Micelle Interface Research Articles

Stability of trianionic curcumin enhanced by gemini alkyl O-Glucosides and alkyl trimethyl ammonium halides mixed micelles

Improved capability to inhibit degradation of trianionic curcumin has been realized in this study. The interaction between trianionic curcumin (Cur3−) and gemini dodecyl or tetradecyl O-glucoside micelles, tetradecyltrimethylammonium chloride (TTAC) or hexadecyltrimethylammonium bromide (CTAB) micelles as well as gemini alkyl O-glucosides (AGs)/alkyl trimethyl ammonium halides mixed micelles have been characterized. It is demonstrated that Cur3− cannot be incorporated into gemini AGs micelles since the lack of electrostatic attraction and degraded as rapidly as in aqueous phase. Cur3− tend to reside at palisade layer − water interface of TTAC or CTAB micelles due to the strong electrostatic interaction while moderate electrostatic interaction allows Cur3− to locate more deeply in the palisade layer of mixed micelles. Additionally, mixed micelles tend to form a more compact and hydrophobic palisade layer than pure TTAC and CTAB ones. These factors bring about enhanced fluorescence intensity and blue − shift of emission maxima, improved fluorescence anisotropy and quantum yield, as well as reduced decay rate of Cur3− in mixed micelles than in pure TTAC and CTAB ones.

Hydrophobically Tailored Carbon Dots toward Modulating Microstructure of Reverse Micelle and Amplification of Lipase Catalytic Response.

This article delineates the modulation of microstructure of cationic reverse micelle utilizing hydrophobically modified carbon dots (CDs) with varying surface functionalizations. Citric acid was used as the source of the carbon core, and Na-salt of glycine, glycine, Na-salt of 11-aminoundecanoic acid, 11-aminoundecanoic acid, and n-hexadecylamine were used for the surface fabrication of CDs to produce CD 1s, CD 1a, CD 2s, CD 2a, and CD 3, respectively. All these CDs having dimension of 5-7 nm were characterized by spectroscopic and microscopic techniques. The hydrodynamic diameter of cetyltrimethylammonium bromide (CTAB) reverse micelle (CTAB/isooctane/n-hexanol/water) at z ([cosurfactant]/[surfactant]) = 6.4 and W0 ([water]/[surfactant]) = 44 is around 15-20 nm. Interestingly, the size of the water-in-oil (w/o) microemulsions dramatically increased up to 120-200 nm upon doping hydrophobic surface functionalized CD 2a and CD 3. This is possibly due to change in the micellar exchange dynamics and reorganization of the micellar aggregates via hydrophobic interaction between surfactant (CTAB) tail and hydrophobic surface modifier of the carbon dots. However, no alteration in the size of reverse micelles was noted in the presence of carbon dots CD 1s, CD 1a, and CD 2s. Spectroscopic and microscopic investigations confirmed that the hydrophobic CD 2a and CD 3 were localized at the interface of reverse micelles whereas CD 1s, CD 1a, and CD 2s were possibly located in the water pool (away from interface). The activity of Chromobacterium viscosum lipase encapsulated within CD 3 and CD 2a doped significantly large CTAB reverse micelles showed remarkable improvement (3.7-fold and 3.4-fold) in its catalytic response. However, hydrophilic carbon dots CD 1s and CD 2s as well as moderately hydrophobic CD 1a had no significant effect on the microstructure of reverse micelles as well as on the lipase activity.

In situ embedding of ultra-fine nickel oxide nanoparticles in HMS with enhanced catalytic activities of styrene epoxidation

In this paper, a new templating assemble route (S0M+I−) was proposed to construct a nickel-based mesoporous silica catalyst. During this method, the neutral surfactant dodecyl amine was used as a special agent for both capturing the metal ions and structure-directing of the mesoporous silica. Based on the templating assemble route, metal cations were highly enriched in the interface of micelles and silicate wall by the physiochemical interaction among the surfactant (S0), metal cations (M+, Ni2+) and silicate oligomers (I−). Besides, instead of original hydrogen-bonding, the addition of metal cations in the assemble process made the interaction between micelles and silicate oligomers improved significantly through the counterion-mediated interaction. According to these effects, highly-dispersed, ultra-fine and accessible nickel oxide nanoparticles (NPs) were in situ produced and embedded in the channels and the exposed level of the active sites on these NPs would reach to the highest. Moreover, as expected, the synthesized catalyst exhibited superior catalytic activities for the epoxidation of styrene.

