity (XRR) study on a solid supported lipid monolayer on a hydrophilic substrate has been performed. It has revealed that the increase in membrane thickness is more pronounced in the zwitterionic and positively charged lipids compared to the negatively charged one. Further, the lipid molecules are observed to decrease their tilt angle made with the normal of lipid membrane along with an alteration in their in-plane ordering. This has been quantified by grazing incidence X-ray diffraction (GIXD) experiments on the multilayer membrane formed in an environment with controlled humidity. The structural reorganization of lipid molecules in presence of violacein can be utilized to provide a detailed mechanism of the interaction of this molecule with cellular membrane.
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Micro-Surface and -Interfacial Tensions Measured Using the Micropipette Technique: Applications in Ultrasound-Microbubbles, Oil-Recovery, Lung-Surfactants, Nanoprecipitation, and Microfluidics. MICROMACHINES 2019; 10:mi10020105. [PMID: 30717224 PMCID: PMC6413238 DOI: 10.3390/mi10020105] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Revised: 01/23/2019] [Accepted: 01/25/2019] [Indexed: 01/08/2023]
Abstract
This review presents a series of measurements of the surface and interfacial tensions we have been able to make using the micropipette technique. These include: equilibrium tensions at the air-water surface and oil-water interface, as well as equilibrium and dynamic adsorption of water-soluble surfactants and water-insoluble and lipids. At its essence, the micropipette technique is one of capillary-action, glass-wetting, and applied pressure. A micropipette, as a parallel or tapered shaft, is mounted horizontally in a microchamber and viewed in an inverted microscope. When filled with air or oil, and inserted into an aqueous-filled chamber, the position of the surface or interface meniscus is controlled by applied micropipette pressure. The position and hence radius of curvature of the meniscus can be moved in a controlled fashion from dimensions associated with the capillary tip (~5–10 μm), to back down the micropipette that can taper out to 450 μm. All measurements are therefore actually made at the microscale. Following the Young–Laplace equation and geometry of the capillary, the surface or interfacial tension value is simply obtained from the radius of the meniscus in the tapered pipette and the applied pressure to keep it there. Motivated by Franklin’s early experiments that demonstrated molecularity and monolayer formation, we also give a brief potted-historical perspective that includes fundamental surfactancy driven by margarine, the first use of a micropipette to circuitously measure bilayer membrane tensions and free energies of formation, and its basis for revolutionising the study and applications of membrane ion-channels in Droplet Interface Bilayers. Finally, we give five examples of where our measurements have had an impact on applications in micro-surfaces and microfluidics, including gas microbubbles for ultrasound contrast; interfacial tensions for micro-oil droplets in oil recovery; surface tensions and tensions-in-the surface for natural and synthetic lung surfactants; interfacial tension in nanoprecipitation; and micro-surface tensions in microfluidics.
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Pallas NR, Pethica BA. Intermolecular forces in lipid monolayers. Two-dimensional virial coefficients for pentadecanoic acid from micromanometry on spread monolayers at the air/water interface. Phys Chem Chem Phys 2009; 11:5028-34. [DOI: 10.1039/b820460h] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Equilibrium Adsorption of Surfactants at the Gas–Liquid Interface. ADVANCES IN POLYMER SCIENCE 2008. [DOI: 10.1007/12_2008_161] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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Pethica BA, Glasser ML. Lateral intermolecular forces in the physisorbed state: surface field polarization of benzene and n-hexane at the water/ and mercury/vapor interfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2005; 21:944-949. [PMID: 15667172 DOI: 10.1021/la040090b] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The available experimental data on the dependence of the surface tensions of water and mercury on the adsorption of benzene and hexane from the vapor phase are critically analyzed and interpreted to obtain the two-dimensional second virial coefficients [B(2)(T)] for these adsorbed nonpolar molecules. Calculations based on the unperturbed Lennard-Jones (L-J) 12-6 formalism for benzene and the related 12-5 Salem formalism for long chains in two dimensions for hexane require that B(2)(T) should be negative for both adsorbates. On water, the experimental data indicate that B(2)(T) for both molecules is less negative than expected from the unperturbed L-J and Salem estimates, and on mercury the B(2)(T) values from experiment are positive. These findings are analyzed first in terms of a possible reduction in the attractive component of the potential of mean force between physisorbed molecules arising from their frequency-dependent interaction with their electrostatic images in the bulk phases, as described by McLachlan. It is concluded that the McLachlan corrections are small for these molecules and surfaces. A second analysis considers the effect of an extra repulsion between the adsorbed molecules arising from the induction of dipoles normal to the interface by the surface electric field. Surface field polarization (SFP) accounts reasonably well for the experimental results, leading to estimates of the surface fields at the mercury and water surfaces which are consistent with estimates from contact potentials for mercury and computation from modeling the water surface. SFP may have a wide impact in determining the form of physisorption isotherms.
