Alkyl Chain Length Of Surfactant Research Articles

A co-delivery platform based on plasmid DNA peptide-surfactant complexes: formation, characterization and release behavior.

The development of delivery systems based on cell penetrating peptides represents an incredible asset and may deeply contribute for the evolution of therapies efficacy. In this context, we explore the plasmid DNA (pDNA) condensation ability of TAT peptide to produce a suitable intracellular delivery platform. The nanoparticles were formed at various ratios of nitrogen to phosphate groups (N/P) and the variation of polyplexes properties with this parameter was studied. Beyond the large size exhibited by these carriers, their low pDNA immobilization profile instigates the need for an additional compacting agent. To maximize the performance of this peptide delivery system, a series of alkyl trimethyl ammonium bromide surfactants (CnTAB) were employed to further condense pDNA. In general, not only this strategy promotes the formation of lower sized vectors, but also greatly enhances particle characteristics such as surface charge and pDNA encapsulation. The magnitude of this effect is intimately dependent on surfactant chain length. Furthermore, the known cytotoxicity of cationic surfactants has been dramatically reduced by their incorporation into TAT/pDNA complexes. The release kinetics can be tailored and optimized to promote the controlled/sustained release of pDNA. Following this, the surfactant alkyl chain length and the N/P ratio are important controlling parameters. In addition, doxorubicin and paclitaxel can be efficiently loaded and encapsulated into peptide/pDNA/surfactant carriers. The presented platform reveals a great potential for therapeutic payloads loading and controlled release open advanced and new approaches in the design/formulation of innovative biomedical systems towards clinical translation.

Synthesis and characterization of silver nanoparticles in aqueous solutions of surface active imidazolium-based ionic liquids and traditional surfactants SDS and DTAB

This article reports synthesis and characterization of silver nanoparticles (AgNPs) in different concentrations of aqueous solutions of 1-octyl-3-methylimidazlium chloride ([C8mim]Cl), 1-octyl-3-methylimidazlium bromide ([C8mim]Br), 1-decyl-3-methylimidazlium bromide ([C10mim]Br), 1-dodecyl-3-methylimidazlium bromide ([C12mim]Br), sodium dodecyl sulfate (SDS) and dodecyltrimethyl ammonium bromide (DTAB) as stabilizer at 298.15 K. The effects of type, alkyl chain length and concentration of surfactants on the size, concentration and stability of AgNPs were investigated by Ultraviolet-Visible spectroscopy (UV–Vis), Transmission Electron Microscopy (TEM), Small Angle X-ray Scattering (SAXS) and Dynamic Light Scattering (DLS). The length of alkyl chain of surfactants is determining factor in stability of nanoparticles so that the surfactants with 8 or less carbon atoms have no enough protecting effects and the synthesized AgNPs tend to coalesce immediately. Increase in the alkyl chain length from C8 to C12 led to increase in stability and concentration of AgNPs. It seems that, the hydrophobic interactions between surfactants and surface of AgNPs have more important role in the stability of silver nanoparticles and the order of stabilizing effect of the investigated surfactants is as: SDS > DTAB > [C12mim]Br > [C10mim]Br.

Nano‐Vehicles for Drug Delivery Using Low‐Cost Cationic Surfactants: A Drug Induced Structural Transitions

AbstractTailor‐made application of catanionic aggregates as drug delivery vehicle and as templates for organized nano‐assemblies makes them the best alternatives to liposomes and niosomes. Catanionic aggregates formed by using hydrotropic drug as one of the components pave way for the increased bioavailability thorough sustained contact time and release of the charged drug. In the present investigation, the molecular interaction between the anti‐inflammatory hydrotropic drug, diclofenac sodium (DS) with traditional low cost cationic surfactants with varying chain length is studied. A strong structural transition was observed using turbidity, viscosity, dynamic light scattering, zeta potential, 1H‐NMR, AFM, TEM and SANS techniques. The results suggested that spherically/elliptical shaped micellar aggregates are converted into vesicles through intermediate cylindrical/wormlike aggregates. We have characterized (size and shape) the drug‐surfactant system based on the concentration of the drug, and alkyl chain length of cationic surfactants. The drug loaded vesicles were tested at physiological temperature and were found to stable even at high loading. Due to low cost and high stability, present system could be used as low cost drug delivery vehicle.

