Double-chain Cationic Surfactant Research Articles

Interaction of double-chained cationic surfactants, dimethyldialkylammoniums, with erythrocyte membranes: stabilization of the cationic vesicles by phosphatidylcholines with unsaturated fatty acyl chains.

We studied the interaction of double-chained cationic surfactants, dimethyldialkylammoniums, (CH3)2N+(CnH2n+1)2, with the lipid bilayer of guinea-pig erythrocytes by observing the haemolysis, aggregation and shape change in the erythrocytes. In the presence of sonicated dispersions of the five dimethyldialkylammoniums tested (n = 10, 12, 14, 16 and 18), haemolysis was induced dose dependently, and at 0.1 mM or higher concentrations, haemolysis was induced more rapidly by dimethyldialkylammoniums with shorter alkyl chains. The cationic surfactants with longer alkyl chains, such as dimethyldipalmitylammonium, induced aggregation of the erythrocytes before haemolysis fully progressed. The vesicles of these long-chain dimethyldialkylammoniums in the presence of phosphatidylcholines with unsaturated fatty acyl chains markedly reduced the haemolysis rates. Furthermore, in the presence of phosphatidylcholines with unsaturated acyl chains the formation of tightly aggregated structures of several erythrocytes was observed. These findings, and analysis by spin label 5-doxylstearic acid, indicate that phosphatidylcholines enriched with unsaturated acyl chains stabilize the cationic vesicles of long-chain dimethyldialkylammoniums and the interaction with the lipid bilayer of erythrocyte membranes as cationic vesicles became prominent.

Lubrication in Aqueous Solutions Using Cationic Surfactants − a Study of Static and Dynamic Forces

This paper concerns lubrication in aqueous surfactant systems where the surfactants adsorb at surfaces, in relative motion, forming either a surfactant monolayer or a multi- (liquid crystalline) layer. The surfactants were of two kinds, viz., a double chain cationic surfactant, didodecyldimethylammonium bromide, DDAB, and a single chain cationic surfactant, dodecyltrimethylammonium bromide, DTAB. Excellent film forming capability was shown for DDAB and interpreted as the result of good packing of the surfactant molecules at the surfaces, i.e., the inherent ability of the surfactant molecules to form liquid crystalline structures at the surface, resulting in good load-carrying capability. This is also reflected in the bulk properties of the surfactants, where DDAB show lamellar liquid crystalline phases at concentrations much lower than DTAB, which does not show good lubrication properties. The results are discussed in terms of film stability of a surfactant layer adsorbed at the surface, which in turn is correlated to the critical packing parameter of the surfactant, in analogy with the Kabalnov?Wennerstrom theory of emulsion droplet coalescence (Kabalnov, A.; Wennerstrom, H. Langmuir 1996, 12, 276). The systems were characterized using (i) the surface force apparatus determining the interaction forces between the adsorbed layers at the surfaces and (ii) the EHD rig (elastohydrodynamic rig) determining film formation under shear. The adsorption kinetics and composition at the surface were determined by a quartz crystal microbalance and X-ray photoelectron spectroscopy

Enhancement effects of double-chained cationic surfactants of n-dimethyldialkylammoniums on permeability of salicylate through guinea pig dorsal skin.

We examined the enhancement effects of the double-chained cationic surfactants of n-dimethyldialkylammoniums (CH(3))(2)N(+)(C(n)H(2n+1))(2) on the permeation of anionic salicylate through excised guinea pig dorsal skin at pH 7.4. Among them, n-dimethyldidecylammonium (2C10), which seemed to form micelles, had dose-dependent enhancement effects at concentrations of more than 0.1 mM, and about a ninety-fold increase in the permeability coefficient of salicylate was observed at 2 mM. The enhancement effect of 2C10 was larger than those of single-chained cationic surfactants of n-alkyltrimethylammoniums. n-Dimethyldilaurylammonium (2C12), which seemed to form bilayer vesicles, induced about a twenty five-fold increase in the permeability coefficient. The enhancement effects of n-dimethyldialkylammoniums decreased with the increase in their alkyl chain lengths. In contrast, only slight stimulation by these cationic surfactants was observed for silicon rubber membrane permeation of salicylate. Analysis of the retention of the salicylate in the skin suggested that the double-chained cationic surfactants-induced increase in the transfer of salicylate to the skin is the main reason for the marked stimulation of the skin permeation.

