Cmc Values Research Articles

Amphiphilic pyrene-functionalized triazoliums for ATP recognition

Four pyrene functionalized triazolium salts with different lengths of alkyl tail from C4 to C16, i.e., PYTAZ-C4, PYTAZ-C8, PYTAZ-C12 and PYTAZ-C16, have been designed and synthesized for ATP recognition. It was revealed that the longer alkyl tail anchored receptors PYTAZ-C12 and PYTAZ-C16 exhibit low CMC values, and self-assemble nanoaggregation at low concentration in aqueous solution, which show a pyrene-based excimer emission at 496 nm. However, the shorter alkyl anchored receptors PYTAZ-C4 and PYTAZ-C8 give only the pyrene-based monomer emission at 380 nm at the test concentration of 10 μM in aqueous solution. Importantly, PYTAZ-C12 and PYTAZ-C16 exhibit a good fluorescence turn-on response toward polyphosphate anions, especially ATP, with the detection limits of 2.5 μM and 0.77 μM, respectively. Furthermore, probe PYTAZ-C16 was successfully used for fluorescence imaging of intracellular ATP in living cells.

Lipid bilayer permeabilities and antibiotic effects of tetramethylguanidinium and choline fatty acid ionic liquids

Ionic liquids (ILs) have been studied as potential components in antibiotic formulations based on their abilities to permeabilize and penetrate lipid bilayer, which correlate with their antibacterial effects. Fatty acid-based ILs (FAILs), in which the anion is a long-chain fatty acid, can permeabilize lipid membranes and have been used in biomedical applications since they have low human cell cytotoxicity. In this work we investigated the abilities of several different FAILs to permeabilize lipid bilayers and how that permeabilization correlates with antibacterial activity, cell membrane permeability, and cytotoxicity. The FAILs consisted of the cations tetramethylguanidinium (TMG) or choline combined with octanoate or decanoate. These FAILs were tested on model bilayer vesicles with three different lipid compositions for membrane permeabilization using a leakage assay. They were then tested for antibiotic and membrane permeabilization on bacterial and mammalian cells. The results show that while the octanoate-based FAILs do not form micelles and have low activities on vesicles and biological cells, the decanoate-based FAILs can permeabilize bilayers and have biological activities that correlate with the model vesicle results. The ILs with both cation and fatty-acid anion have strong activities while the decanoate alone has only minimal permeabilization and antibiotic activity. Membrane permeabilization occurs at FAIL concentrations below their CMC values which suggests that their mechanism of action may not involve micelle formation.

Wettability of a Polymethylmethacrylate Surface by Fluorocarbon Surfactant Solutions

To clarify the adsorption behavior of fluorocarbon surfactants on PMMA surfaces, the contact angles of two nonionic fluorocarbon surfactants (FNS-1 and FNS-2) and an anionic fluorocarbon surfactant (FAS) on polymethylmethacrylate (PMMA) surface were determined using the sessile drop method. Moreover, the effects of molecular structures on the surface tension, adhesion tension, solid–liquid interfacial tension, and adhesion work of the three fluorocarbon surfactants were investigated. The results demonstrate that the adsorption amounts for three fluorocarbon surfactants at the air–water interface are 4~5 times higher than those at the PMMA–solution interface. The three fluorocarbon surfactants adsorb on the PMMA surface by polar groups before CMC and by hydrophobic chains after CMC. Before CMC, FNS-2 with the smallest molecular size owns the highest adsorption amount, while FAS with large-branched chains and electrostatic repulsion has the smallest adsorption amount. After CMC, the three fluorocarbon surfactants form aggregates at the PMMA-liquid interface. FAS possesses the smallest adsorption amount after CMC. Besides, FNS-1 possesses a higher adsorption amount than FNS-2 due to the longer fluorocarbon chain and the lower CMC value of FNS-1. The adsorption behaviors of nonionic and anionic fluorocarbon surfactants on the PMMA surface are different. FAS forms interfacial aggregates before CMC, which may be attributed to the electrostatic interaction between the anionic head of FAS and the PMMA surface.

