Single-chain Surfactants Research Articles

Cationic gemini surfactants with cleavable spacer: Chemical hydrolysis, biodegradation, and toxicity

The paper describes synthesis and characterization of a new type of cationic gemini surfactant, which has dodecyl tails and a spacer that contains an ester bond. The nomenclature used to describe the structure is 12Q2OCO1Q12, with Q being a quaternary ammonium group and the numbers indicating the number of methylene or methyl groups. Due to the close proximity to the two quaternary ammonium groups, the ester bond is very stable on the acid side and very labile already at slightly alkaline conditions. The hydrolysis products are two single chain surfactants (i.e. 12Q2OH and 12Q1COOH) which are less surface active than the intact gemini surfactant. 12Q2OCO1Q12 was found to be readily biodegradable, i.e. it gave more than 60% biodegradation after 28days. This is interesting because similar gemini surfactants but with ester bonds in the tails instead of the spacer, have previously been found not to be readily biodegradable. The gemini surfactant was found to be toxic to aquatic organisms (ErC50 value of 0.27mg/l), although less toxic than the two hydrolysis products.

Cationic vesicles of a carnitine-derived single-tailed surfactant: Physicochemical characterization and evaluation of in vitro gene transfection efficiency

Spontaneous vesicle formation in water by single-chain surfactants is rare. Here we show that in aqueous solution, a single-chain cationic surfactant 3-(dodecylcarbamoyl-2-hydroxypropyl)-trimethylammonium chloride (C12-CAR) derived from d,l-carnitine spontaneously forms vesicles with hydrodynamic diameters in the range of 30–70nm. A detailed self-assembly study of the C12-CAR surfactant was performed for the first time by use of a combination of techniques, including surface tension, conductivity, fluorescence probe, dynamic light scattering and transmission electron microscopy. The cationic surfactant was found to have a reasonably low critical aggregation concentration (3.4±0.2mM) in water at 298K. The vesicles were observed to be stable at the physiological temperature (310K) over a long period of time. Although the vesicles formed were found to be unstable and exhibit vesicle-to-tubule transition in the presence of salt, in the presence of 10mol% cholesterol the stability of vesicles is enhanced. When compared with lipofectamine-2000, the C12-CAR was found to act as an effective gene transfection agent in COS-1 cell line. The surfactant-DNA complex was also found to be nontoxic toward CHO cells.

Synthesis of organic rectorite with novel Gemini surfactants for copper removal

Three novel Gemini surfactants were used to prepare organic rectorite (OREC) under microwave irradiation, in comparison with single-chain surfactant ester quaternary ammonium salt (EQAS) and cetyltrimethyl ammonium bromide (CTAB). The structure and morphology of OREC were characterized by XRD, BET, FT-IR, TEM and TGA. The removal of Cu2+ on OREC from aqueous solution was performed. The results reveal that Gemini surfactants modified REC had larger interlayer distance and higher surface area than single-chain surfactants EQAS and CTAB, and the increasing amount or chain length of Gemini surfactants led to larger layer spacing and higher adsorption capacities. The adsorption behavior of Gemini surfactant modified REC can be better described by Freundlich adsorption isotherm model, with a maximum adsorption capacity of 15.16mgg−1. The desorption and regeneration experiments indicate good reuse property of Gemini modified REC adsorbent. Therefore, this study may widen the utilization of Gemini surfactants modified layered silicates.

Vesicle formation between single-chained cationic surfactant and plasmid DNA and its application in cell transfection

In the present study, we found that plasmid DNA could induce single-chained cationic surfactants cetyltrimethylammonium bromide (CTAB), dodecyltrimethylammonium bromide (DTAB), and dodecyltriethyl ammonium bromide (DEAB) to form vesicles once its concentration reached a critical value. Moreover, the gene for follicle-stimulating hormone was delivered into cells with these single-chained cationic surfactant/DNA vesicles and the transfection efficiency was comparable to that with lipofectamine™ 2000, a famous and widely used commercial transfection reagent, and also to that using electroporation method, although it was generally thought conventional single-chained cationic surfactant was not suitable for gene transfer. The conventional single-chained cationic surfactant is very cheap and stable and the vesicles are very easy to be prepared. Thereby, this study may suggest that the vesicles formed between plasmid DNA and surfactant should be prospective to transfer DNA.