Vesicles Formation of Double-Chain Cationic Surfactants with Different Chain-Lengths in Deep Sea Water.

Vesicles Formation of Double-Chain Cationic Surfactants with Different Chain-Lengths in Deep Sea Water.

Thermodynamics of Molecular Self-Assembly of Two Series of Double-Chain Singly Charged Cationic Surfactants

Microcalorimetric measurements have been made as a function of temperature on the series of double-chain cationic surfactants consisting of a dimethylammonium headgroup attached to alkyl chains of different lengths, CM and CN, giving the formula CMH2M+1CNH2N+1N(CH3)2Br. We have studied compounds with two values of M, 12 and 14, and values of N equal to 1, 2, 4, 6, 8, 10, etc., which we designate by the simpler formula CMCNDAB. In both series, the magnitudes of the values of ΔHmic pass through a negative minimum at N = 4−6. At room temperature, this results in the compounds with M = 12 and N = 4 and 6 having endothermic enthalpies of micellization. All the other values measured were exothermic. This minimum in ΔHmic at N = 4−6 is more than compensated by the behavior of the entropy of micellization, to the extent that no abnormal variation of cmc down the series is observed. Thus, as found for the geminis, simple measurements of ΔGmic via the cmc conceal more interesting variations in ΔHmic and ΔSmic. The values of ΔCP,m for both series were first reported in this work, and they were all found to be negative. The results show that the values of ΔCP,m for the C14CNDAB series have a marked minimum but those for the C12CNDAB just have a weak minimum with N.

Double-chained surfactants for semipermanent wall coatings in capillary electrophoresis

The double-chained cationic surfactant didodecyldimethylammonium bromide (DDAB) was found to form more stable coatings onto the walls of CE capillaries than similar single-chained surfactants such as cetyltrimethylammonium bromide (C16TAB). After removing DDAB from the buffer, the reversed EOF decreased only 3% over 75 min under continuous electrophoretic conditions. Also, the reversed EOF is 60% greater for DDAB than for C16TAB at pH 2. This greater coating stability is associated with a different aggregate structure for the surfactant at the capillary surface. The more homogeneous coating and greater surface coverage provided by DDAB allows the excess surfactant to be flushed from the capillary prior to performing electrophoretic separations. Separations of a basic protein mixture yielded quantitative recoveries, efficiencies ranging from 560,000 to 750,000 plates/m, and migration time reproducibility of 0.8-1.0% RSD (n = 10). This performance is similar to that of adsorbed cationic polymers (Polybrene, polyethyleneimine) but is achieved using a coating procedure that is over 10 times faster.

A Small-Angle Neutron Scattering Study of Surfactant Aggregates Formed in Aqueous Mixtures of Sodium Dodecyl Sulfate and Didodecyldimethylammonium Bromide

The structure of aggregates formed in aqueous mixtures of a single-chain anionic surfactant, sodium dodecyl sulfate (SDS), and a double-chain cationic surfactant, didodecyldimethylammonium bromide (DDAB), has been investigated at 38 °C using small-angle neutron scattering (SANS). Several overall surfactant concentrations [SDS] + [DDAB] between 0.1 and 5 wt % were measured at the two SDS-rich compositions [SDS]:[DDAB] = 90:10 and 95:5. Samples with a concentration above about [SDS] + [DDAB] = 1 wt % at [SDS]:[DDAB] = 95:5 contained only somewhat elongated tablet-shaped micelles (triaxial ellipsoids) with typical values of the half-axes a (related to the thickness) = 14 A, b (related to the width) = 23 A, and c (related to the length) = 27 A. When a sample at [SDS]:[DDAB] = 95:5 is diluted below about [SDS] + [DDAB] = 1 wt %, an increasing amount of small unilamellar vesicles forms, and in the samples below about 0.2 wt %, only vesicles are observed. The average radius of the vesicles 〈R〉 increases from abo...

