Lamellar Liquid Crystalline Phase Research Articles

Endogenous Nonionic Saturated Monoethanolamide Lipids: Solid State, Lyotropic Liquid Crystalline, and Solid Lipid Nanoparticle Dispersion Behavior

The n-acylethanolamides (NAEs) are a family of naturally occurring monoethanolamide containing lipids that display a variety of interesting biological properties. In this study, some physicochemical properties of a series of saturated monoethanolamide lipids with increasing hydrocarbon chain length (lauroyl, myristoyl, palmitoyl, and stearoyl) have been investigated. Temperature induced phase transitions for these NAEs indicate that both the monoethanolamide headgroups and the unsaturated hydrophobic tails play a role in the melting behavior of these lipids. All four lipids examined demonstrate the presence of at least three different polymorphic crystal forms. Transitions in crystal structure can be induced via heating and visualized with polarized optical microscopy. At room and physiological temperature, the four NAEs are solid lamellar crystalline materials. All four molecules form lyotropic liquid crystalline phases in water, albeit at relatively high temperatures, including the lamellar liquid crystalline phase and at least two isotropic phases. Lamellar crystalline palmitoyl monoethanolamide was dispersed as solid lipid nanoparticles (SLNs). The cytotoxicity of these SLNs toward human mammary epithelial cells (HMEpiC) and the MCF7 breast cancer cell line was assessed at physiological temperature. The palmitoyl monoethanolamide SLNs showed little to no toxicity to the HMEpiC even at a concentration of 30 microM. At concentrations above 3 microM, the HMEpiC population was reduced by less than 15%, while the MCF7 population was reduced by approximately 20-30%. The endogenous nature and natural medicinal properties make this series of lipids ideal candidates for further investigation as solid lipid nanoparticle drug delivery systems.

Phase Behavior and Hydrated Solid Structure in Lysophospholipid/Long-chain Alcohol/Water System and Effect of Cholesterol Addition

Phase behavior in lysophospholipid/long-chain alcohol/water system at 80°C was investigated using hexanol and oleyl alcohol as the long-chain alcohol. Similarly to hydrophilic surfactant, a micellar phase in a lysophospholipid/water system transitioned to a lamellar liquid-crystalline phase by the addition of long-chain alcohol. In the oleyl alcohol system the lamellar liquid-crystalline phase was observed in wider region compared to the hexanol system. The effect of cholesterol addition on the phase behavior was also studied. The region of liquid-crystalline phase and (reverse micellar + liquid-crystalline + water) phase shifted towards higher lysophospholipid concentrations. The structure of hydrated solid as well as the transition between lamellar liquid-crystalline phase and hydrated solid was analyzed by X-ray scattering measurement and differential scanning calorimetry measurement. It was revealed that the hydrated solid was α-type crystals with lamellar structure. The hydrated solid (gel)-liquid crystal transition temperature gradually decreased with increasing oleyl alcohol concentration and the decrement was enhanced by the addition of cholesterol.

Nonaqueous foam with outstanding stability in diglycerol monomyristate/olive oil system

We report the formation of nonaqueous foam with outstanding stability in diglycerol monomyristate (designated as C 14G 2) nonionic surfactant in olive oil at 25 °C. Effects of surfactant concentration and added water on foamability and foam stability have been investigated. The C 14G 2 forms the dispersion of surfactant solid in the dilute surfactant concentration regions at 25 °C and they are responsible for the outstanding stability of nonaqueous foams, as they tend to adsorb at the gas–liquid interface. It was found that foamability increases with surfactant concentration up to a certain point, and then level off. In the case of water added system, the foamability increases monotonically with the concentration of water added. Foam stability studies have shown that the foams are stable for a few minutes to several weeks depending on the surfactant concentration and amount of added water. Foam was stable for ∼20 min in 1 wt% C 14G 2/olive oil system, but it was stable more than a month in 10 wt% system. Foam stability of 5 wt% C 14G 2/olive oil system was decreased upon addition of 1 wt% water; foam was stable only for ∼1.5 h. It was found that the average size of the surfactant solid decreases with increasing surfactant concentration and thus foams with better stability could be observed at higher concentrations. The poor foam stability in the water added systems was caused due to structural transition of surfactant solid (α-solid) to lamellar liquid crystalline phase. The present results are obtained by optical microscopy, surface tension, and rheology data.