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Affiliation(s)
- Brian A Pethica
- Department of Chemical Engineering, Princeton University, Princeton, NJ 08544, USA
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Karakashev S, Manev E, Nguyen A. Interpretation of negative values of the interaction parameter in the adsorption equation through the effects of surface layer heterogeneity. Adv Colloid Interface Sci 2004; 112:31-6. [PMID: 15581552 DOI: 10.1016/j.cis.2004.06.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The problem of the negative values of the interaction parameter in the equation of Frumkin has been analyzed with respect to the adsorption of nonionic molecules on energetically homogeneous surface. For this purpose, the adsorption states of a homologue series of ethoxylated nonionic surfactants on air/water interface have been determined using four different models and literature data (surface tension isotherms). The results obtained with the Frumkin adsorption isotherm imply repulsion between the adsorbed species (corresponding to negative values of the interaction parameter), while the classical lattice theory for energetically homogeneous surface (e.g., water/air) admits attraction alone. It appears that this serious contradiction can be overcome by assuming heterogeneity in the adsorption layer, that is, effects of partial condensation (formation of aggregates) on the surface. Such a phenomenon is suggested in the Fainerman-Lucassen-Reynders-Miller (FLM) "Aggregation model". Despite the limitations of the latter model (e.g., monodispersity of the aggregates), we have been able to estimate the sign and the order of magnitude of Frumkin's interaction parameter and the range of the aggregation numbers of the surface species.
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Affiliation(s)
- Stoyan Karakashev
- Discipline of Chemical Engineering, School of Engineering, The University of Newcastle, University Drive, Callaghan, NSW 2308, Australia.
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Faure N, Bouloussa O, Rondelez F. Influence of multivalent counterions adsorption on Langmuir films. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2004; 15:149-158. [PMID: 15549596 DOI: 10.1140/epje/i2004-10042-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
It has been shown recently by neutron and X-ray reflectivity that nanometer-sized multivalent counterions (Keggin salts) can assemble as a dense monomolecular sublayer beneath a charged Langmuir monolayer of opposite sign. We have conducted experiments that examine the surface pressure isotherms of docosamine surfactant monolayers under such conditions and have shown that they undergo dramatic modifications when the Keggin salts are added. We model these experimental results by a close-packed sublayer of counterions on which charged surfactants can organize and form complexes. We then provide a thermodynamic description of the surface/sublayer system by giving an expression for surface free energy and surface pressure. We compare the results of this discrete model to traditional mean-field descriptions where the counterions form a diffuse continuous layer. The new features are: i) modifications in the shape of the surface pressure isotherm; ii) appearance of a phase separation in the surfactant layer. Finally, we show that the model is in satisfactory agreement with the experimental isotherms and a best fit yields numerical estimates of the different interaction parameters.
