Headgroup Size Research Articles

Lysophospholipid headgroup size, and acyl chain length and saturation differentially affect vacuole acidification, Ca 2+ transport, and fusion.

SNARE-mediated membrane fusion is regulated by the lipid composition of the engaged bilayers. Lipid composition impacts fusion through direct protein lipid interactions or through modulating the physical properties of membranes at the site of contact, including the induction of positive curvature by lysophospholipids (LPLs). The degree of positive curvature induced is due to the length and saturation of the single acyl chain in addition to the size of the head group. Here we examined how yeast vacuole fusion and ion transport were differentially affected by changes in lysolipid properties. We found that lysophosphatidylcholine (LPC) with acyl chains containing 14-18 carbons all inhibited fusion with IC 50 values ranging from ∼40-120 µM. The monounsaturation of LPC-18:1 had no effect when compared to its saturated counterpart LPC-18:0. On the other hand, head group size played a more significant role in blocking fusion as lysophosphatidic acid (LPA)-18:1 failed to fully inhibit fusion. We also show that both Ca 2+ uptake and SNARE-dependent Ca 2+ efflux was sensitive to changes in the acyl chain length and saturation of LPCs, while LPA only affected Ca 2+ efflux. Finally, we tested these LPLs on vacuole acidification by the V-ATPase. This showed that LPC-18:0 could fully inhibit acidification whereas other LPCs had moderate effects. Again, LPA had no effect. Together these data suggest that the effects of LPLs were due to a combination of head group size and acyl chain length leading to a range in degree of positive curvature.

The Role of Lipid Intrinsic Curvature in the Droplet Interface Bilayer.

Model bilayers are constructed from lipids having different intrinsic curvatures using the droplet interface bilayer (DIB) method, and their static physicochemical properties are determined. Geometrical and tensiometric measurements are used to derive the free energy of formation (ΔF) of a two-droplet DIB relative to a pair of isolated aqueous droplets, each decorated with a phospholipid monolayer. The lipid molecules employed have different headgroup sizes but identical hydrophobic tail structure, and each is characterized by an intrinsic curvature value (c0) that increases in absolute value with decreasing size of headgroup. Mixtures of lipids at different ratios were also investigated. The role of curvature stress on the values of ΔF of the respective lipid bilayers in these model membranes is discussed and is illuminated by the observation of a decrement in ΔF that scales as a near linear function of c02. Overall, the results reveal an association that should prove useful in studies of ion channels and other membrane proteins embedded in model droplet bilayer systems that will impact the understanding of protein function in cellular membranes composed of lipids of high and low curvature.

Cytotoxicity of acridinium-based ionic liquids: Structure-activity relationship and mechanistic studies

Ionic liquids (ILs) are a class of low melting point salts with physicochemical properties suitable for a range of industrial applications such as chemical processing and battery design. Major challenges to the wide-scale adoption of ILs in industry include their eco- and cytotoxic effects, however, this opens up the possibility of the use of ILs use as novel anticancer agents. Understanding the structural features that promote IL cytotoxicity is therefore important. Key structural features that can impact IL cytotoxicity include size and lipophilicity of the cationic head group. In this study, the cytotoxic effects of acridinium-based ILs containing relatively large tri- and tetracyclic cations were evaluated. It was found that 9-phenylacridinium-based ILs are potent cytotoxic agents that reduce the viability of human MDA-MB-231 breast cancer cells with IC50 concentrations in the nanomolar range. In mechanistic studies, it was found that unlike the pyridinium-based analogue, [C16Py][I], acridinium-based ILs did not inhibit oxidative phosphorylation or induce reactive oxygen species formation, and may instead target other mitochondrial processes or components such as mitochondrial DNA.

Preferential electrostatic interactions of phosphatidic acid with arginines.