Supramolecular Architecture in Langmuir Films of a Luminescent Ionic Liquid Crystal

A new luminescent ionic liquid crystal (ILC) with a positive charge in the aromatic central core and two hydrophobic alkyl chains at the ends, called Ipz, has been synthesized and its behavior at the air−liquid (NaCl 2 × 10−6 M) interface has been characterized by combination of surface pressure and surface potential versus area per molecule (π−A and ΔV−A) isotherms, Brewster angle microscopy (BAM) and UV−vis reflection spectroscopy. The results indicate the formation of a supramolecular architecture at the air−liquid interface formed by a head-to-head bilayer on top of a flat-core monolayer. Langmuir films were transferred onto solid substrates, and atomic force microscopy (AFM) and X-ray reflection (XRR) have confirmed that well-ordered multilayer films are obtained. Langmuir films supramolecular structure is different from the molecular organization of Ipz in lamellar liquid-crystalline phases. Furthermore, fluorescence emission spectra reveal a blue shift of the emission band of about 18 nm when compa...

The interplay between grain boundaries and disclinations in condensed matter physics

Abstract The concept of grain boundary, much studied for its relationship with dislocation motion in plastic deformation, is here developed and associated with that of disclination. After defining a disclination in terms of a Volterra process, we investigate the nature of the interplay between both, with application to two cases: i) in polycrystals the triple junctions result from the stress free merging of disclinations bordering the incident grain boundaries; the plastic properties of nanocrystals, which cannot be attributed directly to dislocations, are related to these disclinations; ii) in lamellar liquid crystalline phases grain boundaries are often the place not only of dislocations, but also of focal conic domains, a stunning disclination system described by G. Friedel one hundred years ago.

Phase Behavior of Liquid Crystals Formed in [C12mim]CI/H2O and [C12mim]CI/Alcohols Systems

Phase behaviors of different binary systems involving 1-dodecyl-3-methylimidazolium chloride ([C12mim]Cl) and H2O, [C12mim]Cl and different alcohols (1-butanol, 1-pentanol, 1-hexanol and 1-octanol) are investigated at 25 C. Hexagonal liquid crystal phase (H1) is identified in [C12mim]Cl/H2O system, and lamellar liquid-crystalline (L) phase is found in [C12mim]Cl/alcohols systems by using polarized optical microscopy and small-angle X-ray scattering techniques. The formation of such phases is considered as a synergetic result of the solvatophobic force and the hydrogen-bonded network comprising an imidazolium ring, chloride ion and water (or alcohols), which can be confirmed by Fourier transform infrared spectra. It is noticeable that in [C12mim]Cl/1-octanol system, the lattice spacings of lamellar phase increase with increasing C12mimCl concentration, which is opposite to the results of [C12mim]Cl/H2O system. This may result mainly from stronger static repulsion among hydrophilic headgroups of imidazolium salts arranged in the bilayers of lamellar structures. Further measurements by differential scanning calorimetry indicate that the lamellar phase is stable within a wide temperature range above room temperature. However, the lattice spacings decrease with the increase of temperature, which may be due to the softening of the hydrocarbon chain of [C12mim]Cl molecules. In different alcohols systems, it is found that the lamellar lyotropic liquid crystal structure is easier to be formed when the carbon chain length becomes longer.

Nonequilibrium Phase Transformations at the Air−Liquid Interface

A theoretical model is presented for the formation of an ordered phase close to the air-liquid interface of an open binary aqueous solution. The chemical potential of water in the liquid phase is, in general, not equal to the chemical potential of water in the ambient atmosphere. There are therefore nonequilibrium conditions close to the air-liquid interface. There is also a gradient in the chemical potential of water, which could lead to the formation of a new interfacial phase. The formation of an interfacial phase is analyzed in terms of the equilibrium phase behavior corresponding to the local water chemical potential. The possibility of forming an interfacial phase is strongly dependent on the ambient conditions, bulk composition, and diffusive transport properties of the phases in question. Explicit calculations are presented for the formation of a lamellar liquid-crystalline phase close to the air-liquid interface of an isotropic surfactant solution with parameters chosen from the sodium bis(2-ethylhexyl)sulfosuccinate (AOT)/water system. We consider the relevance of the model to neutron reflectivity studies of the interface between air and surfactant/water systems, as well as to surfactant/polymer/water systems.