Synthesis, structural characterization, modal membrane interaction and anti-tumor cell line studies of nitrophenyl ferrocenes

A series of nitrophenyl ferrocens (A1 – A5) were synthesized and fully characterized in solid state (using CHN analysis, FTIR and single crystal XRD) as well as in solution phase (1H &13C NMR and UV–visible spectroscopy). Micelle interface interactions of these compounds were explored and found to have ability across a micelle membrane interface. Interestingly, these compounds exhibited π–electronic push pull systems and oxidation of ferrocene to ferrocenium on crossing the negative interface of the micelle membrane. Selective compounds were screened for antitumor activity against parental and drug resistant human ovarian tumor models i.e. A2780 and A2780cisR, A2780ZD0473R. Screened compounds were found to overcome resistance factor compared to cisplatin.

Interaction of 6-methoxyquinoline with anionic sodium dodecylsulfate micelles: Photophysics and rotational relaxation dynamics at different pH

Interactions of different species of 6-methoxyquinoline (6MQ) with anionic micelles have been studied at different pre-micellar, micellar and post-micellar concentrations using steady state, time resolved fluorescence and fluorescence anisotropy techniques. The sensitivity of fluorescence of 6MQ to change in its local environment was used to probe sodium dodecylsulfate (SDS) micelles. At post-micellar concentrations of SDS, the observed blue shift in the fluorescence spectrum and increase in quantum yield are attributed to the incorporation of solute molecule to micelles. 6MQ has been found to bind to the surface of the anionic micelles instead of penetrating inside the core of micelles. The binding constant (Kb) calculated for 6MQ revealed that the electrostatic forces mediate charged probe–micelle association, whereas, hydrophobic interaction allowed neutral 6MQ to associate with SDS micelles. The charged 6MQ gets inserted deeper into the micelle surface than its neutral form. The fluorescence anisotropy decay of 6MQ in SDS micelles studied at different pH allowed determination of restriction of motion of the fluorophore. The location of the probe molecule in micellar systems is justified by a variety of spectral parameters such as refractive index, dielectric constant, ET(30), average fluorescence decay time, radiative and non-radiative rate constants, and rotational relaxation time. The micro-environment around the fluorophore reveals that the photophysics of 6MQ is very sensitive to the microenvironment of SDS and probe molecules reside at the water–micelle interface.

How the cation 1-butyl-3-methylimidazolium impacts the interaction between the entrapped water and the reverse micelle interface created with an ionic liquid-like surfactant

The behavior of the interfacial water entrapped in reverse micelles (RMs) formed by the ionic liquid-like surfactant 1-butyl-3-methylimidazolium 1,4-bis-2-ethylhexylsulfosuccinate (bmim-AOT) dissolved in benzene (or chlorobenzene) was investigated using noninvasive techniques such as dynamic light scattering (DLS), static light scattering (SLS), FT-IR and (1)H NMR. The DLS and SLS results reveal the formation of discrete spherical and non-interacting water droplets stabilized by the bmim-AOT surfactant. Moreover, since the droplet size increases as the W0 (W0 = [water]/[surfactant]) value increases, water interacts with the RM interface. From FT-IR and (1)H NMR data, a weaker water-surfactant interaction in bmim-AOT RMs in comparison with the RMs created by sodium 1,4-bis-2-ethylhexylsulfosuccinate (Na-AOT) is detected. Consequently, there are less water molecules interacting with the interface in bmim-AOT RMs, and their hydrogen bond network is not completely disrupted as they are in Na-AOT RMs. The results show how the nature of the new cation impacts the interaction between the entrapped water and the RM interface, modifying the interfacial water structure in comparison with the results known for Na-AOT.