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Affiliation(s)
- N Faure
- Laboratoire de Physico Chimie Curie (PCC), CNRS UMR 168 and Institut Curie, 11 rue Pierre et Marie Curie, 75231 Paris Cedex 05, France
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Karakashev SI, Manev ED. Effect of Interactions between the Adsorbed Species on the Properties of Single and Mixed-Surfactant Monolayers at the Air/Water Interface. J Colloid Interface Sci 2002; 248:477-86. [PMID: 16290553 DOI: 10.1006/jcis.2001.8206] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2001] [Accepted: 12/27/2001] [Indexed: 11/22/2022]
Abstract
Experimental data on surface tension available from the literature and generated in the present study are analyzed to estimate the applicability of adsorption models, based on the Frumkin equation, to nonionic and ionic surfactants and their mixtures. Optimization programs based on the least-squares method in media of Delphi V and Pascal VII are used. The effect of interactions between the adsorbed species on surface tension is considered in all cases. The results are compared to those obtained with the simpler Szyszkowski equation, employed in numerous studies of nonionic surfactants, when interactions are neglected. Cases where the Frumkin model can be successfully employed with ionic surfactants and mixtures are presented and the conditions of its applicability are analyzed. Related characteristic quantities (maximum adsorption, standard free energy of surfactant adsorption, energy of interaction between adsorbed species, standard free energy of counterion adsorption, degree of coverage by surfactant/counterion associates) are established as a function of: The properties of an adsorption layer from a mixture of nonionic and ionic surface-active species are compared to those of the single surfactants.
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Affiliation(s)
- Stoyan I Karakashev
- Faculty of Chemistry, St. Kliment Ohridski University of Sofia, Sofia, 1126, Bulgaria
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Pethica BA, Senak L, Zhu Z, Lou A. Surface and colloidal properties of cyclic amides. 5. N-cyclohexyl-2-pyrrolidone–water mixtures aggregation in solution and adsorption at the air–solution interface. Colloids Surf A Physicochem Eng Asp 2001. [DOI: 10.1016/s0927-7757(01)00490-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Urbina-Villalba G, Reif I. Simple theoretical framework for a systematic molecular dynamics study of the interfacial properties of oil/water systems in the presence of surfactant molecules. Colloids Surf A Physicochem Eng Asp 1996. [DOI: 10.1016/0927-7757(95)03377-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
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Interfacial properties of mixtures of lecithin with a block copolymer surfactant at the water/air and water/oil interfaces. Colloid Polym Sci 1995. [DOI: 10.1007/bf00656889] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Equilibrium position of carboxylic acid molecules in monolayers on aqueous subphases. J Colloid Interface Sci 1992. [DOI: 10.1016/0021-9797(92)90410-n] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Interfacial properties of mixtures of sorbitan sesquioleate with a block copolymer surfactant at the water/air and water/oil interfaces. ACTA ACUST UNITED AC 1992. [DOI: 10.1016/0166-6622(92)80034-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Surface pressure-area isotherms for a block copolymer surfactant at the water/air and water/oil interfaces. ACTA ACUST UNITED AC 1990. [DOI: 10.1016/0166-6622(90)80136-r] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Niccolai A, Baglioni P, Dei L, Gabrielli G. Monolayers of 1,2,3-propanetriol esters at the air-water interface: two-dimensional phases and miscibility. Colloid Polym Sci 1989. [DOI: 10.1007/bf01410584] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Gabrielli G, Niccolai A, Dei L. Monolayers of stearic acid esters at the air-water interface: two-dimensional phases and miscibility. Colloid Polym Sci 1986. [DOI: 10.1007/bf01410862] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Friberg SE, Osborne DW. A lamellar liquid crystal as an in situ surface balance II. The conformation of 2-(alkoyloxy)-1[(alkoyloxy)methyl]-ethyl-7-(4-heptyl-5,6-dicarboxyl-2-cyclohexene-1-yl) heptanoate. Colloid Polym Sci 1986. [DOI: 10.1007/bf01414847] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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22
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Bertrand GL. An ideal associated gas film model for highly expanded surface films. J Colloid Interface Sci 1982. [DOI: 10.1016/0021-9797(82)90279-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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