Phase and aggregation behaviour of double-chain cationic surfactants from the class of N -alkyl- N -alkyl?- N , N -dimethylammonium bromide surfactants

We present the phase diagrams and the properties of newly synthesised double-chain cationic N-alkyl-N-alkyl′-N,N-dimethylammonium bromide surfactants [CxCyDMABr (x = 12, 14 and 16; y = 10, 11, 12, 14 and 16)]. All the systems studied form liquid-crystalline lamellar phases but with different morphologies: unilamellar vesicles at low surfactant concentrations, multilamellar vesicles and tubular aggregates for surfactant concentrations between 2 and 10 wt% and at even higher concentrations planar bilayers of surfactant molecules in the classical Lα phase. The phase diagrams were determined with macroscopic and microscopic methods (polarisation microscopy, freeze-fracture transmission electron microscopy, scanning electron microscopy and differential interference contrast microscopy). The properties of the surfactant solutions were determined with differential scanning calorimetry measurements for Krafft point determination and small-angle neutron scattering measurements for interlamellar spacing and bilayer thickness. Finally, conductivity and viscosity measurements for phase characterisation were carried out.

Equation of state of a charged bilayer system: Measure of the entropy of the lamellar–lamellar transition in DDABr

The synthetic cationic double-chain surfactant didodecyldimethylammonium bromide shows two distinct thermodynamically stable lamellar phases; a dilute Lα phase stabilized predominantly by electrostatic forces, and a condensed Lα′ phase stabilized by “hydration” forces. Using six different experimental methods, applying osmotic stress from 102 to 109 Pa and varying temperature from 20 °C to 70 °C, we have measured the osmotic pressure vs interbilayer distance and thus mapped the phase diagram with an equation of state. In this binary system, the area per headgroup as well as bilayer thickness vary with concentration and temperature. Hence, lateral compressibility has to be taken into account in the free energy balance. The osmotic stress needed to effect the swollen-to-collapsed lamellar phase transition is determined as a function of temperature. From these data the entropy of the Lα–Lα′ transition is found to be a strong function of temperature. Below 40 °C, condensation from the dilute Lα phase, the change of entropy is negative as might be expected. Above 40 °C the entropy of condensation is positive, demonstrating that there is a release of degrees of freedom associated with the bilayer condensation. These data allow us to think far more critically about the forces that stabilize bilayer systems.

アルキル鎖長の異なる二鎖型力チオン界面活性剤ベシクルによる芳香族化合物の可溶化

アルキル鎖長の異なる二鎖型カチオン界面活性剤 (ジドデシルジメチルアンモニウムプロミド;DDAB, ジテトラデシルジメチルアンモニウムプロミド;DTDAB, ジヘキサデシルジメチルアンモニウムプロミド;DHDAB) ベシクルによる芳香族化合物の可溶化を, 平衡透析法, 蛍光プローブ法, 動的光散乱法により検討した。その結果, 調製したべシクルの粒子径はアルキル鎖長の増加に伴い増大した。また, 親水基を有する油性物質である3-フェニルプロピオン酸 (HCA) の可溶化平衡定数 (K) は, 界面活性剤のアルキル鎖長の増加に伴い著しく増加し, ベシクル内における界面活性剤分子と油性物質分子との相互作用は界面活性剤のアルキル鎖長の増加に伴い増加することが分かった。しかし, 疎水性の強い油性物質であるエチルベンゼン (EB) を用いた場合には, そのK値に大きな増加は認められなかった。さらに, DDABベシクルの静置安定性は優れているが, DTDAB, DHDABベシクルの静置安定性は悪いことが分かった。

Conductivity and dynamic light scattering studies on homologous alkylbenzyldimethylammonium chlorides in aqueous solutions

The critical micelle concentration and ionization degree of micelles formed by decyl-, dodecyl- and tetradecylbenzyldimethylammonium chlorides in aqueous solutions at 298 K have been determined conductometrically. The hydrodynamic radii of the micelles have been estimated from quasi-elastic light scattering data obtained for the surfactants in aqueous sodium chloride solutions. Both techniques yield results indicating a high degree of ionization of the micelles, suggesting that the benzyl group acts as a second hydrophobic substituent at the head group of the surfactant and plays a role similar to that of a second alkyl chain in double-chained cationic surfactants.