Phosphatidic acid (PA) is an anionic lipid that preferentially interacts with proteins in a diverse set of cellular processes such as transport, apoptosis, and neurotransmission. One such interaction is that of the PA lipids with the proteins of voltage-sensitive ion channels. In comparison to several other similarly charged anionic lipids, PA lipids exhibit much stronger interactions. Intrigued and motivated by this finding, we sought out to gain deeper understanding into the electrostatic interactions of anionic lipids with charged proteins. Using the voltage sensor domain (VSD) of the KvAP channel as a model system, we performed long-timescale atomistic simulations to analyze the interactions of POPA, POPG, and POPI lipids with arginines (ARGs). Our simulations reveal two mechanisms. First, POPA is able to interact not only with surface ARGs but is able to snorkel and interact with a buried arginine. POPG and POPI lipids on the other hand show weak interactions even with both the surface and buried ARGs. Second, deprotonated POPA with -2 charge is able to break the salt-bridge connection between VSD protein segments and establish its own electrostatic bond with the ARG. Based on these findings, we propose a headgroup size hypothesis for preferential solvation of proteins by charged lipids. These findings may be valuable in understanding how PA lipids could be modulating kinematics of transmembrane proteins in cellular membranes.

Study on quantitative structure–activity relationship of amine surfactants in coal reverse flotation

AbstractWith the deterioration of underground coal quality, hundreds of millions of tons of coal slime in China need to be treated using flotation methods every year. However, the design and selection of coal slurry flotation collectors lack theoretical guidance. In this paper, the quantitative structure–activity relationship (QSAR) model between the molecular structure descriptors of collectors and the flotation recovery and selectivity index is established by using pure kaolinite/clean coal flotation experiments and molecular simulation techniques. Flotation results showed that the flotation recovery rate of kaolinite by collectors with larger head group size, such as DDMAC, DDP, and DTAC, is higher than that of the other collectors with smaller head group size. DDA, DDP, and DD have similar flotation capabilities for clean coal, and their selectivity was slightly better than others. The QSAR model between the molecular structure descriptor and the selectivity index was successfully constructed by combining flotation experiments and molecular simulation results. The reliability of this model has been proven through theoretical analysis and flotation experiments. The molecular simulation results indicate that all eight collectors can advertise on 001 (−) surface of kaolinite, but the final advertisement configuration is different. DDA has less coverage on the surface of kaolinite. When the collector is DDA, the concentration of water molecules near the 001 (−) surface of kaolinite is the highest, indicating that the collector DDA has the weakest effect on improving the hydrophobicity of the 001 (−) surface of kaolinite. DDMAC and DDBAC have the best facilitation to the surface hydrophobicity of kaolinite 001 (−). The research results have theoretical guidance significance for the selection and design of mineral flotation collectors.

Interactions of REF1 and SRPP1 rubber particle proteins from Hevea brasiliensis with synthetic phospholipids: Effect of charge and size of lipid headgroup

According to the fatty acid and headgroup compositions of the phospholipids (PL) from Hevea brasiliensis latex, three synthetic PL were selected (i.e. POPA: 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphate POPC: 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine and POPG: 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoglycerol) to investigate the effect of PL headgroup on the interactions with two major proteins of Hevea latex, i.e. Rubber Elongation Factor (REF1) and Small Rubber Particle Protein (SRPP1). Protein/lipid interactions were screened using two models (lipid vesicles in solution or lipid monolayers at air/liquid interface). Calcein leakage, surface pressure, ellipsometry, microscopy and spectroscopy revealed that both REF1 and SRPP1 displayed stronger interactions with anionic POPA and POPG, as compared to zwitterionic POPC. A particular behavior of REF1 was observed when interacting with POPA monolayers (i.e. aggregation + modification of secondary structure from α-helices to β-sheets, characteristic of its amyloid aggregated form), which might be involved in the irreversible coagulation mechanism of Hevea rubber particles.

A proof of concept for the micellization of quercetin with anionic surfactants: Effect of counter ion

Strength of interaction of sodium/ammoniumdodecyl sulfates (SDS and ADS; CH3(CH2)10CH2SO4Na/CH3(CH2)10CH2OSO3NH4) with quercetin (QCT) through micellization is investigated. The strength and mode of interaction of QCT with SDS/ADS was analyzed using uv–visible, FTIR, and NMR spectral techniques. Characteristics of QCT/SDS and QCT/ADS micelles was determined by estimating the critical micellar concentration, particle size and zeta potential values. Thermodynamic parameters ΔG0m and ΔS0m suggest that the micellization of QCT/ADS occurs more spontaneously than QCT/SDS micellization. The small size of head group (-Na+) in SDS exhibits higher steric repulsion upon forming micelles with QCT, whereas the big size head group (-NH4+) in ADS exhibits strong micellization due to additional hydrogen bonding. The results suggests that ADS would be useful in developing QCT based skin formulations which could reduce the risk of surfactant penetration in skin. In this paper we have reported a second cmc of ADS as 0.6 mM which is probably for the first time.