Electrolyte Effects on the Stability of Nematic and Lamellar Lyotropic Liquid Crystal Phases: Colligative and Ion-Specific Aspects

We investigated the electrolyte effects on the stability of nematic and lamellar lyotropic liquid crystalline (LLC) phases formed by the simple anionic surfactant cesium pentadecafluorooctanoate (CsPFO) in water. To the lyotropic guest phase, at the constant CsPFO-mass fraction of 0.55, the series of electrolytes LiCl, NaCl, KCl, CsCl, CsI, and Cs(2)SO(4), respectively, was added at concentrations ranging from 0.5 to 2.5 mol %. With increasing electrolyte concentration two substantially different effects were observed. At low concentrations all added electrolytes caused an increase of the thermal stability of the LLC phases, favoring the lamellar phase over the nematic phase. This behavior is, at least qualitatively, understood within the packing parameter model. The extent of the stabilization clearly depends on the chemical nature of the added cation. For a given cation, however, the effect is colligative, i.e., independent of the chemical nature of the added anion. At higher salt concentrations a salting-out-like phase separation was induced. This effect is clearly ion-specific as the salting-out concentration varied for each cation following the order of the Hofmeister series for cations.

Size, Shape, and Charge of Salt-Free Catanionic Microemulsion Droplets: A Small-Angle Neutron Scattering and Modeling Study

The formation and microstructure of a novel microemulsion based on a salt-free catanionic surfactant have been examined by considering the hexadecyltrimethylammonium octylsulfonate (TASo)-decane-D2O system and using small-angle neutron scattering and self-diffusion NMR. With focus on the emulsification failure boundary, o/w discrete droplets have been observed and characterized for all of the studied microemulsion range. The evaluation of the experimental data was facilitated by using structure factors of a model system composed of charged particles interacting with a screened Coulomb potential. Furthermore, a more simplified model involving a charge regulation mechanism has been employed. Both approaches support the view that the droplets are mainly spherical, fairly monodisperse, and charged. The net charge of the surfactant film is a consequence of the partial dissociation of the short-chain counterpart, owing to its higher solubility. We have further quantified how the droplet charge varies with volume fraction and, from that dependence, explained the unusual phase behavior of the TASo-water system, a seldom found coexistence of two lamellar liquid-crystalline phases in a binary system. This coexistence is quantitatively modeled in terms of a fine balance between the attractive and repulsive colloidal forces acting within the system.

Phase Behavior and Kinetics of Phase Separation of a Nonionic Microemulsion of C12E5/Water/1-Chlorotetradecane upon a Temperature Quench

The phase behavior and phase separation kinetics of a model ternary nonionic microemulsion system composed of pentaethylene glycol dodecyl ether (C12E5), water, and 1-chlorotetradecane were studied. With increasing temperature, the microemulsion exhibits the following rich phase behavior: oil-in-water phase (L1+O), droplet microemulsion phase (L1), lamellar liquid crystalline phase (Lproportional), and sponge-like (liquid) phase (L3). The microemulsion with a fixed surfactant-to-oil volume fraction ratio (Phis/Phio) of 0.81 and droplet volume fraction of 0.087 was perturbed from equilibrium by a temperature quench from the L1 region (24 degrees C) to an unstable region L1+O (13 degrees C), where the excess oil phase is in equilibrium with the microemulsion droplets. The process of phase separation in the unstable region was followed by time-resolved small-angle X-ray scattering (TR-SAXS) and time-resolved turbidity methods. Due to the large range of scattering vector (q=0.004-0.22 A(-1)) that is possible to access with the TR-SAXS method, the growth of the oil droplets and shrinking of the microemulsion droplets as a result of phase separation could be studied simultaneously. By using an advanced polydisperse ellipsoidal hard-sphere model, the experimental curves have been quantitatively analyzed. The microemulsion droplets were modeled as polydisperse core-shell ellipsoidal particles, using molecular constraints, and the oil droplets are modeled as polydisperse spheres. The radius of gyration (Rg) of the growing oil droplets, volume fraction of oil in the microemulsion droplets, and polydispersity were obtained from the fit parameters. The volume equivalent radius at the neutral plane between the surfactant head and tail of the microemulsion droplet decreased from 76 to 51 A, while the radius of oil drop increased to 217 A within the 160 min of the experiment. After about 48 min from the temperature quench, the system reaches a steady state and continues to coarsen at a constant fraction of the oil of 0.51 in the oil phase by Ostwald ripening with the power law dependence of Roil proportional, variant t1/3. The size of the oil droplets determined by the time-resolved turbidity method is in good agreement with that of the TR-SAXS, highlighting the usefulness of the method in the size determination of oil-in-water microemulsions on an absolute scale.

