Dicationic Gemini Surfactants Research Articles

The Interaction of a Gemini Surfactant with a DNA Quadruplex.

DNA secondary structures are stabilized by mono- and divalent cations. To examine the stability of the DNA quadruplex formed from (TTAGGG)4, its interaction with a dicationic Gemini surfactant in standard phosphate buffer was investigated. The Gemini surfactant begins to form micelles in buffer at a cmc (critical micelle concentration) of 1.5 mM. In this study, solutions of DNA were prepared in buffer with surfactant concentrations ranging from 0.0 to 3.0 mM, i.e., above and below the cmc of the surfactant. In all samples of DNA and surfactant, a precipitate formed. The fraction of DNA precipitated depends upon both the initial DNA concentration and the initial concentration of the surfactant. In those samples where the DNA did not totally precipitate, the residual DNA assumed a quadruplex conformation. It was determined that two surfactant molecules per DNA phosphate are needed to completely precipitate all of the DNA in a particular sample. An estimated apparent K sp for the DNA:surfactant complex was determined.

Synthesis, Properties, and Biomedical Application of Dicationic Gemini Surfactants with Dodecane Spacer and Carbamate Fragments.

A synthesis procedure and aggregation properties of a new homologous series of dicationic gemini surfactants with a dodecane spacer and two carbamate fragments (N,N'-dialkyl-N,N'-bis(2-(ethylcarbamoyloxy)ethyl)-N,N'-dimethyldodecan-1,6-diammonium dibromide, n-12-n(Et), where n = 10, 12, 14) were comprehensively described. The critical micelle concentrations of gemini surfactants were obtained using tensiometry, conductometry, spectrophotometry, and fluorimetry. The thermodynamic parameters of adsorption and micellization, i.e., maximum surface excess (Гmax), the surface area per surfactant molecule (Amin), degree of counterion binding (β), and Gibbs free energy of micellization (∆Gmic), were calculated. Functional activity of the surfactants, including the solubilizing capacity toward Orange OT and indomethacin, incorporation into the lipid bilayer, minimum inhibitory concentration, and minimum bactericidal and fungicidal concentrations, was determined. Synthesized gemini surfactants were further used for the modification of liposomes dual-loaded with α-tocopherol and donepezil hydrochloride for intranasal treatment of Alzheimer's disease. The obtained liposomes have high stability (more than 5 months), a significant positive charge (approximately + 40 mV), and a high degree of encapsulation efficiency toward rhodamine B, α-tocopherol, and donepezil hydrochloride. Korsmeyer-Peppas, Higuchi, and first-order kinetic models were used to process the in vitro release curves of donepezil hydrochloride. Intranasal administration of liposomes loaded with α-tocopherol and donepezil hydrochloride for 21 days prevented memory impairment and decreased the number of Aβ plaques by 37.6%, 40.5%, and 72.6% in the entorhinal cortex, DG, and CA1 areas of the hippocampus of the brain of transgenic mice with Alzheimer's disease model (APP/PS1) compared with untreated animals.

Self-Assembled Surfactant-Polyoxovanadate Soft Materials as Tuneable Vanadium Oxide Cathode Precursors for Lithium-Ion Batteries.

The mixing of [V10 O28 ]6- decavanadate anions with a dicationic gemini surfactant (gem) leads to the spontaneous self-assembly of surfactant-templated nanostructured arrays of decavanadate clusters. Calcination of the material under air yields highly crystalline, sponge-like V2 O5 (gem-V2 O5 ). In contrast, calcination of the amorphous tetrabutylammonium decavanadate allows isolation of a more agglomerated V2 O5 consisting of very small crystallites (TBA-V2 O5 ). Electrochemical analysis of the materials' performance as lithium-ion intercalation electrodes highlights the role of morphology in cathode performance. The large crystallites and long-range microstructure of the gem-V2 O5 cathode deliver higher initial capacity and superior capacity retention than TBA-V2 O5 . The smaller crystallite size and higher surface area of TBA-V2 O5 allow faster lithium insertion and superior rate performance to gem-V2 O5 .