Cationic Gemini surfactants: a review on synthesis and their applications

Abstract The molecules of Gemini surfactants are dimeric and consist of two monomeric surfactant units linked by a spacer. Among them, cationic Gemini surfactants have a wide range of application in various industrial sectors such as pharmaceuticals, home and personal care, corrosion inhibition, etc. Various methods of synthesis have been investigated and tested for the synthesis of cationic Gemini surfactants. The surface properties of Gemini surfactants are highly dependent on various factors like spacer, headgroups, counterions, etc. The cationic Gemini surfactants have lower CMC values as compared to their monomeric analogues. This review highlights the different methods for the synthesis of cationic Gemini surfactants and the applications of these surfactants in different fields are presented.

Aggregation behavior of newly synthesized Gemini cationic surfactants in absence and in presence of different inorganic salts in 15% DMSO–water solvent

In this study, three Gemini cationic surfactants related to thiazol-2-amine with three hydrocarbon chain lengths including 3-hexylthiazol-3-ium (TAC6), 3-dodecylthiazol-3-ium (TAC12) and octadecylthiazol3-ium (TAC18) were prepared. Surfactant structures were confirmed with IR and 1HNMR Spectroscopies. Critical micelle concentrations for all surfactants in 15% DMSO-Water solvent were measured using conductometric, refractometric, and densitometric techniques. Thermodynamics parameters were computed and explained. Also, enhancing properties of all surfactants were indicated under the effect of two concentrations, 0.001 M and 0.01 M, of six inorganic salts including Cl−, Br−, I−, Co+2, Cu+2, and Mn+2 radicals using conductivity and refractive index measurements. All techniques used to measure critical micelles concentration showed a good convergence in measuring CMC values and the behavior of all surfactants in 15% DMSO-water solvent. Increasing the binding constant of the counter ion and association constant reflects the effect of hydrocarbon chain length increment on enhancing micelle formation, where TAC 18 was shown as the lowest CMC in all applied measurements. Modeling the density of all surfactant solutions under study indicates an increase in hydrophobic polarizability with an increase in the molecular weight of the surfactant. Inorganic salts decreased the CMC of all surfactants with the increase in Gibbs free energy of micellization which ensures easier formation of more stable micelles in the presence of a salt solution. The effect of salts on decreasing CMC for all surfactants under study was arranged in the following order: Mn+2 < Cu+2 < Co+2 for cationic radicals and I− < Br− < Cl− for anionic radicals.

Stimulation of cytochrome c oxidase activity by detergents

Cytochrome c oxidase (CytcO) is an integral membrane protein, which catalyzes four-electron reduction of oxygen linked to proton uptake and pumping. Amphipathic molecules bind in sites near the so-called K proton pathway of CytcO to reversibly modulate its activity. However, purification of CytcO for mechanistic studies typically involves the use of detergents, which may interfere with binding of these regulatory molecules. Here, we investigated the CytcO enzymatic activity as well as intramolecular electron transfer linked to proton transfer upon addition of different detergents to bovine heart mitoplasts. The CytcO activity increased upon addition of alkyl glucosides (DDM and DM) and the steroid analog GDN. The maximum stimulating effect was observed for DDM and DM, and the half-stimulating effect correlated with their CMC values. With GDN the stimulation effect was smaller and occurred at a concentration higher than CMC. A kinetic analysis suggests that the stimulation of activity is due to removal of a ligand bound near the K proton pathway, which indicates that in the native membrane this site is occupied to yield a lower than maximal possible CytcO activity. Possible functional consequences are discussed.

Photophysical Response of Propranolol in Biomimetic Micellar Media of Alkyltrimethylammonium Bromide Surfactants: Effect of pH and Alkyl Chain Length.