Barotropic and thermotropic bilayer phase behavior of positional isomers of unsaturated mixed-chain phosphatidylcholines

The bilayer phase transitions of six kinds of mixed-chain phosphatidylcholines (PCs) with an unsaturated acyl chain in the sn-1 or sn-2 position, 1-oleoyl-2-stearoyl- (OSPC), 1-stearoyl-2-oleoyl- (SOPC), 1-oleoyl-2-palmitoyl- (OPPC), 1-palmitoyl-2-oleoyl- (POPC), 1-oleoyl-2-myristoyl- (OMPC) and 1-myristoyl-2-oleoyl- sn-glycero-3-phosphocholine (MOPC), were observed by means of differential scanning calorimetry (DSC) and high-pressure light transmittance measurements. Bilayer membranes of SOPC, POPC and MOPC with an unsaturated acyl chain in the sn-2 position exhibited only one phase transition, which was identified as the main transition between the lamellar gel (L β) and liquid crystalline (L α) phases. On the other hand, the bilayer membranes of OSPC, OPPC and OMPC with an unsaturated acyl chain in the sn-1 position exhibited not only the main transition but also a transition from the lamellar crystal (L c) to the L β (or L α) phase. The stability of their gel phases was markedly affected by pressure and chain length of the saturated acyl chain in the sn-2 position. Considering the effective chain lengths of unsaturated mixed-chain PCs, the difference in the effective chain length between the sn-1 and sn-2 acyl chains was proven to be closely related to the temperature difference of the main transition. That is, a mismatch of the effective chain length promotes a temperature difference of the main transition between the positional isomers. Anomalously small volume changes of the L c/L α transition for the OPPC and OMPC bilayers were found despite their large enthalpy changes. This behavior is attributable to the existence of a cis double bond and to significant inequivalence between the sn-1 and sn-2 acyl chains, which brings about a small volume change for chain melting due to loose chain packing, corresponding to a large partial molar volume, even in the L c phase. Further, the bilayer behavior of unsaturated mixed-chain PCs containing an unsaturated acyl chain in the sn-1 or sn-2 position was well explained by the chemical-potential diagram of a lipid in each phase.

Development of Novel Multifunctional Cosmetic Raw Materials and Their Applications. IV. The Effect of Structure of Polyoxyethylene / Polyoxypropylene Derivative on the Self-organizing Structures of Surfactants

In this study, the effect of a random copolymer of polyoxyethylene (POE, 38 mol)/polyoxypropylene (POP, 10 mol) pentaerythrytol tetramethyl ether [PEPTME (38/10)], which is unable to form a self-organizing structure on account of its bulkiness, on the microemulsion phase was examined. The phase diagram of the liquid paraffin - nonionic surfactant+PEPTME (38/10) - water system was compared with that of polyoxyethylene (POE)/polyoxypropylene (POP) dimethyl ether (EPDME) system which has a straight-chain structure. In the previous study, the authors reported that a special droplet type microemulsion (highly concentrated microemulsion) was formed, when EPDME was distributed in the hydrophilic moiety of a surfactant in a lamellar liquid crystalline phase. In contrast, it was found that the use of PEPTME (38/10) resulted in disappearance of lamellar as well as hexagonal and cubic liquid crystals, and the formation of an optically isotropic and fluid phase owing to the relationship between the original microemulsion phase and the highly concentrated microemulsion phase. Thus, PEPTME (38/10) was considered to be most suited for preparing highly concentrated microemulsions.

Aqueous foam stabilized by polyoxyethylene dodecyl ether

AbstractFoaming properties of aqueous solutions of the nonionic surfactant polyoxyethylene dodecyl ether (C12EOn) were studied at 298 K. Four different EO chain lengths, namely C12EO3, C12EO5, C12EO7, and C12EO9, were considered. The foams obtained from C12EO3 or C12EO5 were extraordinary stable retaining a constant volume for more than 20 h. The presence of lamellar liquid crystalline phases was mainly responsible for the super-stable aqueous foams.