Effect of Alkyl Chain Length of Ionic Surfactants on Selective Removal of Asphaltene from Oil Sand Bitumen

In an attempt to find a more effective way to separate asphaltene from bitumen froth or bitumen emulsion by utilizing solvents, we added four different types of cationic (pyridinium series) and anionic (sulfate series) surfactants having different alkyl chain lengths and then compared the results. The data of the experiments showed that at given conditions (n-heptane at 50 °C, solvent-to-bitumen ratio of 3, and 20% water) and based on feedstock treated with 0.4 mmol of surfactant, asphaltene–resin particles (colloid) with an initial negative charge showed different characteristics of adsorption of surfactants and aggregation of asphaltenes depending on the charge of the surfactants (cationic or anionic) and the alkyl chain length. Ultimately, the results showed that when methyl-pyridinium chloride (which is cationic and has the shortest alkyl chain) is added that the colloidal instability of asphaltene became the highest so that asphaltene removal increased by up to about 10% compared to treatments withou...

Synthesis of porous silica materials with tunable morphologies and nanopore sizes using heterogemini surfactants

A series of heterogemini surfactants C16H33OCH2CH(OH)CH2N+(CH3)2C n H2n+1·Br– were used as the template to synthesise porous silica materials via a Stober method. The influence of the alkyl chain length of heterogemini surfactants on the morphology of porous silica materials was studied. Porous silica materials were characterised by scanning electron microscopy, transmission electron microscopy and nitrogen adsorption–desorption analysis. Results showed that with the increase of alkyl chain length, the morphologies of porous silica materials gradually transform from sphere to sphere with cavity, sphere composed of vesicles, coral like and finally to lamella. Pore size of materials ranges from 1.17 to 3.93 nm. When the alkyl chain is short enough (n = 8 and 10), a hierarchical pore size distribution can be obtained. The possible formation mechanism of the porous silica materials has been discussed.

Effective removal of emulsified oil from oily wastewater using surfactant-modified sepiolite

Abstract In this study, tetradecyl trimethylammonium bromide (TTAB), cetyl trimethylammonium bromide (CTAB), and octadecyl trimethylammonium bromide (OTAB) were used to modify natural sepiolite via an ion exchange reaction to form organic sepiolite (organo-Sep) hybrids. This modification is particularly critical in order to obtain good affinity between organo-Sep hybrids and emulsified oil droplets (EOs). The loading surfactants changed the surface wettability from highly hydrophilic to increasingly hydrophobic, and a charge inversion from negative to positive occurred. Organo-Sep hybrids were investigated as adsorbents for removing emulsified oil from simulated oily wastewater. The morphology, texture, and surface properties of Sep and organo-Sep hybrids were characterized by various characteristic techniques, including SEM, XRD, FT-IR, contact angle analyzer, surface area analyzer, and ζ-potential analyzer. After modification, the BET surface area of Sep significantly increased from 297.8 to 698.6 m2/g, while the total pore volume of Sep raised from 0.840 to 3.080 cm3/g with an increase in alkyl chain length of surfactants. Experimental data showed that initial pH and temperature were two key factors affecting adsorption efficiency. It was observed that 98–99% of EOs was successfully removed by organo-Sep hybrids at 60 °C. The maximum adsorption capacities of TTAB-Sep, CTAB-Sep, and OTAB-Sep for EOs were determined from Langmuir isotherm at pH 6 and 60 °C as 434.7, 448.3 and 454.9 mg/g, respectively, along with good recyclability of more than 5 cycles. Thermodynamic data suggested that the adsorption process was physical, spontaneous, and endothermic in nature. Results showed that the organo-Sep hybrids were promising adsorbent materials for the preconcentration and separation of EOs from oily wastewater.