Self‐Assembled Surfactant‐Polyoxovanadate Soft Materials as Tuneable Vanadium Oxide Cathode Precursors for Lithium‐Ion Batteries

AbstractThe mixing of [V10O28]6− decavanadate anions with a dicationic gemini surfactant (gem) leads to the spontaneous self‐assembly of surfactant‐templated nanostructured arrays of decavanadate clusters. Calcination of the material under air yields highly crystalline, sponge‐like V2O5 (gem‐V2O5). In contrast, calcination of the amorphous tetrabutylammonium decavanadate allows isolation of a more agglomerated V2O5 consisting of very small crystallites (TBA‐V2O5). Electrochemical analysis of the materials’ performance as lithium‐ion intercalation electrodes highlights the role of morphology in cathode performance. The large crystallites and long‐range microstructure of the gem‐V2O5 cathode deliver higher initial capacity and superior capacity retention than TBA‐V2O5. The smaller crystallite size and higher surface area of TBA‐V2O5 allow faster lithium insertion and superior rate performance to gem‐V2O5.

Sequential chiral induction between organic and inorganic supramolecular helical assemblies for the in situ formation of chiral carbon dots.

Self-organised helical bilayers of dicationic gemini surfactants confined in helical silica nanospace were transformed in situ to carbon dots (CDots) via pyrolysis. These water-dispersible CDots exhibit electronic absorption spanning the UV and visible range and possess symmetrical circular dichroism (CD) signals, the sign of which depends on the handedness of the helices.

A UV–visible and conductometric studies on the analyses of valine and ninhydrin reaction in aqueous-surfactant solutions of dicationic geminis (n-s-n type)

The influence of surfactants (represent the respective length of alkyl and tail chain referred to as gemini) was investigated on rate constant (kψ) of valine (Val) and ninhydrin. Also, the effect of other experimental parameters that includes reactant’s concentration (Val and ninhydrin), pH and temperature was performed and examined. Via UV–visible method, the absorbance of different solutions was recorded at fixed time intermissions and kψ was estimated by employing a computer-based procedure. The values ofkψ obtained at varied concentrations of gemini n-s-n (n = 16; s = 4–6) surfactants show an infrequent behavior (plotted askψvs. [gemini]). In the plot, kψ data rises gently at surfactant concentration far smaller related to cmc-value (Segment I) and formerly attains virtually unaffected behavior (Segment II, up to 400 × 10-5 mol dm−3). To end, we perceive a quick variation in kψ beyond 400 × 10-5 mol dm−3 (Segment III). Dicationic geminis improve the study, excellently, at [n-s-n] slighter than cmc over monomeric CTAB. However, quantitative treatment of such results achieved in dicationic gemini surfactant solutions was made by an appropriate model of micellar activity recognized as pseudo phase. Critical micelle concentration (cmc) of dicationic geminis (n-s-n type) with reactants has been determined at two different temperatures 303 K and 353 K using conductometric analysis. A reasonable reaction mechanism concerning the present study is provided. Additionally, some other reaction factors (binding and rate constants) were evaluated and discussed.

Effect of dicationic gemini surfactants on the rate of reaction between ninhydrin and arginine

Effect of dicationic gemini surfactants on the rate of reaction between ninhydrin and arginine

Cooperative interaction between organic and inorganic moieties in hybrid silica nanohelices for enantioselective interaction.

Hybrid nanometric helical structures formed by the molecular assemblies of dicationic gemini surfactants with tartrate counterions covered with helical silica walls interact differently with matching or mismatching enantiomers of the tartrate. The difference of the interaction is based on the cooperativity between the chiral crystalline gemini surfactant molecular organization/conformation and the rigid chiral nanospace formed by the helical silica wall.

Evaluation of Clay Hydration and Swelling Inhibition Using Quaternary Ammonium Dicationic Surfactant with Phenyl Linker.