Natural Surfactant-Based Emulsion Systems: The Influence of Common Pharmaceutical Excipients on Colloidal Structure and Physical Stability

There is a growing need for research into new skin- and environment-friendly surfactants. The aim of the study was to find out whether a combination of an alkylpolyglucoside natural surfactant with established pharmaceutical excipients could provide a solid pharmaceutical base with satisfied physical stability. The study was carried out in two phases: the first one focused on the colloidal structure of vehicles formulated with oils of different polarity and/or different costabilizer (lipophilic versus hydrophilic) and the second one evaluated vehicles' physical stability. A number of techniques were used (polarization, light, and transmission electron microscopy, pH, conductivity and thermogravimetric measurements, rheological analysis and cyclic temperature stress test). Natural surfactant's interaction with used excipients resulted in the formation of semisolid emulsion systems of different rheological profiles, stabilized predominantly by synergistic effects of lamellar liquid-crystalline (Lα) and complex lamellar gel (Lβ) phases. The type of used oil and costabilizer significantly influenced the colloidal structure of the vehicles, particularly in terms of water distribution mode and initial rheological performance as well as their physical stability. It was recommended that medium polar oils of ester type and lipophilic costabilizers, particularly long chain fatty alcohols, should be used in the formulation of stable alkylpolyglucoside-based topical vehicles.

Stabilization of foams solely with polyoxyethylene-type nonionic surfactant

Long-term stability is desirable for many foam-based systems, but achieving it is rather difficult. We report how foams can be stabilized solely with nonionic surfactant of the polyoxyethylene dodecyl ether (C 12EO n ). Effects of concentration and EO chain length of surfactants namely C 12EO 3, C 12EO 5, C 12EO 7 and C 12EO 9 on foaming properties (foamability and foam stability) were considered. The liquid drainage profiles of foams prepared were determined by reading the volume of the liquid drained as a function of time. The microstructure and viscosities on these colloidal systems were studied using optical microscopy and viscosimeter in attempt to explore the stability mechanisms. The experimental results suggest that the foamability goes through a maximum at the concentration of 10 wt.%, respectively, except for C 12EO 7. The optimal concentration of C 12EO 7 displaying maximum foaming capacity is at 1 wt.%. The stability of foams increases with increment of surfactant concentration. Foams stabilized solely by C 12EO 3 and C 12EO 5 at the concentration of 30 wt.%, respectively, exhibit the presence of lamellar liquid crystal adsorbed at the air/liquid interface, and could maintain more than 20 h without occurrence of collapse. In the case of foams generated from C 12EO 7 and C 12EO 9 under same concentration, respectively, there is no any optical fine structure between two air bubbles and thus has a poor stability only for tens of minutes. It is concluded that the stability of foams stabilized solely by C 12EO n surface active agents is attributed to the presence of lamellar liquid crystalline phases located at the gas/liquid interface. The role of liquid crystal in stabilizing foams could be explained in several mechanisms including hydrodynamic drainage, the mechanical strength of the liquid film and the diffusion rate of entrapped gas. The drainage behavior from these foams was well fitted by the empirical equation V t = V max t n /( K n + t n ) and the mechanism of liquid drainage was also discussed.

Synthesis of α- and β-FeOOH iron oxide nanoparticles in non-ionic surfactant medium

Forced hydrolysis of Fe(III) ions in acidic media was performed under controlled synthetic conditions to produce α- and β-FeOOH iron oxides. The forced hydrolysis synthesis was carried out, separately, in an aqueous medium and the lamellar lyotropic liquid crystalline phase of a commercial non-ionic surfactant/water system. The FT-IR analyses confirmed formation of α- and β-FeOOH iron oxides in the aqueous and the surfactant media with slight formation of ferrihydrite and haematite. TEM micrographs have shown that particles formed in the lamellar lyotropic phase are smaller than those produced in the aqueous medium with their smallest size dimension being constrained in the nanometre scale with a size ranging between 5 and 100 nm. Particles produced in the nanoscale size appeared to have different optical properties compared to their counterparts produced in the microscale size.

Calorimetric and EPR studies of the thermotropic phase behavior of phospholipid membranes

Transmission electron micrographs (TEM) showed that liposome vesicles prepared from DL-α-phosphatidylcholine dimyristoyl (1,2-ditetradecanoyl-rac-glycerol-3-phosphocholine) (DMPC) by the modified reverse-phase evaporation method (mREV) were spherical in shape and in majority of them were less than 100 nm in diameter. Differential scanning calorimetry (DSC) method was used to determine the influence of cholesterol content and pH of Tris-HCl buffer used for the preparation of liposomes on the temperature of phase transition T C of phospholipids which form the investigated liposome vesicles. The use of DSC method made it possible to determine not only the temperature of the main phase transition of phospholipids but also the temperature of the phospholipid phase transition from the tilted gel phase(L β′) to the ripple gel phase(P β′). The results were compared with those obtained with EPR study. EPR study was carried out in the temperature range from 284 to 310 K i.e. below and above the phase transition temperature T C of DMPC. On the basis of EPR spectra of spin marker 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) incorporated into the liposome, the values of parameters f were determined. Hence TEMPO can be used to observe the change in partition between aqueous and fluid lipid regions. The change in the relative values of f determined for DMPC as a function of temperature shows that this phospholipid undergoes a transition from a ‘gel phase’ to a lamellar smectic liquid crystalline phase in the presence of excess water. The EPR study of TEMPO allowed us to determine the transition temperature T C. The results were compared with those obtained with DSC method.