The self-assembly of ionic liquids surfactants in ethanolammonium nitrate ionic liquid

Self-assembly of ionic liquids (ILs) surfactants in ILs solvents is important from the viewpoint of both scientific research and practical application because of the advantages of high ionic nature and possible application at high temperature. In this work, the aggregation behavior of long-chain ionic liquids 1-alkyl-3-methylimidazolium chloride [Cnmim]Cl (n = 12, 14, 16) and N-alkyl-N,N-dimethylethanolammonium [CnDMEA]Cl (n = 12, 14, 16) in a protic ionic liquid, ethanolammonium nitrate (EOAN), is investigated by surface tension measurements. The variation of micellization parameters with alkyl chain length and head group type of the ILs surfactants is analyzed and compared with that in water and in ethylammonium nitrate (EAN). It is found that the critical micelle concentration (cmc) values of the IL surfactants, such as [C12mim]Cl, in EOAN are 27 times smaller than those in EAN, and 4 times smaller than those in water. This suggests that EOAN is a better self-assembly medium for the ILs surfactants. It is also found that the contribution of head groups of the ILs surfactants to the cmc values is different in EOAN, water and EAN, while the contribution of CH2 group in the alkyl chain of the ILs surfactants is generally independent of the solvents nature.

Ionic Liquids as Micellar Agents in Perrhenate‐catalysed Olefin Epoxidation

AbstractThe perrhenate‐catalysed epoxidation of cyclooctene with aqueous H2O2was performed in micellar media using imidazolium‐based ionic liquids (ILs) as surfactants. The catalytic performance of perrhenate was greatly increased in micellar media compared to IL used as neat solvent which allows for efficient use both of catalyst and IL. The choice of the surfactant alkyl chain length (C6to C12) as well as the counterion (BF4−, TfO−, Cl−) is crucial for achieving high reaction rates. The positive effect of the addition of surfactants relies on formation of micelles. Best results are obtained for BF4−anion with long alkyl chain imidazolium cations, outperforming results for previously reported perrhenate ILs, while the use of Cl−anion leads only to similar reactivity. Cross‐over experiments revealed that the catalytically active micellar species forms in situ and that the BF4−anion promotes the reaction beyond a mere change in ionic strength. The use of Cl−anion as surfactant counterion bears potential as a novel approach for rapid screening of potentially catalytically active anions, which is exemplarily shown for tungstate anion.

Fluorescence Enhancement of a Cationic Fluorene-Phenylene Conjugated Polyelectrolyte Induced by Nonionic n-Alkyl Polyoxyethylene Surfactants.

The modulation of conjugated polyelectrolyte fluorescence response by nonionic surfactants is dependent on the structures of the surfactant and polymer, polymer average molecular weight, and polyelectrolyte-surfactant interactions. In this paper, we study the effect of nonionic n-alkyl polyoxyethylene surfactants (CiEj) with different alkyl chain lengths (CiE5 with i = 6, 8, 10, and 12) and number of oxyethylene groups (C12Ej with j = 5, 7, and 9) on the photophysics and ionic conductivity of poly{[9,9-bis(6'-N,N,N-trimethylammonium)-hexyl]-2,7-fluorene-alt-1,4-phenylene}bromide (HTMA-PFP) in dimethyl sulfoxide-water 4% (v/v). Molecular dynamics simulations show that HTMA-PFP chains tend to approach as the simulation evolves. However, the minimum distance between the polymer centers of mass increases upon addition of the surfactant and grows with both the surfactant alkyl chain length and the number of oxyethylene groups, although there are no specific polymer-surfactant interactions. A significant increase in the polymer emission intensity has been observed at surfactant concentrations around their critical micelle concentrations (cmcs), which is attributed to polymer aggregate disruption. However, an increase in the solution conductivity for concentrations above the C12E5 cmc has only been observed for the HTMA-PFP/C12E5 system. The enhancement of fluorescence emission intensity and conductivity upon surfactant addition increases with polymer average molecular weights and seems to be controlled by the polymer-surfactant proximity, which is maximum for C10E5 and C12E5.

