Structure Of Nonionic Surfactants Research Articles

Niosomes: A targeted drug delivery system

Niosomes are the multilamellar vesicles structure of non-ionic surfactant. Niosomes act as a drug carrier in drug delivery system. Niosomes improved the therapeutic performance of encapsulated drug molecules by protecting the drug from host biological environments resulting in their delayed clearance. In this present review article, we concentrate on the drug Niosomes which is a normal approach for drug delivery system. The niosomes have become the area of interest in the drug delivery system their advantage one liposomes in the field of drug delivery system for being non-toxic makes them more suitable for drug delivery system. Their ability to encapsulate both hydrophilic, lipophilic drugs simultaneously has increased its demand in the present scenario. Niosomes are vesicles made up of non-ionic surfactant, which are biodegradable, nontoxic, more stable and inexpensive and have ability to substitute liposomes but they also flexibility in the route of administration Thus, in the present articles more focus is made on the development method of niosomes which is used as a novel approach in present scenario So, Niosomes as a drug carrier is of greater Importance in the pharmaceutical field

Micelle structure of nonionic surfactants containing carbon dioxide moieties in protic ionic liquids

Partial substitution of ethylene oxide with carbon dioxide moieties can yield greener nonionic surfactants with comparable functionalities. In water, studies showed that the incorporation of CO2 moieties suppresses the formation of liquid crystalline phases at high concentrations. A similar reduction in solvation and suppression of liquid crystal formation is observed here in the ionic liquids ethylammonium nitrate and propylammonium nitrate. Small-angle neutron scattering is used to study the solvation and packing of micelles in ionic liquids as functions of temperature, concentration, and content of CO2 moieties. By comparing with aqueous solutions, this work shows that while the nature of surfactant-solvent interaction is comparable among water and alkylammonium nitrate ILs, their behaviours in the solvated micelle shell are different. The lack of liquid crystalline phases should be attributed to the small excluded volume of micelles, which can be fine-tuned via ion design and choice of solvent.Graphical

On the relationship between the properties of planar structures of non-ionic surfactants and their vesicular analogues – Niosomes

In recent years, the study of niosomes as nanocarriers alternative to liposomes has received increasing attention. In contrast to well-studied liposome membranes, many aspects of the behavior of analogous niosome bilayers have not been studied. This paper considers one of these aspects related to the communication between the physicochemical properties of planar and vesicular objects. We present the first results of comparative studies of Langmuir monolayers of binary and ternary (with cholesterol) mixtures of non-ionic surfactants based on sorbitan esters and niosomal structures assembled from the same materials. The Thin-Film Hydration (TFH) method in the gentle shaking version was used to produce the particles of large sizes, while small unilamellar high quality vesicles with a unimodal distribution of particles were prepared by TFH using ultrasonic treatment and extrusion. An analysis of the structural organization and phase state of monolayers based on compression isotherms and supplemented by thermodynamic calculations, as well as the results of determining the particle morphology, polarity and microviscosity of niosome shells, made it possible to obtain fundamental data on the intermolecular interactions of the components and their packing in shells and to relate these data to the properties of niosomes. This relationship can be used to optimize the composition of niosome membranes and predict the behavior of these vesicular systems. It was shown that cholesterol excess creates regions of bilayers with increased rigidity (like “lipid rafts”), which hinders the process of folding film fragments into small niosomes.

Forecasting the cloud point of alkoxylated nonionic surfactants

AbstractThe highest effectiveness of detergency for nonionic surfactants is observed in the proximity of the cloud point. This phenomenon is primarily influenced by surfactant molecular structure, such as carbon chain length and type of the hydrophilic components. Target of this investigation is to identify a relationship between the cloud point and the structure of nonionic surfactants based on ethoxylated (CnEm), ethoxylated‐propoxylated (CnEmPp) and propoxylated‐ethoxylated (CnPpEm) fatty alcohols. Three hundred and fifty nonionic surfactants have been prepared for this purpose. These surfactants differ in the C‐chain lengths, C4/C6 to C20/C22, and the amount of ethylene oxide (EO range [n] 2–22 ethoxylation) and propylene oxide (PO range [p] 0–12 propoxylation) moieties. Mapping the differences in the performance allows us to propose a high‐accuracy topological model describing the structure influence on the cloud point.