Micellar dipole potential is sensitive to sphere-to-rod transition

Structural transitions involving shape changes play an important role in cellular physiology. Charged micelles offer a convenient model system in which structural transitions can be suitably induced by increasing the ionic strength of the medium. In this paper, we have explored sphere-to-rod transition in charged micelles of SDS and CTAB by monitoring micellar dipole potential using the dual wavelength ratiometric approach utilizing the potential-sensitive membrane probe di-8-ANEPPS. Our results show that micellar dipole potential is sensitive to sphere-to-rod transition in charged micelles. Micellar dipole potential exhibited increase with increasing ionic strength (salt), irrespective of the nature of micellar charge, implying considerable dipolar reorganization underlying structural transitions. We interpret the increase in dipole potential due to sphere-to-rod transition because of an increase in the population of confined (nonrandom) dipoles induced by micellar organizational change. This is due to the fact that dipole potential arises due to the nonrandom arrangement of micellar dipoles and water molecules at the micelle interface. Our results constitute one of the first reports describing drastic dipolar reorganization due to micellar shape (and size) change. We envision that dipole potential measurements could provide novel insights into micellar processes that are associated with dipolar reorganization.

The vesicle formation of β-CD and AD self-assembly of dumbbell-shaped amphiphilic triblock copolymer

Vesicles of a noncovalent dumbbell-shaped amphiphilic triblock copolymer were formed by self-assembly of host-guest inclusion between β-cyclodextrin containing poly(ethylene oxide) (β-CD-PEO) and adamantyl group containing polystyrene (AD-PS-AD) in solution. Addition of water into the copolymer resulted in the formation of new bowl-shaped and vesicle morphologies by adjusting not only ratio of solvents (THF dioxane or DMF) but also the length of the PS middle block in the guest polymer, which was ascribed to the large compound micelles (LCMs). The continuous phase of PS was composed of an assembly of reversed micelles (PEO core and PS corona) with hydrophilic PEO chains surrounding the structure at the polymer/aqueous solution interface in the larger compound micelles.

Interaction of quinine sulfate with anionic micelles of sodium dodecylsulfate: A time-resolved fluorescence spectroscopy at different pH

Photophysical behavior and rotational relaxation dynamics of quinine sulfate (QS) in anionic surfactant, sodium dodecylsulfate (SDS) at different pH have been studied using steady state and time resolved fluorescence spectroscopy. It has been observed that the cationic form of quinine sulfate (at pH 2) forms a fluorescent ion pair complex with the surfactant molecules at lower concentrations of surfactant. However, for higher concentrations of SDS, the probe molecules bind strongly with the micelles and reside at the water–micelle interface. At pH 7, QS is singly protonated in bulk aqueous solution. At lower concentrations of SDS aggregation between probe and surfactant molecules has been observed. However, for higher concentrations of SDS, an additional fluorescence peak corresponding to dicationic form of QS appears and this has been attributed to double protonation of the QS molecule in micellar solution. At pH 7, in the presence of SDS micelles, the photophysical properties of QS showed substantial changes compared to that in the bulk water solution. At pH 12, an increase in fluorescence intensity and lifetime has been observed and this has been attributed to the increase in radiative rate due to the incorporation of QS at the micelle–water interface. The local pH at micellar surface has been found different from the pH of bulk solution.

Mechanical properties of milk protein skin layers after drying: Understanding the mechanisms of particle formation from whey protein isolate and native phosphocaseinate

The spray drying of milk proteins usually leads to dry particles of which the final shape can influences physical and functional properties of powders. The aim of this study was to understand the mechanisms of particle formation by considering the mechanical properties of materials making up the two main classes of milk proteins: whey proteins and casein micelles. The progressive solidification of the interface of the droplet during drying time was studied by high speed camera and fluorescence microscopy, in different experimental conditions. The mechanical properties of the final protein materials were then characterized by micro indentation testing. The drying dynamics of whey protein and casein micelle droplets showed different timescales and mechanical lengths, whatever the drying conditions and the droplet configurations, leading to typical mechanical instability at the surface i.e. buckling and fracture. The interface of casein micelles reached sol–gel transition earlier estimated at around 156 g.L−1 following by elastic and plastic regimes in which the shell distorted and buckled to form a final wrinkled particle. In contrast, the interface of whey proteins became elastic at only half the drying time estimated at around 414 g.L−1, retaining a spherical shape, which finally fractured at the end of drying. The mechanical difference between the two plastic shells might be explained by the behaviour of proteins in jamming conditions. Analogous behaviour could be discussed between the casein micelles and soft and deformable colloids on the one hand, and between whey proteins and hard spheres on the other.