The photophysical behavior of a β-blocker drug propranolol (PPL) in micellar environments, formed by alkyltrimethylammonium bromide surfactants viz.; Cetyltrimethylammonium bromide (CTAB), Tetradecyltrimethylammonium bromide (TTAB), and Dodecyltrimethylammonium bromide (DTAB), has been investigated through fluorescence and UV-visible spectroscopic techniques at pH levels of 3.5, 7.4, and 10.4. The impact of pH on the critical micelle concentration (cmc) and micropolarity of micelles were assessed using pyrene as a photophysical probe. The cmc values were found to be lower at pH 10.4 compared to pH 7.4 and pH 3.5. Fluorescence emission intensities of PPL at 323nm, 338nm, and 352nm were significantly influenced by pH, hydrophobic alkyl chain length of surfactants, and their concentrations. Quenching experiments with Cetylpyridinium chloride (CpCl) indicated the localization of charged and uncharged forms of PPL within micelles, with quenching constant (Ksv) values dependent on alkyl chain length and pH. At pH < pKa, PPL is positioned near the Stern layer, whereas at pH 10.4, its naphthalene moiety resides near the hydrophobic micellar core. UV spectroscopy showed that the charged form of PPL interacted with micelles only above cmc, while the neutral form interacted even below the cmc. Density Functional Theory (DFT) reveals the HOMO of the surfactants to be localized on the hydrocarbon chains, and the LUMO localized around the quaternary ammonium unit. Upon complexation with PPL, both HOMO and LUMO shifted to the drug, thereby decreasing energy levels. The findings are explained based on weak noncovalent interactions, further supported and analyzed through Reduced Density Gradient (RDG) and Noncovalent Interaction (NCI) methods, confirming synergistic non-covalent interactions in surfactant-PPL complexes.

Presenting a new fluorescent probe, methyl(10-phenylphenanthren-9-yl)sulfane sensitive to the polarity and rigidity of the microenvironment: applications toward microheterogeneous systems.

A molecule, methyl(10-phenylphenanthren-9-yl)sulfane (MPPS), with a straightforward structure, has been synthesized, characterized, and explored as a new fluorescent probe for microheterogeneous systems. The photophysical properties of MPPS have been studied through experimental and theoretical calculations using the range-separated hybrid functional CAM-B3LYP in conjunction with a 6-311++g(d,p) basis set. Theoretical calculations show that the freely rotating phenyl ring forms a 94° dihedral angle with the phenanthrene ring in the ground state. Experimentally found two absorption bands correspond to the n → π* and π → π* transitions supported by the frontier molecular orbital calculations. Two excited singlet states, E-1 and E-2 (the former being more stable than the latter in the gas phase), exist with dihedral angles between the phenyl and phenanthrene rings as 142° and 133°, respectively, in the gas phase. Two emitting states in a condensed medium of varying polarities are supported by the steady-state fluorescence and fluorescence intensity decay data. Emission energies, fluorescence intensities, and excited singlet state lifetimes change with the polarity of the solvents. To support that the free rotation in the molecule is responsible for these changes, the fluorescence properties of another molecule, methyl(10-(o-tolyl)phenanthren-9-yl)sulfane (MTPS), with restricted rotation of the substituted benzene, i.e., o-tolyl ring have been studied. The fast-intensity decay component of MPPS is ascribed to the conformer in the E-1 state. The molecule has proved to be an excellent polarity probe explored to determine the critical micelle concentrations (cmc) values of different surfactants, which agree well with the literature reports. Different regions of binding isotherm (specific, non-cooperative, cooperative, and massive binding) of a gemini surfactant, 12-6-12,2Br- with bovine serum albumin (BSA) have been successfully demonstrated by the steady-state and time-resolved fluorescence and fluorescence anisotropic properties of MPPS. Docking results show that MPPS resides in the hydrophobic pocket of BSA. The fluorescence quenching of BSA by MPPS reveals the location of Trp residues of BSA. Thus, a polarity and molecular rigidity-sensitive fluorescent molecule, MPPS has been presented here that can potentially be used to monitor the changes in the microenvironment of biomolecules in different processes.

New piperidinium surfactants with carbamate fragments as effective adjuvants in insecticide compositions based on imidacloprid.