Chemically Tuning Attractive and Repulsive Interactions between Solubilizing Oil Droplets

AbstractMicellar solubilization is a transport process occurring in surfactant‐stabilized emulsions that can lead to Marangoni flow and droplet motility. Active droplets exhibit self‐propulsion and pairwise repulsion due to solubilization processes and/or solubilization products raising the droplet's interfacial tension. Here, we report emulsions with the opposite behavior, wherein solubilization decreases the interfacial tension and causes droplets to attract. We characterize the influence of oil chemical structure, nonionic surfactant structure, and surfactant concentration on the interfacial tensions and Marangoni flows of solubilizing oil‐in‐water drops. Three regimes corresponding to droplet “attraction”, “repulsion” or “inactivity” are identified. We believe these studies contribute to a fundamental understanding of solubilization processes in emulsions and provide guidance as to how chemical parameters can influence the dynamics and chemotactic interactions between active droplets.

Chemically Tuning Attractive and Repulsive Interactions between Solubilizing Oil Droplets.

Micellar solubilization is a transport process occurring in surfactant-stabilized emulsions that can lead to Marangoni flow and droplet motility. Active droplets exhibit self-propulsion and pairwise repulsion due to solubilization processes and/or solubilization products raising the droplet's interfacial tension. Here, we report emulsions with the opposite behavior, wherein solubilization decreases the interfacial tension and causes droplets to attract. We characterize the influence of oil chemical structure, nonionic surfactant structure, and surfactant concentration on the interfacial tensions and Marangoni flows of solubilizing oil-in-water drops. Three regimes corresponding to droplet "attraction", "repulsion" or "inactivity" are identified. We believe these studies contribute to a fundamental understanding of solubilization processes in emulsions and provide guidance as to how chemical parameters can influence the dynamics and chemotactic interactions between active droplets.

Study of the spontaneous nano-emulsification process with different octadecyl succinic anhydride derivatives

Three new amphiphilic molecules were synthetized on a basis of a common monomer, octadecyl succinic anhydride (OSA), on which were grafted different PEGylated hydrophilic polar head. The objective of this study is to investigate a potential relationship between the chemical structure of the surfactant, and the efficiency to generate nano-emulsions through the spontaneous nano-emulsification method. Beyond the innovative synthesis and comparison of these amphiphiles, a comprehensive comparison is suggested, comparing size distribution and polydispersity for the different composition parameters, as well making a bridge with critical micelle concentration and hydrophile lipophile balance (HLB). Using OSA monomeric entity as common hydrophobic moiety, the variations in the surfactant molecules were done on the hydrophilic moiety, through the addition of one or two Jeffamine chains in different configurations, so-called C18⊖-PEG, C18-PEG and C18-PEG2. The results disclosed that C18⊖-PEG allows producing smallest size distribution and lowest PDI values. Moreover, C18⊖-PEG presents the highest critical micellar concentration, linked to a higher hydrophilicity of the molecule. This impacts the balance between surfactant affinity for oil and aqueous phases, a point probably related to the spontaneous emulsification efficiency. A last part of the study regarded the optimization of the emulsification efficiency, through a systematic study in ternary composition map, to disclosed that the best conditions are included in the lower surfactant concentrations, for water and oil contents higher and lower than 50%, respectively. The main idea behind this study was to bring further insights into the unclear relationship between the chemical structure of nonionic surfactants, and the efficiency of the emulsification by spontaneous low-energy method.

The Accumulated Effect of the Number of Ethylene Oxide Units and/or Carbon Chain Length in Surfactants Structure on the Nano-Micellar Extraction of Flavonoids.