Study of the Influence of Gemini Cationic Surfactants on the Dyeing and Fastness Properties of Polyester Fabrics Using Naphthalimide Dyes

AbstractIn this paper, the dyeing and fastness properties of three monoazo naphthalimide dyes including different imide groups (dye 1: ethyl amine, dye 2: ethyl glycinate and dye 3: glycine) on a polyester fabric were investigated in the presence of two gemini cationic surfactants (symbolized as 12‐4‐12 or 14‐4‐14) and a conventional single chain surfactant, dodecyltrimethylammonium bromide (DTAB). The color strength (K/S) of naphthalimide dyes on polyester fabric was measured through the reflectance spectrophotometric method, and the values obtained in the presence of different cationic surfactants increased in the order of dye 3 < dye 2 < dye 1. Although the K/S values indicated that the gemini cationic surfactants had almost no effect on the dyeing behavior of dye 1, but they were effective in dyeing ability of dye 2 and dye 3. The data for dye 2 demonstrated that build up of polyester fabrics in the presence of gemini surfactants are more than the conventional cationic surfactant, and also K/S values of dye 3 on polyester fabrics were in the order: DTAB > 12‐4‐12 > 14‐4‐14. It was found that the washing and rubbing fastness properties improved with increasing the concentration of surfactants. In addition, the sublimation fastness of dye 3 was more than the other dyes owing to the presence of a polar group in its chemical structure, and the light fastness of naphthalimide dyes on polyester fabrics was generally moderate.

Physicochemical investigations on the interactions between Gemini/single-chain cationic surfactants and bovine serum albumin

The interactions of Gemini surfactants 1-dodecyl-N,N′-[(1,4-dioxo-1,4-butanediyl)bis(oxy-2,1-ethanediyl)]bis[N,N′-dimethylammonium]dibromide (12-su-12) and 1-dodecyl-N,N′-[((2E)-1,4-dioxo-2-butene-1,4-diyl)bis(oxy-2,1-ethanediyl)]bis[N,N′-dimethylammonium]dibromide (12-fo-12) and the corresponding single-chain surfactant 1-dodecyl-N-[2-(acetyloxy)ethyl]-N,N-dimethyl ammonium bromide (DTAAB) with bovine serum albumin (BSA) were investigated by conductometry, fluorimetry, UV–vis and CD spectrometry, and dynamic light scattering. It was found that the bindings of all three surfactants to BSA were cooperatively driven by electrostatic and hydrophobic interactions. The Gemini surfactants, carrying more charges and hydrophobic tails, showed stronger interactions with BSA than the single-chain surfactant. The presence of the double bond in the spacer of 12-fo-12 enhanced the interaction between the surfactant and BSA and also significantly varied the binding sites as compared to 12-su-12 and DTAAB, which indicated an important role of the property of the spacer in the interaction between the surfactant and BSA.

Micellization of anionic gemini surfactants and their interaction with polyacrylamide

A series of anionic gemini surfactants have been synthesized. The surface properties and micellization process of as-prepared sulfonate gemini surfactants (SGS) and carboxylate gemini surfactant (CGS) have been studied by surface tension measurement and isothermal titration microcalorimetry. Meanwhile, the interaction of these five surfactants with polyacrylamide (PAM) was investigated using surface tension, steady-state fluorescence measurement, and isothermal titration microcalorimetry. The results show that the critical micelle concentrations (CMCs) of above-mentioned surfactants are more than 1 order of magnitude lower than those of corresponding single chain surfactants. Moreover, the enthalpy of micelle formation (ΔH mic) for the investigated gemini surfactants is negative. In the surfactant–PAM systems, the thermodynamic parameters of binding have also been determined. The conclusion may be drawn that the binding strength of SGS onto PAM is stronger than that of CGS, resulting from more compact structure of SGS aggregates. With increasing surfactant hydrophobicity, the values of ΔH agg become more exothermic and a ΔS agg decrease was observed. Therefore, the interaction between SGS and PAM is enthalpy-driven.

Biomechanics and thermodynamics of nanoparticle interactions with plasma and endosomal membrane lipids in cellular uptake and endosomal escape.