Surfactants, particularly non-ionic ones, are widely used as adjuvants in pesticide formulations due to their ability to maintain pesticide effectiveness without changing solution properties, such as pH. While non-ionic surfactants are generally low-toxic, stable, and excellent dispersants with high solubilization capabilities, they may be less effective than cationic surfactants, which offer superior surface activity, transport properties, and antimicrobial action. This study investigates the efficacy of new piperidinium surfactants with carbamate fragments as adjuvants in insecticide formulations containing imidacloprid. The efficacy of these formulations is being assessed against greenhouse whitefly, a pest known to harm cultivated and ornamental flowering plants. The aggregation behavior of piperidinium surfactants containing carbamate fragments was investigated, and their wetting effect was evaluated. Synthesized surfactants have lower CMC values compared to their methylpiperidinium analogue. The effect of piperidinium surfactants on the insecticide concentration on the surface and inside tomato leaves was assessed using spectrophotometric methods. It was found that the introduction of piperidinium surfactants with carbamate fragment at a concentration of 0.1% wt. allows for decrease in lethal concentration of imidacloprid up to 10 times, thereby testifying the marked increase in the effectiveness of imidacloprid against the greenhouse whitefly insect pest (Trialeurodes vaporariorum). It was shown that the main factors responsible for the enhanced efficacy of the insecticide were the ability of the surfactant to increase the concentration of imidacloprid on the leaf surfaces and improve their penetration into the plant. The presented work employed a comprehensive approach, which significantly increases the generalizability of the results obtained and provides the ability to predict the effect and target selection of adjuvants. © 2024 Society of Chemical Industry.

Thermodynamic characteristics and aggregation behavior of surface active ionic liquids in presence of vitamin B7 (biotin)

Abstract This study investigated the influence of vitamin B7 (biotin) at different concentrations (0.1, 0.3 and 0.5) mM on the micellisation behaviour of three different ionic liquids with different cationic headgroups, namely N-methylmorpholinium bromide [Mor1,12][Br], N-dodecyl-N-methylpyrrolidinium bromide [Pyrr1,12][Br], and 1-dodecyl-3-methylimidazolium bromide [C12mim][Br], at four different temperatures (298.15, 303.15, 308.15, and 313.15) K using electrical conductivity and surface tension measurements. The evaluated CMC values for the studied system were used to obtain information about the colloidal behavior of the ionic liquids in the presence of biotin. The different thermodynamic parameters were studied. Tensiometry was used to determine the interfacial properties. The parameters obtained were used to study the different types of interactions for micelle formation. The main objective of studying these interactions is to further utilize this type of mixture in pharmaceutical industry, medicinal chemistry, and bio industry.

Impacts of composition of short chain alcohols/ urea and temperature change on the interaction of polyvinyl alcohol and sodium dodecyl sulfate: Conductivity and DFT investigations

Herein, the conductivity measuring approach was used to investigate the aggregation of polyvinyl alcohol (PVA) with sodium dodecyl sulphate (NaDS) in H2O and H2O + alcohols (EtOH,1-PrOH, 2-PrOH)/ urea environments at various temperatures. The extent and nature of interaction between NaDS and PVA has been characterized from the achieved micellar parameters and energetics of the aggregation process. The micelle development has been characterized from the break point achieved in the conductivity vs. conc. of NaDS plots. At 303.15 K, the single CMC values of the NaDS + PVA mixture were decreased with increasing the amount of PVA (<0.5 % (w/w) PVA) while two CMC values were acquired at 0.5 % (w/w) PVA. The CMC values have been observed to change significantly with the concentrations of alcohols while an increasing trend in the CMC values has been detected in alcohols media above 6 % (w/w) composition. In water and aq. EtOH/urea solutions, the CMC values initially decline, reaches its lowest point, and then increases when the temperature is increased. In aq. 1-PrOH and 2-PrOH solutions, the CMC values demonstrate the enhancing fashion with increasing temperature. In all cases, negative ∆Gmo values were found, indicating spontaneous aggregation phenomena. The measurements of ∆Hmo and ∆Smo indicate that the PVA molecule interacts with NaDS through ion-dipole and hydrophobic interactions. Furthermore, compensation temperature (Tc) and intrinsic enthalpy gain (∆Hm0,*) for the studied system were measured and described with proper reasoning. In addition, the properties of complex formation and structural analysis, band gaps analysis, chemical hardness and UV-Vis spectral study of the NaDS, PVA, and NaDS + PVA mixed system with and without additive have been explored by using DFT technique.