Classical extraction methods used for isolation of active substances from plant material are expensive, complicated and often environmentally unfriendly. The ultrasonic assistance micelle-mediated extraction method (UAMME), based on green chemistry principles, seems to be an interesting alternative. This work aimed to find a connection between the chemical structure of non-ionic surfactants and the efficiency of the extraction process. The effect of hydrophobic chain length and number of ethoxy groups on the quality of Bidens tripartite extracts was investigated. Several ethoxylated fatty alcohols were used: Ceteareth-20, Steareth-20, Oleth-20, Oleth-10, Oleth-5, C12-C13 Pareth-12, C12-C15 Pareth-12 and Ceteareth-12. The bioflavonoid compositions with the HPLC method was determined. The hydrophilic lipophilic balance (HLB) of studied surfactants, as well as the surface tension of surfactant solutions, were compared, to determine the explanation for the obtained differences in bioflavonoids concentration. The structural changes influenced by polyphenol extraction were monitored using Dynamic Light Scattering (DLS) measurements. In this work, probably for the first time, the connection between the chemical structure of non-ionic surfactants and the efficiency of the extraction process was found. The experimental and theoretical approach rationalized the choice of an appropriate eluent. We propose some structurally dependent factors, whose optimal value gave a high efficiency to the UAMME.

Structural Characterization of Biocompatible Reverse Micelles Using Small-Angle X-ray Scattering, 31P Nuclear Magnetic Resonance, and Fluorescence Spectroscopy

The most critical problem regarding the use of reverse micelles (RMs) in several fields is the toxicity of their partial components. In this sense, many efforts have been made to characterize nontoxic RM formulations on the basis of biological amphiphiles and/or different oils. In this contribution, the microstructure of biocompatible mixed RMs formulated by sodium 1,4-bis-2-ethylhexylsulfosuccinate (AOT) and tri- n-octylphosphine oxide (TOPO) surfactants dispersed in the friendly solvent methyl laurate was studied by using SAXS and 31P NMR and by following the solvatochromic behavior of the molecular probe 4-aminophthalimide (4-AP). The results indicated the presence of RM aggregates upon TOPO incorporation with a droplet size reduction and an increase in the interfacial fluidity in comparison with pure AOT RMs. When confined inside the mixed systems, 4-AP showed a red-edge excitation shift and confirmed the increment of interfacial fluidity upon TOPO addition. Also, the partition between the external nonpolar solvent and the RM interface and an increase in both the local micropolarity and the capability to form a hydrogen bond interaction between 4-AP and a mixed interface were observed. The findings have been explained in terms of the nonionic surfactant structure and its complexing nature expressed at the interfacial level. Notably, we show how two different approaches, i.e., SAXS and the solvatochromism of the probe 4-AP, can be used in a complementary way to enhance our understanding of the interfacial fluidity of RMs, a parameter that is difficult to measure directly.

A Systematic Study on the Impact of Surfactant Chain Length on Dynamic Interfacial Properties in Porous Media: Implications for Enhanced Oil Recovery

We propose a new systematic procedure to investigate the effect of hydrophobic and hydrophilic chain lengths of polyoxyethylenated (POE) nonionic surfactants on dynamic interfacial properties in porous media. We study the impact of nonionic surfactant structure on oil recovery through comprehensive experimental measurements of phase behavior, cloud point, dynamic interfacial tension, dynamic contact angle, and spontaneous and forced imbibitions at ambient and reservoir conditions. We identify a surfactant structure that increased the oil production by 22% and 6% compared to tap water and a nonionic surfactant commercially deployed in a major unconventional oil reservoir, respectively. In this work, we observe that factors such as minimum interfacial tension used for surfactant selection are not the only parameters influencing displacements at the pore scale. The results of this study reveal that when a surfactant solution imbibes into the pore space as an invading phase, the surfactant ability to lower th...