To be effective for cytoplasmic delivery of therapeutics, nanoparticles (NPs) taken up via endocytic pathways must efficiently transport across the cell membrane and subsequently escape from the secondary endosomes. We hypothesized that the biomechanical and thermodynamic interactions of NPs with plasma and endosomal membrane lipids are involved in these processes. Using model plasma and endosomal lipid membranes, we compared the interactions of cationic NPs composed of poly(d,l-lactide-co-glycolide) modified with the dichain surfactant didodecyldimethylammonium bromide (DMAB) or the single-chain surfactant cetyltrimethylammonium bromide (CTAB) vs anionic unmodified NPs of similar size. We validated our hypothesis in doxorubicin-sensitive (MCF-7, with relatively fluid membranes) and resistant breast cancer cells (MCF-7/ADR, with rigid membranes). Despite their cationic surface charges, DMAB- and CTAB-modified NPs showed different patterns of biophysical interaction: DMAB-modified NPs induced bending of the model plasma membrane, whereas CTAB-modified NPs condensed the membrane, thereby resisted bending. Unmodified NPs showed no effects on bending. DMAB-modified NPs also induced thermodynamic instability of the model endosomal membrane, whereas CTAB-modified and unmodified NPs had no effect. Since bending of the plasma membrane and destabilization of the endosomal membrane are critical biophysical processes in NP cellular uptake and endosomal escape, respectively, we tested these NPs for cellular uptake and drug efficacy. Confocal imaging showed that in both sensitive and resistant cells DMAB-modified NPs exhibited greater cellular uptake and escape from endosomes than CTAB-modified or unmodified NPs. Further, paclitaxel-loaded DMAB-modified NPs induced greater cytotoxicity even in resistant cells than CTAB-modified or unmodified NPs or drug in solution, demonstrating the potential of DMAB-modified NPs to overcome the transport barrier in resistant cells. In conclusion, biomechanical interactions with membrane lipids are involved in cellular uptake and endosomal escape of NPs. Biophysical interaction studies could help us better understand the role of membrane lipids in cellular uptake and intracellular trafficking of NPs.

Unprecedented reactivity of alkoxo/hydroxide-bridged dinuclear copper(II) complexes as artificial carboxylesterase: Effects of Gemini 16-6-16 micelles and bimetallic synergistic effect

One μ-alkoxo/hydroxide-bridged dinuclear copper(II) complex (Cu2L) and a mononuclear analogue (CuL) with symmetric Schiff base compound were employed as carboxylesterase models to promote the hydrolysis of a carboxylic acid ester, p-nitrophenyl picolinate (PNPP). Also the introducing of a Gemini surfactant, bis(hexadecyldimethylammonium)hexane bromide (16-6-16, 2Br−), gave interested observations relative to those controlled trials preformed in buffer and a micellar solution of traditional single-chain surfactant, CTAB (cetyltrimethylammonium bromide). The results indicated that the dinuclear Cu2L efficiently accelerated PNPP hydrolysis with 18,096- and 49,569.6-fold rate enhancement under moderate conditions (pH 7.00, 25°C) in buffer and 16-6-16 micellar solution, respectively. Much greater rate enhancement was observed in 16-6-16 micelles in contrast with CTAB micelles, launching 1.6–2.6 folds difference in hydrolysis rate of PNPP at pH 7.00. Additionally, the Cu2L-induced PNPP hydrolysis showed a bell-shaped rate-pH profile, which is an enzyme-like behaviour. Interestingly, rate–pH curves could provide the direct evidence for the interfacial effects of Gemini 16-6-16 micelles on the deprotonation of coordinated water, indicating about 0.2 unit pKa1 difference of the Cu2L-bound H2O between in micellar phase and bulk phase. Cu2L was found to be approximately 199.3- and 288.7-fold reactive than CuL in buffer and 16-6-16 micellar solution, respectively. Significant activity difference between both complexes probably results from the bimetallic coorperation of the two catalytic copper sites and more open binding site of Cu2L.