Stability of bacterial carotenoids in the presence of iron in a model of the gastric compartment – Comparison with dietary reference carotenoids

Recently isolated spore-forming pigmented marine bacteria, Bacillus indicus HU36 and Bacillus firmus GB1 are sources of carotenoids (∼fifteen distinct yellow and orange pigments and ∼thirteen distinct pink pigments, respectively). They are glycosides of oxygenated lycopene derivatives (apo-lycopenoids) and are assumed to be more heat- and gastric-stable than common carotenoids. In this study, the oxidation by O2 of the bacterial carotenoids was initiated by free iron (FeII and FeIII) or by heme iron (metmyoglobin) in a mildly acidic aqueous solution mimicking the gastro-intestinal compartment and compared to the oxidation of the common dietary carotenoids β-carotene, lycopene and astaxanthin. Under these conditions, all bacterial carotenoids appear more stable in the presence of heme iron vs. free iron. Carotenoid autoxidation initiated by FeII is relatively fast and likely involves reactive oxygen–iron species derived from FeII and O2. By contrast, the corresponding reaction with FeIII is kinetically blocked by the slow preliminary reduction of FeIII into FeII by the carotenoids. The stability of carotenoids toward autoxidation increases as follows: β-carotene<lycopene<astaxanthin<HU36 and GB1. In particular, bacterial carotenoids react more quickly than reference carotenoids with FeIII, but much more slowly than the reference carotenoids with FeII. This reaction is correlated with the structure of the carotenoids, which can have opposite effects in a micellar system: bacterial carotenoids with electro-attracting terminal groups have a lower reducing capacity than β-carotene and lycopene. However, their polar head favours their location close to the interface of micelles, in closer contact with oxidative species. Kinetic analyses of the iron-induced autoxidation of astaxanthin and HU36 carotenoids has been performed and gives insights in the underlying mechanisms.

Synthesis, Characterization and Aqueous Properties of a New Hybrid Fluorocarbon Cationic Surfmer

AbstractA novel hybrid fluorocarbon cationic surfmer has been synthesized and its aggregation and surface properties have been studied by surface tension, electrical conductivity, steady‐state fluorescence, Rayleigh light scattering, dynamic light scattering and transmission electron microscopy. Through surface tension, electrical conductivity, steady‐state fluorescence and Rayleigh light scattering measurements, the effectiveness of surface tension reduction, the maximum surface excess concentration, the minimum area occupied per surfactant molecule at the air/water interface, the micropolarity and aggregation number of micelles were investigated. The results shows that the surfmer has superior surface activity and lower micropolarity than other surfmers. The critical micelle concentration at different temperatures and a series of thermodynamic parameters (, , and , , , and ) of micellization were evaluated. The thermodynamic parameters showed that the micelle formation was entropy‐driven in the temperature range of 15–40 °C. The size and morphology of the aggregates were also confirmed by dynamic light scattering and transmission electron microscopy.

Differential contribution of tryptophans to the folding and stability of the attachment invasion locus transmembrane β-barrel from Yersinia pestis.

Attachment invasion locus (Ail) protein of Yersinia pestis is a crucial outer membrane protein for host invasion and determines bacterial survival within the host. Despite its importance in pathogenicity, surprisingly little is known on Ail biophysical properties. We investigate the contribution of micelle concentrations and interface tryptophans on the Ail β-barrel refolding and unfolding processes. Our results reveal that barrel folding is surprisingly independent of micelle amounts, but proceeds through an on-pathway intermediate that requires the interface W42 for cooperative barrel refolding. On the contrary, the unfolding event is strongly controlled by absolute micelle concentrations. We find that upon Trp→Phe substitution, protein stabilities follow the order W149F>WT>W42F for the refolding, and W42F>WT>W149F for unfolding. W42 confers cooperativity in barrel folding, and W149 clamps the post-folded barrel structure to its micelle environment. Our analyses reveal, for the first time, that interface tryptophan mutation can indeed render greater β-barrel stability. Furthermore, hysteresis in Ail stems from differential barrel-detergent interaction strengths in a micelle concentration-dependent manner, largely mediated by W149. The kinetically stabilized Ail β-barrel has strategically positioned tryptophans to balance efficient refolding and subsequent β-barrel stability, and may be evolutionarily chosen for optimal functioning of Ail during Yersinia pathogenesis.