Cover Picture: Distinct Columnar and Lamellar Liquid Crystalline Phases Formed by New Bolaamphiphiles with Linear and Branched Lateral Hydrocarbon Chains (Chem. Eur. J. 21/2008)

Polyphilic T-shaped molecules self-assemble into new liquid-crystalline phases in which rodlike aromatic units form arrays of polygonal cylinders that are fused by hydrogen-bonding networks running along the edges to give honeycomb-like networks in which the cells are filled by fluid alkyl chains. A range of different molecular structures are reported in the Full Paper by C. Tschierske et al. on page 6352 ff.

Distinct Columnar and Lamellar Liquid Crystalline Phases Formed by New Bolaamphiphiles with Linear and Branched Lateral Hydrocarbon Chains

A universal building block for the convergent synthesis of a wide variety of different T-shaped ternary amphiphiles was developed and used for the synthesis of a series of new liquid-crystalline materials composed of a rigid biphenyl core with polar glycerol groups at both ends and linear or branched alkyl chains in a lateral position. In addition, compounds with bulky achiral (2,4,6-trimethylphenoxy, adamantane-1-carboxylate, benzoate) or chiral (menthyl or cholesteryl) substituents attached to the end of the lateral alkyl chain were also investigated. In all cases the lateral chains were connected to the aromatic core by an ether linkage. The effect of the ether linking unit on mesophase stability and mesophase type is discussed with respect to conformational effects. The liquid-crystalline phases were investigated by polarizing microscopy, calorimetry, and X-ray diffraction of surface aligned samples. Upon enlarging the lateral chains a series of different polygonal cylinder phases was observed, which were replaced by lamellar phases and a non-cylinder hexagonal columnar phase by further increasing the size of these substituents. Remarkably, only pentagonal, hexagonal, and giant hexagonal cylinder phases could be observed, whereas mesophases composed of cylinders with a smaller number of sides are missing. No distinct chirality effects were observed for the menthyl- and cholesteryl-substituted compounds. However, the rodlike shape of the polycyclic cholesteryl core leads to a unique phase structure combining an organization of the alicyclic cholesteryl cores perpendicular to the layer planes and the aromatic biphenyl cores parallel to the layer planes.

Lateral Diffusion of Lipids and Diffusion of Water through Lipid Bilayers in the Presence of (1,1-Dimethyl-3-Oxobutyl)Phosphonates

The influence of some amphiphilic (diethyl, dipropyl, and dibutyl) esters of (1,1-dimethyl-3-oxobu- tyl)phosphonic acid with the regularly changing number of CH 2 groups in the hydrocarbon (hydrophobic) moi- ety on the lateral diffusion of dioleoyl phosphatidylcholine lipid and transmembrane diffusion of water in the oriented multibilayer system was studied by 1 H pulsed field gradient NMR at phosphonate concentrations up to 30 mol %. The shape of the 31 P NMR spectra and the dependence of the shape of the 1 H NMR spectra on the bilayer orientation suggest that the presence of phosphonates does not affect the phase state of the system. The lamellar liquid crystalline phase remains unchanged, and phosphonate molecules become incorporated into the bilayer and have the same orientation as phospholipid molecules. The presence of phosphonates in the lipid bilayer increases the coefficients of lipid lateral diffusion and water diffusion through bilayers. This effect depends monotonically on the number of CH 2 groups in the phosphonate molecule. The most probable place for the incorporation of amphiphilic phosphonate molecules is the hydrophilic/hydrophobic interphase region of the bilayer. The molecules incorporated into the interphase disorder the bilayer and increase lateral diffusion of lipids and bilayer permeability compared with the ester-free bilayer. When the number of CH 2 groups in the ester molecule increases from diethyl to dibutyl phosphonate, the arrangement of lipid hydrocarbon tails becomes more ordered. This decreases the lipid lateral diffusion coefficient and bilayer permeability to water molecules.