Phase-transfer catalysis of a new cationic gemini surfactant with ester groups for nucleophilic substitution reaction

Abstract A highly effective phase transfer of a quaternary ammonium gemini surfactant with ester groups ((diethylhexanedioate) diyl-α,ω-bis(dimethyl dodecyl ammonium bromide) referred to as 12-10-12) was synthesized with high yield and characterized by infrared spectroscopy, elemental analysis and 1H-NMR. Then, 12-10-12 was used as a phase transfer catalyst to study the catalytic effect on the reaction of anhydrous sodium acetate and 4-methylbenzyl chloride. The possible catalytic mechanism and the influence of surfactant concentration, temperature and type are also discussed. The experimental results showed that the catalysis efficiency was more active than the traditional, single-chained surfactant, tetrabutyl ammonium bromide. It also revealed that the reaction was first-order with respect to the concentration of 4-methylbenzyl chloride. The concentration of 4-methylbenzyl chloride grew linearly with the concentration of 12-10-12 and as the reaction temperature increased. The optimum reaction time was 7 h.

Efficient Preparation of Novel Phenolic Surfactants for Self-Assembled Monolayers

Novel molecules have been synthesized that combine the phenolic nature of tannins and self-assembling properties of surfactants. These single-chain (C12) surfactants with potential biocompatibility have been synthesized with an ω-thiol or disulfide functionality, both commonly used anchors in self-assembly onto gold surfaces, using a modular route. Protecting groups for the phenol and thiol moieties played a key role for overcoming the challenges often associated with the purification of surfactants. The tasks of unmasking the thiol moiety and simultaneously deprotecting the acetyl protecting groups of the phenols were accomplished using sodium thiomethoxide. This modular route can be extended to synthesize other surfactants with the potential ability to form robust layers with biocompatible properties. [Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]

Interaction between cationic gemini surfactant and related single-chain surfactant in aqueous solutions

In this paper, the gemini surfactants of type alkanediyl-α-ω-bis (alkyldimethylammonium) dibromide with different spacers containing s carbon atoms, referred to as “16-s-16” [C16H33(CH2)2N+(CH2)SN+(CH2)2C16H33·2Br−], (s=2, 6, 10 and Ar (8)) have been synthesized, purified and characterized in our laboratory. The interactions between geminis and their conventional monomeric surfactant hexadecyltrimethylammonium bromide (CTAB) have been studied using the conductivity and steady-state fluorescence quenching techniques at a certain micellar concentration range and certain temperature. Using the conductance data, the values of critical micelle concentrations (CMC) of the binary gemini–conventional mixtures having different compositions have been obtained. The micellar interaction parameters, (β), were determined from the critical micelle concentration values using the approach of Rubingh's regular solution theory. Mixed systems were exhibited negative synergism due to positive β values. The β values were found as close to zero. This indicates that the mixed micelle formation is ideal for all studied mixtures. The micelle aggregation numbers (Nagg), evaluated using steady-state fluorescence quenching at a total concentration of 2mM for CTAB/16-s-16 (s=2, 6, 10 and Ar (8)) systems. It was observed that contribution of conventional surfactants was always more than that of the geminis. Using the ratio of peak intensities, the micro-polarity, dielectric constant and binding constant (Ksv) of mixed systems were determined.

Interfacial Tensions for System of n-Heptane + Water with Quaternary Ammonium Surfactants and Additives of NaCl or C2–C4 Alcohols

Interfacial tensions of the oil–water interface versus surfactant concentration for n-heptane + water system with each of six single chain quaternary ammonium surfactants, and six Gemini quaternary ammonium surfactants around their critical micelle concentrations (CMC) have been measured by using the spinning drop method. The influences of additives (NaCl, ethanol, n-propanol, and n-butanol) on the interfacial tensions have also been investigated. It is observed that all of the surfactants can significantly lower the interfacial tensions of the n-heptane + water system. The required concentrations to reach the lowest interfacial tensions for Gemini surfactants with C12 and C14 alkyl chains are less than 10 % of those values for the corresponding single chain surfactants. For the n-heptane + water + Gemini surfactant systems, the addition of NaCl can lower the required surfactant concentrations to obtain the lowest interfacial tensions; however, the addition of C2–C4 alcohols has no evident effects but leads to a slight decrease of the values of these interfacial tensions.