Water-based drilling fluids are extensively used for drilling oil and gas wells. However, water-based muds cause clay swelling, which severely affects the stability of wellbore. Due to two adsorption positions, it is expected that cationic gemini surfactants can reduce the clay swelling. In this work, quaternary ammonium dicationic gemini surfactants containing phenyl linkers and different counterions (Cl− and Br−) were synthesized, and the effect of variation in counterions on swelling and hydration properties of shales was studied. Numerous water-based drilling fluid formulations were prepared with different concentrations of surfactants to study the swelling inhibition capacity of surfactants. The performance of surfactant-containing drilling muds was evaluated by comparing them with base drilling mud, and sodium silicate drilling mud. Various experimental techniques were employed to study drilling mud characteristics such as rheology and filtration. The inhibition properties of drilling mud formulations were determined by linear swelling experiment, capillary suction time test, particle size distribution measurement, wettability measurements, and X-ray Diffraction (XRD). Experimental results showed that surfactant-based formulation containing bromide counterion exhibited superior rheological properties as compared to other investigated formulations. The filtration test showed that the gemini surfactant with chloride counterion had higher filtrate loss compared to all other formulations. The bentonite swelling was significantly reduced with increasing the concentration of dicationic surfactants as inhibitors, and maximum reduction in the linear swelling rate was observed by using a formulation containing surfactant with chloride counterion. The lowest capillary suction timer (CST) was obtained in the formulation containing surfactant with chloride counterion as less CST indicated the enhanced inhibition capacity. The particle size measurement showed that average bentonite particle size increased upon the addition of surfactants depicting the inhibition capacity. The increase in basal spacing obtained from XRD analysis showed the intercalation of gemini surfactants in interlayers of bentonite. The contact angle measurements were performed to study the wettability of the bentonite film surface, and the results showed that hydrophobicity increased by incorporating the surfactants to the drilling fluid.

Ammonium Gemini Surfactants Form Complexes with Model Oligomers of siRNA and dsDNA.

Dimeric cationic surfactants (gemini-type) are a group of amphiphilic compounds with potential use in gene therapy as effective carriers for nucleic acid transfection (i.e., siRNA, DNA, and plasmid DNA). Our studies have shown the formation of lipoplexes composed of alkanediyl-α,ω-bis[(oxymethyl)dimethyldodecylammonium] chlorides and selected 21-base-pair nucleic acid (dsDNA and siRNA) oligomers. To examine the structure and physicochemical properties of these systems, optical microscopy, circular dichroism spectroscopy (CD), small-angle X-ray scattering of synchrotron radiation (SR-SAXS), and agarose gel electrophoresis (AGE) were used. The lengths of spacer groups of the studied surfactants had a significant influence on the surfactants’ complexing properties. The lowest charge ratio (p/n) at which stable lipoplexes were observed was 1.5 and the most frequently occurring microstructure of these lipoplexes were cubic and micellar phases for dsDNA and siRNA, respectively. The cytotoxicity tests on HeLa cells indicated the non-toxic concentration of surfactants to be at approximately 10 µM. The dicationic gemini surfactants studied form complexes with siRNA and dsDNA oligomers; however, the complexation process is more effective towards siRNA. Therefore these systems could be applied as transfection systems for therapeutic nucleic acids.

Interaction of ninhydrin with zinc(II) complex of tryptophan in the three dicationic gemini surfactants

Present work concerns with the interaction of ninhydrin with zinc(II) complex of tryptophan ([Zn(II)-Trp]+) in the three dicationic gemini surfactant systems. To record critical micellar concentration (CMC) and absorbance, we have used Systronics conductivity meter and UV-visible spectrophotometer, respectively. Experiment opens up the fractional- and first-order paths in ninhydrin and complex, respectively. Gemini micellar medium is found more superior over aqueous medium. Rate constant (kψ) vs. [gemini] plot shows the unusual role of geminis on kψ. kψ increases with gemini concentration (at concentrations lower than the CMC, part I) and leveling-off regions obtain (concentration up to 400 × 10−5 mol dm−3, part II). Characteristics of part I and part II are just the same as that of conventional surfactant. Later, gemini produces a third region of increasing kψ at higher concentrations ([gemini] > 400 × 10−5 mol dm−3, part III). Detail and systematic elucidation about the effect of surfactants are mentioned and discussed in the text. Binding constants (KS for [Zn(II)-Trp]+ and KN for ninhydrin) and rate constant (km in geminis) were determined by nonlinear least squares regression technique. The kinetic results acquired can reasonably be interpreted by pseudo-phase model of surfactant micelles.