Molecular dynamics study of the adsorption of anionic surfactant in a nonionic polymer brush

The adsorption of the anionic surfactant, sodium dodecylsulfate (SDS) in poly(ethylene oxide) (PEO) brush was studied by molecular dynamics simulations. Our simulations revealed that surfactant can adsorbin polymer brush as micellar aggregates and the polymer would reside at the hydrocarbon-water interface of SDS micelles. This association between surfactant and polymer was mainly driven by the hydrophobic interaction between the polymer and surfactant tails. In the simulation, with the increasing of surfactant concentration, a plateau value representing saturated adsorption was observed. The height of polymer brush was mainly affected by the adsorbed surfactant at low grafting density of polymer; however, it was primarily controlled by the grafting density at high grafting density. Our conclusions at the molecular level were in close agreement with experiment about the adsorption of surfactant in polymer brushes.

Dynamics of pyrenesemicarbazide and pyrenethiosemicarbazide in reverse micelle of AOT in n-heptane: Probing critical penetration of water molecules toward the palisade

In the present work, we have introduced two similar probe molecules with pyrene tags that can reside in different positions in the reverse micelles and show opposite dynamism on excitation. Herein, we have changed the concentration of water in the reverse micellar core gradually and monitored the spectrochemical changes in the dynamism of the two designed probe molecules. The results indicate that water molecules penetrate through the interface of the reverse micelles up a certain critical amount.

Dielectric Relaxation Spectroscopy Shows a Sparingly Hydrated Interface and Low Counterion Mobility in Triflate Micelles

The properties of ionic micelles are affected by the nature of the counterion. Specific ion effects can be dramatic, inducing even shape and phase changes in micellar solutions, transitions apparently related to micellar hydration and counterion binding at the micellar interface. Thus, determining the hydration and dynamics of ions in micellar systems capable of undergoing such transitions is a crucial step in understanding shape and phase changes. For cationic micelles, such transitions are common with large organic anions as counterions. Interestingly, however, phase separation also occurs for dodecyltrimethylammonium triflate (DTATf) micelles in the presence of sodium triflate (NaTf). Specific ion effects for micellar solutions of dodecyltrimethylammonium chloride (DTAC), bromide (DTAB), methanesulfonate (DTAMs), and triflate (DTATf) were studied with dielectric relaxation spectroscopy (DRS), a technique capable of monitoring hydration and counterion dynamics of micellar aggregates. In comparison to DTAB, DTAC, and DTAMs, DTATf micelles were found to be considerably less hydrated and showed reduced counterion mobility at the micellar interface. The obtained DTATf and DTAMs data support the reported central role of the anion's -CF3 moiety with respect to the properties of DTATf micelles. The reduced hydration observed for DTATf micelles was rationalized in terms of the higher packing of this surfactant compared to that of other DTA-based systems. The decreased mobility of Tf(-) anions condensed at the DTATf interface strongly suggests the insertion of Tf(-) in the micellar interface, which is apparently driven by the strong hydrophobicity of -CF3.

Self-Aggregation of MEGA-9 (N-Nonanoyl-N-methyl-d-glucamine) in Aqueous Medium: Physicochemistry of Interfacial and Solution Behaviors with Special Reference to Formation Energetics and Micelle Microenvironment

Self-aggregation of MEGA-9 (N-nonanoyl-N-methyl-D-glucamine), a nonionic sugar-based surfactant, was studied with respect to the effect of salt (NaCl) and ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate) on its critical micelle concentration (cmc), aggregation number, hydrodynamic dimensions, energetics of micellization, and micellar microenvironment. Fluorimetry (both steady state and time resolved) was used to understand the microenvironments under the influence of additives. NaCl was found to decrease cmc, increase aggregation number (N), increase micellar size, and decrease enthalpy of micelle formation; the IL effect on the parameters was mostly opposite. The microscopic properties of micelles were probed using two fluorophores: one nonpolar C-153 (2,3,5,6-1H,4H-tetrahydro-8-trifluormethylquinolizino-(9,9a,1-gh)coumarin) and the other fairly polar ANS (8-anilinonaphthalene-1-sulfonate); they delivered information on the palisade layer and the peripheral region of the micelle interface, respectively. Energy of activation and entropy of activation of the dynamics of the probes were evaluated from their decay time, lifetime, and rotational movements in the regions of residency in the micelles. Density functional theory (DFT) calculations showed that the ternary combination MEGA-9/IL/H2O had the maximum interaction energy compared to any of the binary combinations. Thus, the ionic liquid reduced MEGA-9 self-association to a large extent.