Multiple Routes to Bicontinuous Cubic Liquid Crystal Phases Discovered by High-Throughput Self-Assembly Screening of Multi-Tail Lipidoids.

Bicontinuous cubic phases offer advantageous routes to a broad range of applied materials ranging from drug delivery devices to membranes. However, a priori design of molecules that assemble into these phases remains a technological challenge. In this article, a high-throughput synthesis of lipidoids that undergo protonation-driven self-assembly (PrSA) intoliquid crystalline (LC) phases is conducted. With this screening approach, 12 different multi-tail lipidoid structures capable of assembling into the bicontinuous double gyroid phase are discovered. The large volume of small-angle X-ray scattering (SAXS) data uncovers unexpected design criteria that enable phase selection as a function of lipidoid headgroup size and architecture, tail length and architecture, and counterion identity. Surprisingly, combining branched headgroups with bulky tails forces lipidoids to adopt unconventional pseudo-disc conformations that pack into double gyroid networks, entirely distinct from other synthetic or biological amphiphiles within bicontinuous cubic phases. From a multitude of possible applications, two examples of functional materials from lipidoid liquid crystals are demonstrated. First, the fabrication of gyroid nanostructured films by interfacial PrSA, which are rapidly responsive to the external medium. Second, it is shown that colloidally-dispersed lipidoid cubosomes, for example, for drug delivery, are easily assembled using top-down solvent evaporation methods.

Templated Enzymatic Synthesis of δ-Cyclodextrin.

While α-, β-, and γ-cyclodextrin (CD) are ubiquitous hosts employed by supramolecular chemists, δ-CD (formed from nine α-1,4-linked glucopyranose units) has received very little attention. α-, β-, and γ-CD are the major products of the enzymatic breakdown of starch by cyclodextrin glucanotransferase (CGTase), but δ-CD forms only transiently in this reaction, as a minor component of a complex mixture of linear and cyclic glucans. In this work, we show how δ-CD can be synthesized in unprecedented yields by employing a bolaamphiphile template in an enzyme-mediated dynamic combinatorial library of cyclodextrins. NMR spectroscopy studies revealed that δ-CD can thread up to three bolaamphiphiles forming [2]-, [3]-, or [4]-pseudorotaxanes, depending on the size of the hydrophilic headgroup and the length of the alkyl chain axle. Threading of the first bolaamphiphile occurs in fast exchange on the NMR chemical shift time scale, while subsequent threading occurs in slow exchange. To extract quantitative information for 1:2 and 1:3 binding events occurring in mixed exchange regimes, we derived equations for nonlinear curve fitting that take into consideration both the chemical shift changes for species in fast exchange and the integrals for species in slow exchange to determine Ka1, Ka2, and Ka3. Template T1 could be used to direct the enzymatic synthesis of δ-CD due to the cooperative formation of a 1:2 complex─the [3]-pseudorotaxane δ-CD·T12. Importantly, T1 is recyclable. It can be readily recovered from the enzymatic reaction by precipitation and reused in subsequent syntheses enabling preparative-scale synthesis of δ-CD.

Membrane oxygen permeability is governed by area-per-lipid, combined with headgroup size and cholesterol content.

Molecular oxygen plays critical roles in energy metabolism and anticancer therapeutic strategies. The physical parameters of the cell membrane that may influence tissue oxygenation need further investigation. Here, we present the findings of a study in which tail length, headgroup size, and cholesterol content are considered as variables influencing oxygen permeability. We discover that the oxygen permeability is proportional to the area-per-lipid for single-component phospholipid bilayers. Additionally, we identify headgroup size as a second parameter influencing oxygen permeability (phosphatidylcholine/PC vs. phosphatidylethanolamine/PE). The presence of cholesterol (50 mol%) attenuates the effect of the headgroup size but retains the dependency of oxygen permeability on area-per-lipid. The importance of area-per-lipid as a determinant of oxygen permeability is consistent with the prior finding by Nagle and colleagues that area-per-lipid dominates water permeability. The importance of the headgroup size and cholesterol content are additional insights of our current work.