Multipotent stem cell-derived retinal ganglion cells in 3D culture as tools for neurotrophic factor gene delivery system development

Non-viral neurotrophic factor (NF) gene therapy is a new paradigm in glaucoma treatment with the potential for neuroprotection and regeneration of damaged retinal ganglion cells (RGCs). To improve nanoparticle gene delivery systems and generate a suitable RGC cell model to facilitate in vitro investigations, we have developed mouse multipotent retinal stem cell (MRSC)-derived RGCs (XFC-3 cells) that express key RGC characteristics as demonstrated through biomarker expression profiling and stimuli-inducible neurite extension evaluation. Dicationic gemini surfactant-, single-walled carbon nanotube-, and K2-lipopolyamine polymer-based gene delivery systems were formulated and evaluated in three-dimensional (3D) A7/XFC-3 and XFC-3/XFC-3 co-cultures to validate the model for transfection efficiency (TE) and brain-derived neurotrophic factor (BDNF) bioactivity measurements, which helped identify the K2-NPs as having high TE (63.1% ± 1.4%) and high cell viability (94.4% ± 0.4%). Overall, XFC-3 cells are suitable for the construction of 3D in vivo-like tissue models and enable the screening of RGC-aimed gene delivery systems for neuroprotective treatment of glaucoma.

Synthesis and Characterization of Dicationic Gemini Surfactant Micelles and their Effect on the Rate of Ninhydrin–Copper-Peptide Complex Reaction

Abstract Herein, we have synthesized and characterized dicationic Gemini surfactants. The effect of their micelles on the rate constant of ninhydrin with [Cu(II)-Gly-Gly]+ complex reaction was investigated under pseudo-first-order-conditions. Experiments were carried out by means of spectrophotometry. First- and fractional-order dependencies on [Cu(II)-Gly-Gly]+ and ninhydrin, respectively, were found. The results indicated that the efficiency of micellar catalysis by Gemini surfactants was significantly higher as compared to single-chained surfactant cetyltrimethylammonium bromide, CTAB. The Gemini surfactant produces a catalytic effect and leveling-off regions (just like CTAB) on the reaction rate. Later, Gemini with higher concentrations gives a third region of increasing k ψ. The effect of surfactants was rationalized by hydrophobic and electrostatic interactions. The observed kinetic effects are explained by applying the Menger-Portnoy model.

Exploring the dicationic gemini surfactant for the generation of mesopores: a step towards the construction of a hierarchical metal–organic framework

The dicationic gemini surfactant cooperatively self-assembles with the Cu-BTC precursors to form a hierarchical microporous–mesoporous metal–organic framework.

In vitro disintegration of goat brain cystatin fibrils using conventional and gemini surfactants: Putative therapeutic intervention in amyloidoses

Many protein misfolding diseases in mammalian system are characterised by the accumulation of protein aggregates in amyloid fibrillar forms. Several therapeutic approaches include reduction in the production of the amyloidogenic form of proteins, increase in the clearance rate of misfolded or aggregated proteins, and direct inhibition of the self-assembly process have been explained. One of the possible remedial treatments for such disorders may be to identify molecules which are capable of either preventing formation of fibrils or disintegrating the formed fibrils. In this work, we have studied the effect of conventional surfactants; sodium dodecylsulphate (SDS), cetyl trimethylammonium bromide (CTAB) and dicationic gemini (16-4-16) surfactant on the disintegration of the goat brain cystatin (GBC) fibrils above their critical micelle concentrations (CMC) using ThT fluorescence, CD, TEM, Congo red and turbidity approaches. The results obtained are significant and showing the best disintegrating potency on GBC fibrils with gemini surfactant. The outcome from this work will aid in the development and/or design of potential inhibitory agents against amyloid deposits associated with amyloid diseases.

Interaction between copper(II) complex of glycylphenylalanine and ninhydrin in aqueous–micellar solutions of gemini surfactants

In the present study, we have reported the interaction between copper(II) complex of glycylphenylalanine, [Cu(II)-Gly-Phe]+, and ninhydrin in aqueous–micellar solutions of gemini surfactants (16-s-16, s=4, 5, 6). The reaction showed first- and fractional-order dependencies, respectively, on [complex] and [ninhydrin]. The surfactants used in this reaction are a dicationic gemini and its catalytic behavior was also seen on the reaction rate. It is found that dicationic gemini surfactants are more effective than the respective monomeric surfactant (CTAB) with the same number of carbon atoms in the hydrophobic chain per hydrophilic head group. Moreover, while the typical rate constant (kΨ) increases and leveling-off regions, same as conventional monomeric surfactant CTAB (cetyltrimethylammonium bromide), are observed with geminis, the latter produced a third region of increasing kΨ at higher concentrations. The observed micellar catalysis is interpreted by the means of pseudo-phase model of the micelles (proposed by Menger and Portnoy and developed by Bunton). The values of thermodynamic parameters and binding constants were also evaluated by using the observed kinetic data.