Solubilization of polycyclic aromatic hydrocarbons in aqueous sodium dioctylsulfosuccinate solutions

Molar solubilization ratio (MSR) of sodium dioctylsulfosuccinate (AOT), a double-chained anionic surfactant, has been determined in aqueous medium for five polycyclic aromatic hydrocarbons (PAHs), viz., naphthalene, 2-methoxynaphthalene, 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane, 1,1-dichloro-2,2-bis(4-chlorophenyl)ethane and 1,1-dichloro-2,2-bis(4-chlorophenyl)ethylene by using spectrophotometric method. Partition coefficients of these PAHs in AOT solution have also been evaluated. Micellar shape and substituent group in the PAH are found to affect the value of MSR. AOT appears to have higher solubilization power compared to other single-chained ionic surfactants and could be a potential surfactant for soil remediation.

Effects of Cationic Ammonium Gemini Surfactant on Micellization of PEO–PPO–PEO Triblock Copolymers in Aqueous Solution

Effects of cationic ammonium gemini surfactant hexamethylene-1,6-bis(dodecyldimethylammonium bromide) (12-6-12) on the micellization of two triblock copolymers of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide), F127 (EO97PO69EO97) and P123 (EO20PO70EO20), have been studied in aqueous solution by differential scanning calorimetry (DSC), dynamic light scattering (DLS), isothermal titration calorimetry (ITC), and NMR techniques. Compared with traditional single-chain ionic surfactants, 12-6-12 has a stronger ability of lowering the CMT of the copolymers, which should be attributed to the stronger aggregation ability and lower critical micelle concentration of 12-6-12. The critical micelle temperature (CMT) of the two copolymers decreases as the 12-6-12 concentration increases and the ability of 12-6-12 in lowering the CMT of F127 is slightly stronger than that of P123. Moreover, a combination of ITC and DLS has shown that 12-6-12 binds to the copolymers at the temperatures from 16 to 40 °C. At the temperatures below the CMT of the copolymers, 12-6-12 micelles bind on single copolymer chains and induce the copolymers to initiate aggregation at very low 12-6-12 concentration. At the temperatures above the CMT of the copolymers, the interaction of 12-6-12 with both monomeric and micellar copolymers leads to the formation of the mixed copolymer/12-6-12 micelles, then the mixed micelles break into smaller mixed micelles, and finally free 12-6-12 micelles form with the increase of the 12-6-12 concentration.

Study of single and double chain surfactant–cobalt(iii) complexes and their hydrophobicity, micelle formation, interaction with serum albumins and antibacterial activities

Single and double chain surfactant–cobalt(iii) complexes show respectively, electrostatic and hydrophobic interactions with serum albumins.

Preparations of Ethosome-like Catanionic Vesicles from Ion-Pair Amphiphiles( IPAs ) for Dermal Drug Delivery

ABSTRACTEthosomes which are phospholipid vesicular systems embodying ethanol in relatively high concentrations have ever been discovered for enhanced skin delivery of drugs. The development of competent ethosome-like catanionic vesicles for dermal drug delivery is demonstrated in this work. Double-chained ion-pair-amphiphiles (IPAs or catanionic surfactants) were prepared from single-chained cationic and anionic surfactants by the precipitation method. These lipid-like surfactants were thereafter used as the material to prepare the catanionic vesicles with the aid of ethanol as the cosolvent in aqueous buffer solution by a simple semispontaneous process. Formability and physical stability of the as-prepared ethosome-like catanionic vesicles were discussed based on the viewpoint of mixed solvent dielectric constant. The potential application of the ethosome-like catanionic vesicles as nano-carriers in dermal drug delivery was illustrated by the encapsulation of hydrophobic and hydrophilic drugs. Furthermore, effects of ethanol and cholesterol addition on physical stability, bilayer membrane rigidity, encapsulation efficiency, and release rate of the ethosome-like catanionic vesicles were systematically studied. The performance of ethosome-like catanionic vesicles as drug delivery nano-carriers, eventually, can be tailored by the concentrations of ethanol and. cholesterol. The results of gelation of drugs loaded ethosome-like catanionic vesicles by water soluble polymers with and without hydrophobical modifications, as revealed by the phase maps and the rheological properties, then provide useful information for practical use of the ethosome-like catanionic vesicles in dermal delivery of drugs.