Packing and elasticity in membrane mechanical properties.

Here we address how membrane properties involving head group size, acyl chain unsaturation, and lipid packing affect their structure and dynamics. Strong out-of-plane proteolipid couplings considered by the flexible surface model (FSM) affect protein function through elastic forces described by the spontaneous curvature and the bending rigidity. We hypothesized that the mechanical properties and the molecular packing resulting from different lipid types are captured by introducing a perdeuterated POPC-d31 probe lipid. Di-monounsaturated phosphatidylcholine and phosphatidylethanolamine (DOPC, DOPE), and different ratios of DOPC/DOPE mixtures were studied using MD simulations combined with experimental solid-state 2H NMR spectroscopy. Residual quadrupolar couplings obtained from de-Paked powder-type spectra yielded order parameter (SCD) profiles for the individual acyl segments giving insights into average membrane structural properties such as area per lipid and bilayer thickness [1]. The corresponding spin-lattice relaxation rates (R1Z) for the resolved peaks followed a theoretical square-law dependence on SCD providing the bending rigidity [2]. Furthermore, MD simulations for the lipid systems were carried out and order parameters were calculated and compared against the NMR-observed SCD values. Utilization of the probe lipid POPC-d31 (1−10 mol%)affected the lamellar to hexagonal phase transition temperature of DOPE lipid systems but did not affect the quadrupolar splittings of DOPE and DOPC systems. Higher bending rigidity was observed for DOPE membranes versus DOPC supporting the idea that the membrane bending rigidity is primarily governed by increased lipid packing and is related to the area-compressibility modulus. Use of a probe lipid to capture membrane mechanical properties of complex lipid systems allow investigation of the relationship of membrane mechanics in vital biological functions.

The mechanism for lowering interfacial tension by extended surfactant containing ethylene oxide and propylene oxide groups

In this work, the interfacial tensions (IFTs) of a series of alkyl ether carboxylates containing different ethylene oxide (EO) and propylene oxide (PO) groups (C12PO15EO5C, C12PO15EO10C and C12PO15EO15C) against n-alkanes were investigated. Based on the experimental and theoretic results, we find that for adsorbed extended surfactant molecules with both PO and EO groups, the PO group stretches towards the oil phase in a helical winding manner, which improves the size of hydrophobic part and decreases IFT. On the other hand, the whole EO group arranges in an “L” pattern with 4 EO flat at the interface and the others stretching into the water. The “dumbbell” type with the large size of the ionic head and PO group at both ends and the linear EO chain in the middle results in the high IFT values. Therefore, a sufficient PO number and few EO number are prerequisites for obtaining ultralow IFT. The addition of NaCl can decrease the size of anionic head and C12PO15EO5C solution can produce ultralow IFT against hydrocarbons at optimized salinity. However, electrolyte shows little effect on the IFTs of extended surfactants with “dumbbell” conformation at the interface because the size of linear EO group plays the crucial role. Our research has important implications for the in-depth understanding of extended surfactants and their application in high-salt reservoirs.

Influence of head group structure of cationic surfactants on the desorption of cesium from clays and clay minerals

The role of cationic surfactants head group for cesium (Cs) desorption from clays and clay minerals was investigated in this study by using two surfactants having similar hydrocarbon chain lengths but different head group types. Two surfactants used were dodecyltrimethylammonium bromide (DTAB) with linear structure and benzyldodecyldimethylammonium bromide (BDAB) containing bulkier head group. The results indicated that Cs desorption from bentonites using both surfactants was accompanied by interlayer expansion. In the case of Na-bentonite, BDAB showed higher Cs desorption efficiency than DTAB due to larger interlayer expansion after intercalation of BDAB. In contrast, the amount of desorbed Cs from Ca-bentonite was comparable, corresponding to the almost identical interlayer expansion after intercalation of both surfactants. It was because Ca ions present in Ca-bentonite must associate with two negatively charged interlayers, hence limiting its expansion. Cs desorption from kaolinite was more governed by surfactant micelles. When the surfactant micelles were formed earlier at low concentration, considerable desorption of Cs was achieved. In this regard, BDAB more efficiently desorbed Cs compared to DTAB owing to rapid formation of BDAB micelles at lower concentrations caused by the increase in head group size. For Cs desorption from illite, both surfactants even exhibited similar insignificant results with HCl used as a control of desorbent. Frayed edge sites in illite probably provoked strong Cs retention causing the difficulty in desorbing Cs. Furthermore, desorption kinetic data of Cs from all samples using both surfactants fitted well with pseudo-second order model, suggesting the occurrence of chemical desorption by involving ion-exchange mechanism.