Effect of the surfactant alkyl chain length on the stabilisation of lyotropic nematic phases

ABSTRACTLyotropic quaternary mixtures of potassium alkanoates (KCx) and sodium alkyl sulphates (NaCxS), where x is the number of carbon atoms in their alkyl chains, were prepared to investigate the effect of the surfactant alkyl chain length on the stabilisation of lyotropic nematic phases. The lyotropic mixtures investigated were formed by the dissolution of KCx (NaCxS) surfactants in the mixture of Rb2SO4/1-decanol/water (Na2SO4/1-decanol/water), separately. The uniaxial-to-biaxial nematic phase transitions were identified from the temperature dependence of the birefringences of the nematic phases by means of laser conoscopy. The micelle dimensions were obtained from small-angle X-ray scattering measurements. It was observed that the increase in the surfactant alkyl chain length causes the micellar growth in the plane perpendicular to the main amphiphile bilayer. The surfactant alkyl chain length plays a key role on the shape anisotropy of micelles, which triggers the orientational fluctuations that are responsible for the stabilisation of the different lyotropic nematic phases.

Influence of alkyl chain length of alpha olefin sulfonates on surface and interfacial properties

ABSTRACTAlpha olefin sulfonates (AOS) with various alkyl chain lengths have been used to investigate the influence of alkyl chain length on the interfacial properties at air–water, liquid paraffin–water, and parafilm–water interfaces. It was found that the critical micelle concentration decreased with increasing alkyl chain length, while the efficiency of reducing surface tension was inverse relationship with alkyl chain length. The diffusion coefficient obviously reduced with an increase of surfactant concentration and alkyl chain length. The C14-16AOS shows better wettability and emulsification than C16-18AOS and C20-24AOS. For foaming properties, the foamability and foam stability dramatically decreased with increasing alkyl chain length.

Phenol and/or Zn2 + adsorption by single- or dual-cation organomontmorillonites

Single- or dual-cation organomontmorillonites (OMt) modified by one or two cationic surfactants, respectively and/or cysteamine hydrochloride (CSH) were used to remove Zn2+ and/or phenol from aqueous solutions. The OMt were characterized by XRD, FTIR spectroscopy and N2 adsorption-desorption isotherm analyses. The adsorption results of Zn2+ and phenol showed that OMt had much larger adsorption capacities of phenol than that of Na+-Mt or CSH-Mt in the presence of Zn2+. Experiments with the simultaneous presence of both the contaminants showed that one did not affect the adsorption of the other with all the adsorbents. The uptakes of Zn2+ and phenol onto dual-cation OMt increased with increasing solution pH, contact time, temperature and initial concentration of Zn2+ and phenol. The adsorption equilibrium time was 10min for both contaminants and the maximum adsorption capacities of Zn2+ and phenol were found under alkaline environment. The adsorption of both Zn2+ and phenol can be better described by Freundlich model than Langmuir isotherm. Phenol adsorption onto OMt was caused primarily by partitioning into an organic phase in the interlayers, and the uptakes of phenol increased with increasing alkyl chain length and loading amount of surfactant in single-cation OMt. Zn2+ adsorption onto dual-cation OMt was due to ion exchange, formation of complexes and/or precipitation mechanism depending on the solution pH.

Switching chirality in the assemblies of bio-based amphiphiles solely by varying their alkyl chain length.

Here we show that chirality inversion can be realized solely by changing the alkyl chain length of sorbitol-alkylamine surfactants. The chirality switch phenomenon is attributed to twisting of a headgroup, which depends on the balance between hydrophobic interaction and torsional stress, resulting in various orientational orders in assemblies and chirality inversion.

Properties of Polystyrene Clay Nanocomposites Prepared Using Two New Imidazolium Surfactants

Montmorillonite/polystyrene nanocomposites were prepared by in situ photopolymerization of styrene in the presence of 2% by weight of clay organomodified by two new imidazolium surfactants having in their structure an alkyl chain with 20 or 22 carbon atoms, respectively. Thermogravimetry showed that the new surfactants are more thermally stable than conventional alkylammonium surfactants. The properties of the obtained nanocomposites were compared with those of pristine polystyrene, with those of a microcomposite obtained by in situ polymerization of styrene in the presence of unmodified clay, and with those of a nanocomposite obtained starting from an organomodified clay with a short alkyl chain (12 carbon atoms) imidazolium surfactant. XRD, TEM, and rheological analysis showed that the clay/PS nanocomposites have a mixture of intercalated and partially exfoliated structure layers, where the higher the surfactant alkyl chain length, the higher the exfoliation degree. Kinetics curve of accelerated UV aging, obtained by following through infrared spectroscopy the increase of carbonyl functions during aging, showed that the rate of photooxidation of clay containing samples is higher than neat polystyrene. The rate is higher as a function of the degree of dispersion of the filler in the polymer matrix.