Crossflow microfiltration behaviour of a double-chain cationic surfactant dispersion in water—I. The effect of process and membrane characteristics on permeate flux and surfactant rejection

Microfiltration of a double-chain cationic surfactant, dioctadecyldimethylammonium chloride, in water has been studied using 1 or 0.2 μm track-etched polycarbonate membranes. A computer-controlled filter rig was used, in which the process conditions of crossflow velocity u, transmembrane pressure drop Δ p and temperature T were changed independently. In addition, permeate flux J and in some cases surfactant concentration in the feed c f and permeate c p , were monitored during filtration. The effects of process and material variables on the permeate flux decay, steady-state permeate flux J ∞ and the permeate surfactant concentration were assessed. It was found that fouling of the membrane by surfactant is very rapid (within tens of seconds) although high crossflow veclocity, large memebrane pore size and low feed surfactant concentration reduced the rate of surfactant deposition. Steay-state permeate flux increases significantly with crossflow velocity provided the surfactant is in a rigid chain (gel) lamellar dispersion state ( T < 48°C). The steady-state permeate flux J ∞ decays linearly with ln ( c f ) provided the feed concentration is less than the so-called gel concentration ( c g ) which is obtained by extrapolating the linear portion of the curves J ∞ vs ln ( c f ) so that c f = c g when J ∞ 0. Although the gel concentration, which is independent of pore size and the process variables, is found to be 20 gl −1, experiments conducted at feed concentration well above c g still yield a reasonable permeate flux, albeit at a reduced level. Surfactant rejection studies indicate that 0.2 μm membranes yield lower rejection than 1 μm membranes while rejection is greater at 30°C than at 60°C. Other process variables do not have any significant influence on rejection. The effectiveness of a membrane and the processing conditions can be quantified by considering the variation of J ∞ with c p/c f . It is found that a 1 μm membrane is more effective than a 0.2 μm membrane, crossflow velocity increase the effectiveness of the process, and that temperature has no significant influence.

Characterization of the complexes of amphiphilic polyanions and double-chain cationic surfactants

Coulombic complexes of amphiphilic polyanions and double-chain cationic surfactants were prepared by adding an aqueous solution of didodecyldimethylammoniumbromide (DDAB) to aqueous solutions of terpolymers consisting of sodium 2-(acrylamido)-2-methylpropanesulfonate, N-(1-adamantyl)methacrylamide (49 mol%) or N-(1-naphthylmethyl)methacrylamide (59 mol%), and N-(1-pyrenylmethyl)-methacrylamide (1 mol%)

Preparation and characterisation of polymerised proteovesicles

The cationic double-chain surfactant, hexadecyl[11-(methacryloyloxy)undecyl] ammonium bromide in combination with dipalmitoylphosphatidylethanolamine (DPPE) derivatised with maleimidobenzyl- N-hydroxysuccinimide (MBS) has been used to make polymerisable vesicles which can be conjugated with a protein (lysozyme) to form polymerised proteovesicles. Polymerisation was carried out at room temperature using Fenton's reagent (hydrogen peroxide and ferrous ions). It was found that unpolymerised proteovesicles can be prepared by this procedure but such pre-formed proteovesicles cannot be polymerised without initiating precipitation; however if polymerisation precedes protein conjugation, proteovesicles can be prepared in the dispersed state. In contrast to unpolymerised proteovesicles, polymerised proteovesicles form small aggregates in solution together with physically adsorbed lysozyme, suggesting that the rigidity of the underlying vesicle bilayers significantly influences the physical adsorption process.

The polymerisation of methacryloyl surfactant vesicles by Fenton's reagent and their characterisation and stability to alcohol and detergents

The cationic double chain surfactant hexadecyl [11-(methacryloyloxy) undecyl] ammonium bromide (methacryloyl surfactant) has been used to make polymerisable vesicles in aqueous solution. Polymerisation was initiated using Fenton's reagent (hydrogen peroxide and ferrous ions) at room temperature. Fenton's reagent is shown to give vesicles with a very high degree of polymerisation, as by the loss of olefinic hydrogen atoms by proton NMR spectroscopy, over a wide range of experimental conditions (hydrogen peroxide to ferrous ion and surfactant to hydrogen peroxide molar ratios). The polymerised vesicles ranged in size (peak diameter of the equivalent normal weight distribution) from 120 to 260 nm as measured by photon correlation spectroscopy. The stability of the vesicles to disruption by ethanol and the non-ionic detergents Triton X-100 and octyl glucoside was investigated from absorbance and size measurements. It has been found that for both unpolymerised and polymerised surfactant vesicles the optical absorbance curves at 400 nm pass through maxima as a function of the concentration of additive. For polymerised vesicles the absorbance maxima are broader and sufficiently different from those of unpolymerised vesicles to be used as a diagnostic test for polymerisation. The origin of the absorbance behaviour is discussed in terms of vesicle fusion/aggregation and disruption.