Insight into the Impact of Oxidative Stress on the Barrier Properties of Lipid Bilayer Models.

As a new field of oxidative stress-based therapy, cold physical plasma is a promising tool for several biomedical applications due to its potential to create a broad diversity of reactive oxygen and nitrogen species (RONS). Although proposed, the impact of plasma-derived RONS on the cell membrane lipids and properties is not fully understood. For this purpose, the changes in the lipid bilayer functionality under oxidative stress generated by an argon plasma jet (kINPen) were investigated by electrochemical techniques. In addition, liquid chromatography-tandem mass spectrometry was employed to analyze the plasma-induced modifications on the model lipids. Various asymmetric bilayers mimicking the structure and properties of the erythrocyte cell membrane were transferred onto a gold electrode surface by Langmuir-Blodgett/Langmuir-Schaefer deposition techniques. A strong impact of cholesterol on membrane permeabilization by plasma-derived species was revealed. Moreover, the maintenance of the barrier properties is influenced by the chemical composition of the head group. Mainly the head group size and its hydrogen bonding capacities are relevant, and phosphatidylcholines are significantly more susceptible than phosphatidylserines and other lipid classes, underlining the high relevance of this lipid class in membrane dynamics and cell physiology.

Supramolecular Glycolipid-Based Hydro-/Organogels with Enzymatic Bioactive Release Ability by Tuning the Chain Length and Headgroup Size.

Designing of supramolecular hydro-/organogels having desired properties, biocompatibility, and stimuli responsiveness is a challenging task. Herein, the gelation ability of amphiphilic glycolipid-based gelators in a wide range of solvents is explored. The structure-function relationship was established by varying the chain length and polar headgroup size of amphiphilic gelators. The prepared hydro-/organogels were characterized by employing several techniques such as differential scanning calorimetry (DSC), rheology, field emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HR-TEM), X-ray diffraction (XRD), etc. The thermal stability of hydro-/organogels increased with an increase in chain length. Rheological analysis depicted that variation in chain length and headgroup size of amphiphilic gelators significantly affected the gel strength and stability. The self-assembled morphology of hydro-/organogel samples revealed the compact entangled fibrillar network structures. After comparing the energy-minimized molecular length with the d-spacing value obtained by XRD, interdigitated bilayer packing in the gel network was established. The bioactive encapsulation and enzymatic release study of hydro-/organogels portrayed their potential application in the biomedical field. To our delight, glycolipid 16M (C16 chain length) formed a molecular hydrogel with injectable and thixotropic behaviors. High critical strain value, thixotropy, injectability, thermoreversibility, and faster bioactive release for the 16M-W hydrogel proved crucial to predict its future applications. Overall, glycolipid amphiphiles designed by upholding proper hydrophilic-lipophilic balance can form multifunctional supramolecular hydrogels with excellent implementation in the drug delivery system.

Cholesterol stiffening of model mammalian and microbial membranes

Cholesterol plays an essential role in mammalian cell membranes by controlling membrane fluidity, organization, and other physicochemical parameters. Such material properties emerge from atomistic level interactions of the lipids with cholesterol [1,2]. Membrane stiffness plays a central role in various biological processes, including vesiculation, protein-membrane interactions, viral budding, and the mechanical stability of cells against pathogen attacks. Our studies show that the degree of membrane stiffening by cholesterol in model di-monounsaturated phosphatidylcholine and phosphatidylethanolamine (DOPC versus DOPE)lipid bilayers depends on both headgroup size and acyl chain unsaturation.