Investigation of the alkyl chain lengths of surfactants on their adsorption by montmorillonite (Mt) from aqueous solutions

In this study, the behaviors of adsorption of six different quaternary ammonium salts onto montmorillonite (Mt) have been investigated. One of six cationic surfactants is branched (tetrabutylammonium bromide (C4)4ABr) and the others are linear (with five different hydrocarbon chain lengths, i.e. C16TABr, C14TABr, C12TABr, C10TABr, and C8TABr).The organoclays were characterized by spectroscopic techniques such as XRD and FT-IR. Their surface morphologies were also determined by using the SEM images. To reveal the adsorption mechanism, the measurements of contact angle and zeta potential of the samples were carried out. When the alkyl chain length increased, the adsorption ability of the surfactant adsorbed onto Mt surface increased. The effects of temperature, surfactant initial concentration and contact time onto the adsorption were investigated. The adsorption isotherms obtained show that the experimental isotherms exhibit a good fit with the Langmuir, Freundlich and Temkin adsorption models at all the temperatures, but the fit with models decreases with the decrease of chain length. The isosteric enthalpy and entropy changes were evaluated. The adsorption of surfactants onto Mt was found to be exothermic and spontaneous at all temperatures except for C10TABr adsorption. The interlayer distance and the packing density of surfactant ions in the interlayer region increased with increased chain length, as confirmed by the XRD patterns. FTIR spectrum and contact angle measurements of raw montmorillonite and organoclays indicate the incorporation of surfactants and the change in hydrophilicity of the organoclays. The values of zeta potential imply the presence of hydrophobic interactions between their hydrocarbon tails for C16TABr and partly for C14TABr adsorption. The negative values of zeta potential of other surfactants (C14TABr, C12TABr, C10TABr, C8TABr and (C4)4TABr) except for C16TABr compared to the raw clay indicate that the ion exchange is more effective according to electrostatic interactions in terms of the adsorption process.

Structural features and surfactant properties of core–shell type micellar aggregates formed by gemini piperidinium surfactants

Abstract Aqueous micellar solution of piperidinium gemini surfactants was investigated by small angle X-ray scattering (SAXS) and the real space structural information of the micelles was deduced by indirect Fourier transformation (IFT) method. The maximum dimension of the micelles and their shape were determined by evaluating the pair distance distribution function (PDDF) and the electron density profile of the aqueous surfactant solution. These gemini surfactants formed core–shell type micelles in the aqueous solution above their cmc values having ellipsoidal structure. The dilute aqueous solutions of these surfactants were further investigated to determine their surfactant properties by surface tension and conductivity method. The self-aggregation and thermodynamic properties as well as the shape, size and internal structure of the micelles formed by these surfactants were found to be dependent on the methylene spacer units and hydrophobic alkyl chain length of the gemini surfactants.

Impact of Alkyl Chain Length on the Transition of Hexagonal Liquid Crystal-Wormlike Micelle-Gel in Ionic Liquid-Type Surfactant Aqueous Solutions without Any Additive.

The search for functional supramolecular aggregations with different structure has attracted interest of chemists because they have the potential in industrial and technological application. Hydrophobic interaction has great influence on the formation of these aggregations, such as hexagonal liquid crystals, wormlike micelles, hydrogels, etc. So a systematical investigation was done to investigate the influence of alkyl chain length of surfactants on the aggregation behavior in water. The aggregation behavior of 1-hexadecyl-3-alkyl imidazolium bromide and water has been systematically investigated. These ionic liquid surfactants are denoted as C16-Cn (n = 2, 3, 4, 6, 8, 9, 10, 12, 14, 16). The rheological behavior and microstructure were characterized via a combination of rheology, cryo-etch scanning electron microscopy, polarization optical microscopy, and X-ray crystallography. The alkyl chain has great influence on the formation of surfactant aggregates in water at the molecular level. With increasing alkyl chain length, different aggregates, such as hexagonal liquid crystals, wormlike micelles, and hydrogels can be fabricated: C16-C2 aqueous solution only forms hexagonal liquid crystal; C16-C3 aqueous solution forms wormlike micelle and hexagonal liquid crystal; C16-C4, C16-C6 and C16-C8 aqueous solutions only form wormlike micelle; C16-C9 aqueous solution experiences a transition between wormlike micelle and hydrogel; C16-C10, C16-C12, C16-C14 and C16-C16 only form hydrogel. The mechanism of the transition of different aggregation with increasing alkyl chain length was also proposed.