New Cationic Gemini Surfactants and Their Use as Dispersants in Oil-in-Water (O/W) Emulsions

In the current research, two types of new cationic gemini surfactants with different spacers (aromatic and heterocyclic) derived from epichlorohydrine were prepared. The prepared compounds were characterized using FTIR and 1H-NMR spectroscopy. Then the value of critical micelle concentration CMC was calculated using the electrical conductivity and preparing a series of molar concentration of the new surfactants, as well as calculating the balance value between the hydrophilic and hydrophobic (lipophilic) HLB groups. Cationic gemini surfactants were tasted at different concentration 20-40 ppm by preparing dishes for oil-in-water emulsions determine their dispersion efficiency. It was observed that the dispersant containing the heterogeneous ring (MS1) was more efficiently dispersed than the surfactant containing the aromatic ring (MS2) in the presence of the same hydrocarbon chain and at a concentration of 40 ppm.

Volumetric, compressibility and viscometric studies on intermolecular interactions of NaC and NaDC with Emtricitabine and Lamivudine in aqueous medium at (298.15–313.15) K

Bile salts are bio-compatible natural amphiphiles having a significant role in pharmaceutical field as a solubility and permeability enhancer and possess a great biological importance for release and transport of nutrients due to dynamic micellization behavior. Hence, to unfold the interactional mystery of drug − bile salt system in the field of anti-retroviral drugs, we have aimed to investigate solute–solute and solute–solvent interactions of bile salts (NaC and NaDC) with anti-HIV drugs (Emtricitabine and Lamivudine) by using various techniques like volumetry, compressibility, and viscometry at temperature range (298.15 K-313.15 K) with a regular variation of 5 K. Experimental density and speed of sound data have been used to evaluate various physicochemical parameters such as apparent molar volume (φv), isentropic compressibility (κs), and apparent molar adiabatic compression (φκ). The CMC values of bile salts in pure water and aqueous solution of ECT and LMV at 298.15 K have also been evaluated from speed of sound data which corroborate well with our earlier conductivity study on these surfactants. The trends of φv, κs and φκ values for both NaC and NaDC with temperature and in presence of drugs (ECT/LMV) indicate strong solute–solvent interactions in studied system. The results are elucidated in terms of electrostatic and hydrophilic-hydrophobic interactions in bile salt-drug-water system which is confirmed by co-sphere overlap model. Comparatively, NaC offers strong interactions with both drugs due to more hydrophilic character than NaDC. Similarly, out of ECT and LMV, ECT shows strong solute–solvent interactions with both bile salts due to more hydrophilic character than LMV. Relative viscosity parameter (ηr) determined from viscosity measurements further supports above results. This interactional knowledge of bile salts with ECT and LMV would be beneficial to develop a better mechanism in pharmacy for enhancing efficacy and permeability of anti-HIV drugs by using bile salts as a drug delivery agent.

Adsorption and Aggregation Behaviors of Oleyl Alcohol-Based Extended Surfactant and Its Mixtures.

An oleyl alcohol-based extended surfactant, sodium oleyl polyethylene oxide-polypropylene oxide sulfate (OE3P3S), was synthesized and identified using FT-IR and 1H NMR. The adsorption and aggregation behaviors of OE3P3S and its mixture with cationic surfactant alkyltrimethylammoniumbromide (ATAB) were investigated under different molar ratios. The static surface tension analysis indicated that the critical micellization concentration (cmc) and the critical surface tension (γcmc) of OE3P3S were 0.72 mmol/L, and 36.16 mN/m, respectively. The cmc and γcmc values of the binary system were much lower than that of the individual component. And the cmc values of OE3P3S/ATAB = 6:4 mixtures decreased with an increase in the chain length of the cationic surfactant in the binary system. It was found from the dynamic surface tension that there was a slower diffusion rate in the binary system compared to the pure surfactant, and the adsorption processes for OE3P3S/ATAB = 6:4 were mixed diffusion-kinetic adsorption mechanisms. With a combination of DLS data and TEM measurements, formations of vesicles in OE3P3S/ATAB = 6:4 solutions appeared to occur at a concentration of 0.05 mmol/L. By studying the formation of liquid crystal structures in an emulsion prepared with OE3P3S as the surfactant, it was found that the oil-in-water emulsion is birefringent with a Maltese cross texture, and the rheological properties revealed its predominant viscoelastic behavior and shear thinning properties.