Nonionic surfactant structure on the drug release, formulation and physical properties of ethylcellulose microspheres

Evaluate the effects of nonionic surfactants Brij 58 and Tween 40 with different structures but similar hydrophilic lipophilic balances (HLBs) on theophylline (TH)-loaded ethylcellulose (EC) microspheres. Microspheres were formulated using ratios of the surfactants with matching HLB values but different chemical-structures at temperatures (22/35 °C) by hydrophobic solvent-emulsion evaporation. Particle size, GMD, drug loading, encapsulation efficiency and dissolution were evaluated. Drug release was determined using the zero- and first-order, Higuchi and Hixson–Crowell models. EC microspheres prepared with surfactant Brij 58 showed discrete, free-flowing spherical particles, solid interiors and increased particle smoothness as temperature increased; those prepared with Tween 40 appeared porous with coarser surface morphology as temperature increased; both were CHLB (Combined HLB) dependent. Dissolution obeyed the Higuchi model drug release for both microspheres prepared with Tween 40 and Brij 58 except for those prepared with Brij 58 at 35 °C, which presented as zero order. The results were ascribed to the different chemical structure of Brij 58 versus Tween 40 and preparation temperature. Surfactant chemical structure is an unreported processing parameter shown here to be important in microsphere formulation. Brij 58 possesses properties unique to its chemical structure that influence pharmaceutical and molecular biopharmaceutical research.

Tetraazachlorins self-organization in micellar systems

The effect of the structure of nonionic surfactants on the self-organization (aggregation) of the hydrophobic compound β,β,β′,β′-tetramethyltribenzotetraazachlorin solubilized in solutions of these surfactants has been investigated in the present work. Changes in the spectral properties of the solute resulting from its aggregation were assessed. The degree of β,β,β′,β′-tetramethyltribenzotetraazachlorin aggregation has been shown to depend on the length of the hydrophobic moiety of the surfactant molecule. Evidence on the absence of correlation between the degree of aggregation of the solubilized photosensitizer and the numeric value of the hydrophilic-lipophilic balance of the surfactant has been obtained. The method of dynamic light scattering has been used to show that the dynamic rearrangement of micelles is one of the reasons for the aggregation of substituted tetraazachlorins in colloidal solutions of nonionic surfactants. The study of changes in the aggregation degree of tetraazachlorins in solutions of nonionic surfactants at dilution proved the possibility of redistribution of solubilized photosensitizer in investigated micellar systems.

Modeling of the Critical Micelle Concentration (CMC) of Nonionic Surfactants with an Extended Group-Contribution Method

A group-contribution (GC) property prediction model for estimating the critical micelle concentration (CMC) of nonionic surfactants in water at 25 °C is presented. The model is based on the Marrero and Gani GC method. A systematic analysis of the model performance against experimental data is carried out using data for a wide range of nonionic surfactants covering a wide range of molecular structures. As a result of this procedure, new third order groups based on the characteristic structures of nonionic surfactants are defined and are included in the Marrero and Gani GC model. In this way, those compounds that exhibit larger correlation errors (based only on first- and second-order groups) are assigned to more detailed molecular descriptions, so that better correlations of critical micelle concentrations are obtained. The group parameter estimation has been performed using a data set of 150 experimental measurements covering a large variety of nonionic surfactants including linear, branched, and phenyl a...

Solubilization capacity of nonionic surfactant micelles exhibiting strong influence on export of intracellular pigments in Monascus fermentation

SummaryIn this study, perstractive fermentation of intracellular Monascus pigments in nonionic surfactant micelle aqueous solution had been studied. The permeability of cell membrane modified by nonionic surfactant might have influence on the rate of export of intracellular pigments into its extracellular broth while nearly no effect on the final extracellular pigment concentration. However, the solubilization of pigments in nonionic surfactant micelles strongly affected the final extracellular pigment concentration. The solubilization capacity of micelles depended on the kind of nonionic surfactant, the super-molecule assembly structure of nonionic surfactant in an aqueous solution, and the nonionic surfactant concentration. Elimination of pigment degradation by export of intracellular Monascus pigments and solubilizing them into nonionic surfactant micelles was also confirmed experimentally. Thus, nonionic surfactant micelle aqueous solution is potential for replacement of organic solvent for perstractive fermentation of intracellular product.