Antibacterial Activity, in Vitro Cytotoxicity, and Cell Cycle Arrest of Gemini Quaternary Ammonium Surfactants.

Twelve gemini quaternary ammonium surfactants have been employed to evaluate the antibacterial activity and in vitro cytotoxicity. The antibacterial effects of the gemini surfactants are performed on Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) with minimum inhibitory concentrations (MIC) ranging from 2.8 to 167.7 μM. Scanning electron microscopy (SEM) analysis results show that these surfactants interact with the bacterial cell membrane, disrupt the integrity of the membrane, and consequently kill the bacteria. The data recorded on C6 glioma and HEK293 human kidney cell lines using an MTT assay exhibit low half inhibitory concentrations (IC50). The influences of the gemini surfactants on the cell morphology, the cell migration ability, and the cell cycle are observed through hematoxylin-eosin (HE) staining, cell wound healing assay, and flow cytometric analyses, respectively. Both the values of MIC and IC50 decrease against the growth of the alkyl chain length of the gemini surfactants with the same spacer group. In the case of surfactants 12-s-12, the MICs and IC50s are found to decrease slightly with the spacer chain length changing from 2 to 8 and again to increase at higher spacer length (s = 10-12). All of the gemini surfactants show great antibacterial activity and cytotoxicity, and they might exhibit potential applications in medical fields.

Polyethylenimine coated plasmid DNA–surfactant complexes as potential gene delivery systems

Nanometer scaled particles have been prepared from strong association between plasmid DNA (pcDNA3-FLAG-p53) and oppositely charged surfactants. Although these particles present suitable properties for gene delivery purposes, their cytotoxicity could compromise their use in gene therapy applications. To ensure biocompatibility of this potential gene delivery system, the nanoparticles were coated with polyethylenimine (PEI) with various molar ratios of PEI nitrogen to plasmid DNA phosphate groups. This led to a drastic increase in the cell viability of the particles, and in addition particle characteristics such as size, surface charge and loading efficiency, have also been enhanced as a result of the PEI coating process. The dissolution or swelling/deswelling behaviour displayed by these particulate vehicles could be tailored and monitored in time, to promote the controlled and sustained release of plasmid DNA. Moreover, we show that both the surfactant alkyl chain length and the ratio of nitrogen to phosphate groups are important parameters for controlling the plasmid DNA release. Overall, the developed plasmid DNA carriers have the potential as a new nanoplatform to be further explored for advances in the gene therapy field.

Influence of sugar surfactant structure on the encapsulation of oil droplets in an amorphous sugar matrix during freeze-drying

The encapsulation of O/W emulsion droplets in a freeze-dried amorphous sugar matrix was investigated, focusing on the impact of the molecular structure of the emulsifying surfactant. O/W emulsions, containing various surfactants, were freeze-dried in the presence of a sugar. Thirty types of surfactants, including eighteen different sugar surfactants and ten types of commercially available sugar ester mixtures, were used. Linoleic acid methyl ester and trehalose were used as the oil phase and sugar. The amounts of oil droplets encapsulated in freeze-dried amorphous sugar matrix were analyzed by Fourier transform Infrared spectroscopy. Sugar surfactants were generally superior to the other classes of surfactants for oil droplet encapsulation during freeze-drying, and there was the optimum alkyl chain length of the sugar surfactant. Sugar esters generally exhibited greater oil encapsulation than sugar ethers. Larger sugar head group appeared to result in better encapsulation in the case of sugar esters, but the opposite tendency was found for sugar ethers. A limited combination of sugar surfactants (15% sucrose mono- and 85% di-stearate) resulted in the maximum oil droplet encapsulation efficiency although these surfactants are individually quite poor in the encapsulation and other tested combinations did not improve the encapsulation efficiency relative to their individual effectiveness.