Synergistic effects of nonionic surfactants ethoxylated alkylamines and sodium dodecyl sulfate in mixed systems

HypothesisIn general, the performance of surfactant hybrid systems is better than that of single surfactants, so surfactant hybrid systems are widely used in various industries. As a very important class of nonionic surfactants, ethoxylated alkylamines have been widely used in industries such as washing, coating, and pesticide, but little research has been conducted on their mixed systems. In order to improve the utilization efficiency of surfactants and reduce wastage, the surface properties and aggregation behavior of ethoxylated alkylamine mixed systems should be further explored. ExperimentIn this study, the nonionic surfactant ethoxylated dodecylamine (AC-1202) and the anionic surfactant sodium dodecyl sulfate (SDS) were used to form a mixed system. The static surface tension and interaction parameters of the mixed system under the influence of inorganic salt ions were investigated using a KRÜSS K12 surface tensiometer. The diffusion process of the mixed system was investigated using a KRÜSS bubble pressure tensiometer. At the same time, the aggregate behavior of the mixed system was studied by particle size analyzer. In addition, the contact angle and rheological properties of the mixed solution were also investigated. FindingsThe SDS/AC-1202 mixture system formed a synergistic effect that could reduce the CMC value to 24.20 mN/m and the CMC value was as low as 22.89 mN/m after the addition of inorganic salts. The mixed system conforms to the kinetic mechanism of mixing and diffusion and the Ostwald de model for non-Newtonian fluids. Finally, there is a good aggregation pattern in the mixed system, and the stronger synergistic effect will lead to the reduction of the average particle size of the mixture to 45.41 nm.

Optimizing Recovery of Fracturing Fluid in Unconventional and Tight Gas Reservoirs Through Innovative Environmentally Friendly Flowback Additives

Hydraulic fracturing, a method used to stimulate oil and gas from shale and tight formations, faces challenges like fluid blockage and fast declining oil or gas production rates due to the significant impact of capillary forces on water retention. To address this, surfactants and microemulsions are commonly employed as flowback additives to reduce surface and interfacial tension, enhancing water recovery during hydraulic fracturing. The effectiveness of flowback additives is highly impacted by harsh subsurface conditions, such as high salinity and high temperature. This study aims to assess the performance and effectiveness of methylimidazolium chloride-based ionic liquids as flowback additives at high salinities and temperatures.Different experimental analysis were conducted to screen different concentrations of methylimidazolium chloride-based ionic liquids (X1, X2, and X3). Surface tension measurements were conducted to estimate the critical micelles concentrations. A spinning drop tensiometer (SDT) was utilized to measure interfacial tension, in addition, contact angle measurements were used to evaluate the impact of the flowback additive on the wettability and the displacing behavior. Seawater was used as the base fracturing fluid with a salinity of 57,000 ppm and temperatures up to 90°c for all experiments. Coreflood experiments were conducted using tight formations to evaluate the regained hydrocarbon permeability and the fracturing fluid recovery in the presence of flowback additives.Various formulations, with surface tension values ranging from 30 to 45 mN/m and CMC values between 0.5 and 1 gallon per thousand units (gpt), were examined. The lowest interfacial tension value, notably 3 mN/m, was achieved with the X3 formulation. Ionic liquids demonstrated favorable surface tension reduction, where longer carbon chains led to lower values. Introducing diverse ions, especially divalent ions, enhanced the performance of ionic liquids. Interfacial tension measurements indicated a significant reduction with the addition of X3 to both 5 wt% KCl and the fracturing base fluid. Contact angle measurements revealed a shift towards greater water-wettability after treating the rock with flowback additives. Moreover, the use of ionic liquids improved permeability by 25%, enhancing fluid recovery to around 56%.According to our results, methylimidazolium chloride-based ionic liquids can be used as environmentally friendly flowback additives, especially in harsh conditions of high temperature and high salinity where the conventional additives are not suitable. This will contribute to the development of more sustainable and environmentally conscious practices in hydraulic fracturing operations. Ultimately, the utilization of these additives can help mitigate water blockage, reduce formation damage, and enhance shale gas production.