Colloidal and biological properties of cationic single-chain and dimeric surfactants

The colloidal and biological properties of the two single-chain surfactants N-benzyl-N,N-dimethyl-N-(1-dodecyl)ammonium bromide (PH12) and N-cyclohexylmethyl-N,N-dimethyl-N-(1-dodecyl)ammonium bromide (CH12) and their two dimeric counterparts N,N’-(1,3-phenylenebis(methylene))bis(N,N-dimethyl-N-(1-dodecyl)ammonium dibromide (12PH12) and N,N’-(cyclohexane-1,3-diylbis(methylene))bis(N,N-dimethyl-N-(1-dodecyl)ammonium dibromide (12CH12) were investigated. The thermodynamic functions of the self-aggregation process were estimated by using calorimetric measurements and the micellization enthalpy values, ΔHM, were examined considering the different enthalpic contributions to ΔHM. In the investigation of the structure-property relationship, it was found that the surfactant structure does not influence practically the foamability of the surfactants, but it plays a key role in their solubilization capacity, antimicrobial activity and biodegradability.

Complex Formation and Aggregate Transitions of Sodium Dodecyl Sulfate with an Oligomeric Connecting Molecule in Aqueous Solution

Anionic single-tail surfactant sodium dodecyl sulfate (SDS) and a molecule with multiple amido and amine groups (Lys-12-Lys) were used as building blocks to fabricate oligomeric surfactants through intermolecular interactions. Their interactions and the resultant complex and aggregate structures were investigated by turbidity titration, isothermal titration microcalorimetry, dynamic light scattering, cryogenic transmission electron microscopy, freeze-fracture transmission electron microscopy, (1)H NMR, and 1D NOE techniques. At pH 11.0, the interaction between SDS and Lys-12-Lys is exothermic and mainly resulted from hydrogen bonding among the amido and amine groups of Lys-12-Lys and the sulfate group of SDS and hydrophobic interaction between the hydrocarbon chains of SDS and Lys-12-Lys. At pH 3.0, each Lys-12-Lys carries four positive charges and two hydrogen bonding sites. Then SDS and Lys-12-Lys form complexes Lys-12-Lys(SDS)6 and Lys-12-Lys(SDS)4 through the head groups by electrostatic attraction and hydrogen bonds assisted by hydrophobic interaction. Moreover, the complexes pack more tightly in their aggregates with the increase of the molar ratio. Especially the Lys-12-Lys(SDS)4 and Lys-12-Lys(SDS)6 complexes behave like oligomeric surfactants taking Lys-12-Lys as a spacer group, exhibiting a series of aggregates transitions with the increase of concentration, i.e., larger vesicles, smaller spherical micelles, and long threadlike micelles. Therefore, oligomeric surfactants Lys-12-Lys(SDS)4 and Lys-12-Lys(SDS)6 have been successfully fabricated by using a single chain surfactant and an oligomeric connecting molecule through noncovalent association.

The ability of single-chain surfactants to emulsify an aqueous-based liquid crystal oscillates with odd–even parity of alkyl-chain length

The physical properties of many organic molecules often oscillate when the number of carbons in their aliphatic chains changes from odd to even. This odd–even effect for single-chain surfactants in solution is rarely observed. Here, we report the ability of single-chain surfactants to emulsify a class of non-amphiphilic organic salts, disodium cromoglycate (5′DSCG) oscillates as a function of the odd or even number of the aliphatic carbons. This system provides a water-in-oil-in-water emulsion, in which aqueous droplets of 5′DSCG in liquid crystal phases are coated with single-chain surfactants in a bulk carrying aqueous solution. For both surfactants of CH3(CH2)nOSO3-Na+ and CH3(CH2)nCOO−Na+, the ability to emulsify 5′DSCG molecules in water is stronger for surfactants with an odd number of sp3-hybridized carbon atoms in the aliphatic chains than those with an even number. This observed odd–even effect is consistent with the notion that conventional micelles possess a core of randomly arranged surfactant hydrocarbon tails. However, this water-in-oil-in-water resembles a vesicle system in which the surfactants assemble in a highly ordered structure that separates two aqueous systems. These new self-assembled phases have potential application in the formulation and design of new organic soft materials.