The flotation of quartz using a double-chained cationic surfactant

The froth flotation of ground quartz and ballotini glass spheres using the collector dihexadecyldimethylammonium acetate (DHDAA) was examined using a Hallimond tube. Large differences in the flotation properties of these two give further support to the proposition by Anfruns and Kitchener that surface roughness is an important factor in flotation ( Trans. Inst. Min. Metall. 86, 9 (1977)). These results led to the study of an unusual cosurfactant, methyltrihexylammonium bromide which was specifically chosen to adsorb preferentially onto angular regions of quartz particles. This cosurfactant markedly increased the flotation efficiency of quartz in DHDAA solutions. In addition, the observation that the adsorption of DHDAA at the air/water interface is a slow process has been used to show that adsorption of surfactant at the bubble surface is not an important factor in the flotation of rough ground particles.

Forces between mica surfaces in dilute solutions of a double-chained quaternary ammonium ion surfactant

Measurements are reported here on the interaction between adsorbed monolayers and bilayers of a double-chained cationic surfactant on mica. Two adsorption procedures were used which produced different characteristics. Sequential adsorption produced an intercalated monolayer exhibiting low adhesion whereas direct adsorption produced a hydrophobic monolayer. Bilayer adsorption occurred at much higher concentrations that where aggregation in bulk solution seems to occur. The Debye length of these solutions has also been measured and appears to approximate to counterion-only screening and provides insight into the use of this parameter to characterize electrostatic interactions in surfactant solutions.

Remarkable Steric Control for the Enantioselective Cleavage of Amino Acid Esters

Abstract The perfect enantioselective catalysis was observed for the hydrolytic cleavage of p-nitrophenyl N-dodecanoyl-d(l)-phenylalaninates by N-benzyloxycarbonyl-l-phenylalanyl-l-histidyl-l-leucine in specific co-aggregates composed of a cationic doublechain surfactant and a cationic, an anionic, or a nonionic single-chain surfactant.

Enantioselectivity Enhancement in the Deacylation of N-Acyl Amino Acid Esters by Vesicular Systems of Long Chain Dipeptide Nucleophiles and a Cationic Double Chain Surfactant

Abstract The enantioselective deacylation of short chain and long chain N-acyl amino acid p-nitrophenyl esters, CH3(CH2)nCONH\overset*CH(R)–CO2C6H4NO2-p (R=C6H5CH2, (CH3)2CHCH2, CH3; n=0, 8, 12), was carried out at 4–25°C (pH 7.68) with the vesicular systems composed of N,N-didodecyl-N,Ndimethylammonium bromide and long chain nucleophiles, Nα-dodecanoyl-l-histidine, Nα-(N-dodecanoyl-l-leucyl)-l-histidine(3a), Nα-(N-dodecanoyl-l-phenylalanyl)-l-histidine (3b), and N-(Nα-dodecanoyl-l-histidyl)-l-leucine (3c). Both the deacylation rate and the enantioselectivity were the largest in the deacylation of the substrates possessing a long N-acyl chain (n=8) with the efficient dipeptide nucleophiles (3a and 3b) including the l-histidine moiety in their terminal position, and the neighboring amino acid binding to the l-histidine in 3a, 3b, and/or 3c was found to play an important role in the enhancement of enantioselectivity. The lowering of the reaction temperature decreased the deacylation rate and increased the enantioselectivity. The maximum enantiomer rate ratio of 24.5 was obtained in the deacylation of p-nitrophenyl N-dodecanoylphenylalaninates with the dipeptide nucleophile 3b. The characteristic features of the present reaction are discussed on the basis of kinetic parameters (binding constants and activation parameters) and isokinetic relationships.

High stereoselectivity in the deacylation of p-nitrophenyl N-acylphenylalanates by bilayer vesicular systems which include dipeptide-type nucleophiles

The deacylation of p-nitrophenyl N-acylphenylalanated with bilayer vesicular systems comprising dipeptide-type nucleophiles and a cationic double chain surfactant resulted in high stereoselectivity (kcatL/kcatD= 29.6 at 25 °C and 83.6 at 10 °C) for the deacylation of p-nitrophenyl N-dodecanoylphenylalanate by the catalytic system of N-(N-benzyloxycarbonyl-L-leucyl)-L-histidine and N,N-didodecyl-N,N-dimethylammonium bromide.