Lipoplexes of dicationic gemini surfactants with DNA: Structural features of DNA compaction and transfection efficiency.

The internal structure of DNA lipoplexes with hydroxyethylated alkylammonium gemini surfactants (GS) with high transfection activity was studied by circular dichroism. It was shown that the efficiency of transfection of HEK293T cells with the pEGFP-N1 circular plasmid was different from zero only in the region of existence of chiral supramolecular DNA-GS complexes and reaches a maximum at concentrations at which the spontaneous aggregation of components is observed.

Self-aggregation of surfactant ethane-1,2-diyl bis(N,N-dimethyl-N-hexadecylammoniumacetoxy) dichloride: tensiometric, microscopic, and spectroscopic studies.

We have investigated the effect of salt additives (NaCl, Na₂SO₄, Na₃PO₄, NaTos, and NaAn) on the aggregation behavior of a cleavable biodegradable ester-bonded dicationic gemini surfactant, ethane-1,2-diyl bis(N,N-dimethyl-N-hexadecylammoniumacetoxy) dichloride (16-E2-16). A multitechnique approach employing tensiometry, fluorescence, proton magnetic resonance (¹H NMR), transmission electron microscopy (TEM), absorption spectrophotometry (UV), and Fourier transform infrared spectroscopy (FTIR) was utilized to probe physicochemical fluctuations. Appreciable changes were observed in various physicochemical parameters, viz., critical micelle concentration (CMC), surface excess concentration (Γ(max)), minimum area per headgroup (A(min)), free energy of micellization (ΔG(mic)°), free energy of adsorption (ΔG(ads)°), and aggregation number (N(agg)). Counter ions were found to affect through electrostatic and hydrophobic influence obeying the overall trend as NaAn > NaTos > Na₃PO₄ > Na₂SO₄ > NaCl. ¹H NMR, TEM, UV, and FTIR results reveal microstructure evolution and phase transitions. These results thus provide deeper insights in understanding of self-aggregation and microstructure evolution of biocompatible (green) aqueous systems of the gemini surfactant and their implications in the biomedical and pharmaceutical world, which could be helpful to improve their bioavailability and other biochemical aspects like drug delivery and gene transfection.

Study of the Interaction Between Promazine Hydrochloride and Surfactant (Conventional/Gemini) Mixtures at Different Temperatures

In the present paper, the micellization of an amphiphilic drug, promazine hydrochloride, and gemini surfactants (16-s-16) with s = 4–6 and the monomeric hexadecyltrimethylammonium bromide (CTAB) counterparts has been examined conductometrically in the pure and mixed states in aqueous solutions at different compositions and temperatures (298.15–308.15 K). Dicationic gemini surfactants provide much better environment for the micellization behavior than the corresponding monocationic counterpart CTAB. The critical micelle concentration (cmc) values are lower than the cmc for ideal mixing, cmc id, suggesting attractive interactions between the two components in mixed micelles. The micellar mole fractions of surfactants, evaluated by different models, show greater contributions of surfactants in mixed micelles and increase with increasing concentrations of these surfactants. The negative values of β suggest synergism in the mixtures, which is highly beneficial as it reduces the total amount of surfactants required in a particular application, leading to reductions of cost and environmental impact. Activity coefficients (f 1 and f 2) are always less than unity showing nonideality in the systems. The data have been also used for evaluation of thermodynamic parameters.

Self-assembly of symmetrical and dissymmetrical dicationic surfactants in the solid phase and in solution

The effect of the spacer structure (linear, cyclic, bicyclic) and dissymmetry of alkyl fragment in a series of dicationic gemini surfactants on the ability to form thermotropic liquid crystals and on the micellar properties was studied. Transitions crystal-thermotropic liquid crystals-isotropic solution were studied using differential scanning calorimetry and optical microscopy. The self-diffusion coefficients of micelles and monomers of the dicationic dialkyl derivatives of 1,4-diazabicyclo[2.2.2]octane in water were determined by pulsed field gradient NMR spectroscopy. The effect of the surfactant structure on the values of critical micelle concentrations, hydrodynamic radii, and aggregation numbers of micelles was analyzed.