Self‐assembly of gemini amphiphiles with symmetric tails in selective solvent

AbstractGemini amphiphile is a special type of block copolymers formed by connecting two traditional diblock molecules at hydrophilic head groups through spacers. The special structure makes gemini amphiphiles potentially promising for drug delivery and gene delivery. The self‐assembly behavior of gemini amphiphiles with tails of equal length in selective solvent was investigated using the dissipative particle dynamics method. The effects of the size of the hydrophilic head group, interaction parameters, concentration and hydrophobic tail chain length on the self‐assembled morphology of gemini amphiphiles were examined. By varying these parameters, worm‐like micelles, large compound micelles, vesicles, hierarchical rod‐like micelles, cylindrical bundles, pomegranate‐like micelles and bilayers were obtained. Compared with conventional diblock copolymers, the dominant feature of gemini amphiphiles is the presence of the spacer. By analyzing the distance between two head groups, we explored in depth the influence of spacer length on the self‐assembly of gemini amphiphile molecules. Through simulation probes, we hope to improve the understanding of ordered aggregates of gemini amphiphiles in selective solvent, to reveal theoretically the pattern variation of aggregation morphology and to provide guidance for their practical application. © 2022 Society of Industrial Chemistry.

Tail-group unsaturation tailors the surface and self-assembly behavior of C18-fatty acid-based glycolipids

Biosurfactants cover a wide variety of application in diverse fields as interfacial modifiers and drug delivery carriers. Narrow molecular diversity of biosurfactants especially limits their potential application. Herein, we synthesized eight bio-based glycolipids to ascertain the structure–property relationship via changing unsaturation degree of hydrophobic chain and polar glucosidic moiety. The surface parameters of these glycolipids are evaluated with surface tension (ST) and Langmuir Blodgett (LB) studies. The surface-active properties including foaming, wetting, emulsifying, and solubilizing studies were performed to derive the impact of unsaturation degree. Self-assembly properties including critical micelle concentration (CMC), micropolarity, microviscosity, aggregation number (Nagg), and size have been employed to explore impact of unsaturation degree. Studies on encapsulation and enzymatic release of hydrophobic bioactive (curcumin) from glycolipid self-assemblies revealed them as nano-carriers. Interestingly, glycolipids with oleyl chain exhibited excellent hydrophobic encapsulation capacity and release rates are depending on degree of unsaturation and size of headgroup. Results suggest that configuration of unsaturated tail can be tuned to manipulate the interfacial properties and encapsulation-release profile of hydrophobic bioactive.

The role of the polar head group and aliphatic tail in the self-assembly of low molecular weight molecules in oil

The current research explores the involvement of head group size, chemical group type, and aliphatic tail in the molecular self-assembly of various oil structuring agents with similar 18-carbon aliphatic chains and hydroxyl, carbonyl, and/or carboxyl groups, in canola oil. Thermal and mechanical analyses at different molar concentrations emphasized the involvement of van der Waals (vdW) interactions and hydrogen bonds (H-bonds) in the self-assembly process. Higher contribution of vdW-forces in the self-assembly was observed when increasing molecular concentration from medium to high. The presence of H-bonds corresponding with organized crystal structures was detected in samples containing hydroxyl or carboxyl groups using nano-structure analysis. Absence of such groups led to ordered organization only at high concentrations, implying the involvement of vdW interactions. Polarized images demonstrated curved structures for long head group molecules, implying the formation of intermolecular H-bonds with neighboring molecules leading to structure curvature. The current results provide experimental indication to involvement of different forces, i.e. H-bonds and vdW, in the molecular self-assembly of oil structuring agents in oil which can be further exploit while developing new oleogel system based on low molecular weight gelators.

Effect of Oxyethylene Groups of Fatty Alcohol Polyoxyethylene Ether Sodium Sulfates on Equilibrium and Dynamic Surface Tension in Relation to Wetting Properties

Abstract The effect of hydrophilic chain of surfactants fatty alcohol polyoxyethylene ether sodium sulphates (AEnS, n = 2, 3, 7) on surface properties and wetting properties was investigated by the measurement of equilibrium surface tension, dynamic surface tension and dynamic contact angle. The fatty alcohol polyoxyethylene ether sodium sulphates with different head group sizes were used. From the results of equilibrium surface tension measurements, we could obtain the critical micellisation concentration, adsorption efficiency, maximum surface excess concentration and Langmuir equilibrium adsorption constant at air/liquid interface. The dynamic surface tension results showed that the adsorption of aqueous solutions at the air/liquid interface follows a mixed-diffusion kinetic adsorption mechanism. In conclusion, for both studied surfactant, the longer the oxyethylene chains, the higher the maximum rate of surface tension reduction, the higher the diffusivity and wetting properties in terms of contact angle.