Effect of Counterions on the Shape, Hydration, and Degree of Order at the Interface of Cationic Micelles: The Triflate Case

Specific ion effects in surfactant solutions affect the properties of micelles. Dodecyltrimethylammonium chloride (DTAC), bromide (DTAB), and methanesulfonate (DTAMs) micelles are typically spherical, but some organic anions can induce shape or phase transitions in DTA(+) micelles. Above a defined concentration, sodium triflate (NaTf) induces a phase separation in dodecyltrimethylammonium triflate (DTATf) micelles, a phenomenon rarely observed in cationic micelles. This unexpected behavior of the DTATf/NaTf system suggests that DTATf aggregates have unusual properties. The structural properties of DTATf micelles were analyzed by time-resolved fluorescence quenching, small-angle X-ray scattering, nuclear magnetic resonance, and electron paramagnetic resonance and compared with those of DTAC, DTAB, and DTAMs micelles. Compared to the other micelle types, the DTATf micelles had a higher average number of monomers per aggregate, an uncommon disk-like shape, smaller interfacial hydration, and restricted monomer chain mobility. Molecular dynamic simulations supported these observations. Even small water-soluble salts can profoundly affect micellar properties; our data demonstrate that the -CF3 group in Tf(-) was directly responsible for the observed shape changes by decreasing interfacial hydration and increasing the degree of order of the surfactant chains in the DTATf micelles.

Counterion Affects Interaction with Interfaces: The Antidiabetic Drugs Metformin and Decavanadate

AbstractA material that contains metformium cation and decavanadate anion was synthesized and characterized. The material is not soluble in water but slightly soluble in dimethyl sulfoxide and very soluble in the inhomogeneous environment of sodium bis(2‐ethylhexyl)sulfosuccinate (AOT) reverse micelles, which deviates significantly from the properties of sodium decavanadate. By considering the fact that decavanadate is reported to have insulin‐enhancing activity in streptozotocin (STZ)‐induced diabetic rats (Pereira et al., J. Inorg. Biochem. 2009, 103, 1687–1692), how this oxometalate interacts with interfaces was investigated using NMR and IR spectroscopy. By using 51V NMR spectroscopy, we found only small differences between the metformium and Na+ decavanadate materials. However, by using IR spectroscopy, the decavanadate–metformin material was found to affect the water pool and water organization near the interface of the reverse micelles differently. The solubility differences and these spectroscopic studies demonstrate that the counterion to the decavanadate anion significantly affects the properties of decavanadate, even in the presence of a large excess amount of Na+ (counterions to AOT), and the implications of this work on cellular uptake is discussed.

PRODAN Dual Emission Feature To Monitor BHDC Interfacial Properties Changes with the External Organic Solvent Composition

We have investigated the water/benzyl-n-hexadecyldimethylammonium chloride (BHDC)/n-heptane:benzene reverse micelles (RMs) interfaces properties using 6-propionyl-2-(N,N-dimethyl)aminonaphthalene, PRODAN, as molecular probe. We have used absorption and emission (steady-state and time-resolved) spectroscopy of PRODAN to monitor the changes in the RMs interface functionalities upon changing the external organic solvent blend. We demonstrate that PRODAN is a useful probe to investigate how the external solvent composition affects the micelle interface properties. Our results show that changes in the organic solvent composition in water/BHDC/n-heptane:benzene RMs have a dramatic effect on the photophysics of PRODAN. Thus, increasing the aliphatic solvent content over the aromatic one produces PRODAN partition and PRODAN intramolecular electron transfer (ICT) processes. Additionally, the water presence in these RMs makes the PRODAN ICT process favored with the consequent decreases in the LE emission intensity and a better definition of the charge transfer (CT) band. All this evidence suggests that the benzene molecules are expelled out of the interface, and the water-BHDC interactions are stronger with more presence of water molecules in the polar part of the interface. Thus, we demonstrate that a simple change in the composition of the external phase promotes remarkable changes in the RMs interface. Finally, the results obtained with PRODAN together with those reported in a previous work in our lab reveal that the external phase is important when trying to control the properties of RMs interface. It should be noted that the external phase itself, besides the surfactant and the polar solvent sequestrated, is a very important control variable that can play a key role if we consider smart application of these RMs systems.