QSPR modeling of nonionic surfactant cloud points: An update

Quantitative structure–property relationship (QSPR) models for the cloud points of nonionic surfactants were developed based on CODESSA descriptors. Essentials accounting for a reliable model were considered carefully. Four descriptors were selected by a generic algorithm (GA) method to link the structures of nonionic surfactants to their corresponding cloud-point values. The descriptors were also analyzed using principal component analysis (PCA). Nonlinear models based on support vector machine (SVM) and projection pursuit regression (PPR) were also developed. All models were validated in two ways, i.e., internal cross-validation (CV) and a test set. The results are discussed in light of the main factors that influence the property under investigation and its modeling. In addition, an independent external data set of 16 nonionic surfactants was used to check the generalization ability of the optimum model.

Effect of nonionic surfactants on structure, texture, and morphology of titania-doped YSZ

The effect of nonionic surfactant structure and concentration on the structural and textural properties, as well as on morphology of titania-doped YSZ (yttria-stabilized zirconia) (TYZ) prepared by the citrate polymeric method is investigated in order to design the optimal conditions for the synthesis of highly structured materials. The calcined powders were characterized by wide- and small-angle X-ray diffraction (wa-XRD and sa-XRD), N 2 adsorption–desorption, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Mesoporous ceramic materials have been obtained when 8 vol% alkyl poly(oxyethylene) surfactants were added in the reaction mixture, samples having a BET surface area of about 106 m 2 g −1.

Structure of Nonionic Surfactant (Glycerol α-Monomyristate) Micelles in Organic Solvents: A SAXS Study

In this paper we present the study of reverse micellar aggregates formed by glycerol alpha-monomyristate (C(14)G(1)) in different organic solvents. We have investigated the structure (mainly shape and size) of the monomyristin reverse micelles depending on alkyl chain length of the oils, temperature, and the surfactant concentration. Moreover, we present how addition of trace polar additives such as water or glycerol and the hydrophilic size of the surfactant affect the structure of the micelles. Monomyristin could not form any self-organized structure in nonpolar media at room temperature because of its smaller headgroup size and tends to separate from the nonpolar media. In dilute regions this surfactant forms a solid dispersion, which upon heating transforms into an isotropic reverse micellar solution. For the structural characterization of the reverse micelles formed at elevated temperatures, we have performed small-angle X-ray scattering (SAXS) measurements, and the data were analyzed utilizing the generalized indirect Fourier transformation (GIFT) method. The SAXS data have shown that the size of the reverse micelles increases with the alkyl chain length of oils and surfactant concentration but decreases with temperature. A dramatic growth to the micelles could be achieved when the hydrophilic size of the surfactant is increased. Furthermore, addition of trace water or glycerol induces a significant change in the structure of micelles in terms of a cross-section and maximum length. The added water tends to form a water pool in the micellar core and results in swollen micelles. Model-free cross-section analysis of the SAXS data provided complementary information on the structural parameters. Thus, the present study has highlighted the possible ways of controlling the structure, mainly the shape and the size of the inverse micelles.

Surface aggregate structure of nonionic surfactants on silica nanoparticles

The self-assembly of two nonionic surfactants, pentaethylene glycol monododecyl ether (C12E5) and n-dodecyl-{\ss}-maltoside ({\ss}-C12G2), in the presence of a purpose-synthesized silica sol of uniform particle size (diameter 16 nm) has been studied by adsorption measurements, dynamic light scattering and small-angle neutron scattering (SANS) using a H2O/D2O mixture matching the silica, in order to highlight the structure of the surfactant aggregates. For C12E5 strong aggregative adsorption onto the silica beads, with a high plateau value of the adsorption isotherm above the CMC was found. SANS measurements were made at a series of loadings, from zero surfactant up to maximum surface coverage. It is found that the spherical core-shell model nicely reproduces the SANS data up to and including the local maximum at q = 0.42 nm-1 but not in the Porod region of high q, indicating that the surface area of the adsorbed surfactant is underestimated by the model of a uniform adsorbed layer. A satisfactory representation of the entire scattering profiles is obtained with the model of micelle-decorated silica beads, indicating that C12E5 is adsorbed as spherical micellar aggregates. This behaviour is attributed to the high surface curvature of the silica which prevents an effective packing of the hydrophobic chains of the amphiphile in a bilayer configuration. For the maltoside surfactant {\ss}-C12G2 very weak adsorption on the silica beads was found. The SANS profile indicates that this surfactant forms oblate ellipsoidal micelles in the silica dispersion, as in the absence of the silica beads.

The influence of nonionic surfactant structure on the thermodynamics of anionic dye–cationic surfactant interactions in ternary mixtures

Anionic dye–cationic surfactant interaction was measured in a solution of a nonionic surfactant with a concentration greater than the critical micelle concentration using potentiometry. Two azo dyes namely, C.I. Acid Red 88 and C.I. Acid Orange 7, the cationic surfactant dodecyltrimethylammonium bromide and seven nonionic surfactants were studied. The use of ion-selective membrane electrodes for potentiometric titrations and the theoretical model chosen enabled two constants to be established: (i) the association constant, K 1, for the first association step in the formation of a complex between the anionic dye and cationic surfactant in the solution of the nonionic surfactant and (ii) the association constant, κ 1, for the first association step in the formation of the cationic surfactant–micelle of the nonionic surfactant complex. The thermodynamic parameters Δ G 1 0, Δ H 1 0, and Δ S 1 0 for these two steps were determined. The tendency to form dye–cationic surfactant complexes in a micellar solution of the nonionic surfactant decreases as the hydrophile–lipophile balance of the nonionic surfactant increases. This finding is in contrast to that obtained for the interactions between cationic and nonionic surfactants under the same conditions. An increase in the hydrophile–lipophile balance of the nonionic surfactant also reduced the Δ H 1 0 and Δ S 1 0 values for complex formation; the formation of the dye–cationic surfactant complexes in ternary mixtures is an entropy-driven process, regardless of nonionic surfactant structure.

Solubilization of nitrotoluenes in micellar nonionic surfactant solutions

A key factor in selecting surfactants to enhance chemical or biological transformation or physical removal of an organic pollutant from contaminated soil is knowledge of the pollutant's solubility behavior in the surfactant solution. This study investigated the influence of nonionic surfactant structure on the solubility of 4-nitrotoluene (NT), 2,3-dinitrotoluene, 2,4-dinitrotoluene, 2,6-dinitrotoluene, and 2,4,6-trinitrotoluene (TNT) at room temperature. For a series of alkyl phenol ethoxylates (Tergitol NP-8 to NP-40), decreasing the ethoxylate chain length increased the solubility of these nitrotoluenes by a factor of two or less in 10 g l(-1) surfactant solutions, but did not significantly change their molar solubilization ratios (MSR, e.g. 0.02 for TNT) or their micelle-water partition coefficients (K(m), e.g. 3.4 for TNT). For Tergitol NP-8 solutions ranging from 1.0 to 12.4 g l(-1), no enhancement in NT solubility was found, suggesting that the cloud point was reached. The MSRs for Tween 80 were higher than those of Tween 20 and the MSRs of Brij-58 were higher than those for Brij-35. When comparing solutes, NT had the highest solubility and MSR (0.28-0.41), while TNT had the lowest solubility and MSR (0.02-0.03). A linear relationship between K(m) values and octanol-water partition coefficients based on Triton X-100 predicted the logK(m) values within 0.5 of their measured values. A linear solvation free energy correlation for K(m) suggested the importance of solute volume and effective hydrogen bond basicity in the partitioning process while implying that the nitrotoluenes are solubilized in a polar portion of the micelle.