Novel approaches to monitoring the formation of self-assembled colloids composed of cationic surfactants and alginate polysaccharide

In actual work, the self-assembly process of alginate (Alg) polysaccharide having low molecular weight (240 kDa) with cationic surfactants from the family of trimetylammonium bromide (TAB) derivatives was investigated at wide polysaccharide/surfactant molar ratio range through the interpretation of the formation of non-aggregated colloidal complexes.On one hand, the critical micelle concentration (cmc) values of the studied TAB surfactants having C12C18 chain length were determined and published for the first time in phosphate buffer solution. In addition to the applied conventional measurement procedures like tensiometry, light scattering, calorimetry, and equilibrium dialysis-based methods, the applicability of streaming potential technique was also demonstrated for the first time for these types of systems to gain a deeper insight into the formation process of the complexes built up by biocompatible polysaccharides and cationic surfactants. Through the interpretation of the change of the streaming potential values as a function of increasing surfactant's concentration it was clearly highlighted that both the individual and cooperative binding process of the surfactants can be clearly identified followed by the aggregation of the polysaccharide-surfactant colloidal complexes and the formation of surfactant micelles in the bulk dispersion.

Influence of pH on spectroscopic and interfacial features of phenol in aqueous cetrimonium bromide solutions of different concentrations

Phenol is an aromatic compound with toxic effects on the environment and living organisms. Cetrimonium bromide (CTAB) is a cationic, quaternary ammonium surfactant, constituent in industrial formulations, and is employed for solubilization as well as removal of pollutants. This study explores the impact of pH on the behavior of phenol in the micellar solution of CTAB via UV–Visible spectroscopy and surface tension measurements at room temperature. Binding coefficient (Kb), free energy change of binding (ΔGb), change in molar absorptivity (Δε), partition coefficient (Kc), free energy change of partitioning (ΔGp) and number of molecules per micelle (n) were determined at different pH. Results showed that phenol exhibits no appreciable interaction with the CTAB, however phenolate ions have the tendency to bind with CTAB micelles and penetrate in the palisade layer of CTAB.Surface properties such as surface excess (τmax), minimum area per molecule (Amin), packing parameter (P), surface area per head group (as), free energy changes of micellization (ΔGm), adsorption ΔGads, and transfer (ΔGtrans), and surface pressure (Π) for CTAB, and phenol in CTAB solutions were also determined. Interfacial studies supported the role of phenol in facilitating micellization of CTAB thermodynamically and hence a fall in CMC values of CTAB except for pH 7.11. Calculated interfacial parameters established the influence of phenol over rearrangement and surface adsorption of CTAB molecular ions at air/water interface. Surface tension results also showed that unionized phenol molecules have low surface activity (62.23mN/m), but when phenol is ionized into phenolate ion surface dramatically increased (44.17 mN/m).

A novel pectin polysaccharide from vinegar-baked Radix Bupleuri absorbed by microfold cells in the form of nanoparticles

Polysaccharides of vinegar-baked Radix Bupleuri (VBCP) have been reported to exhibit liver-targeting and immunomodulatory activities through oral administration, but the absorption behavior and mechanism of VBCPs have not been extensively studied. In this study, a novel HG type pectin polysaccharide, VBCP1–4, with a high molecular weight of 2.94 × 106 Da, was separated from VBCP. VBCP1–4 backbone was contained 1,4-α-D-GalpA, 1,4-α-D-GalpA6OMe, 1,3,4-α-D-GalpA and 1,2,4-α-D-Rhap. The branches were mainly contained 1,5-α-L-Araf, 1,3,5-α-L-Araf, t-α-L-Araf and t-α-D-Galp, which linked to the 3 position of 1,3,4-α-D-GalpA and the 4 position of 1,2,4-α-D-Rhap. VBCP1–4 could self-assemble to nanoparticles in water, with CMC values of 106.41 μg/mL, particle sizes of 178.20 ± 2.82 nm and zeta potentials of −23.19 ± 1.44 mV. The pharmacokinetic study of VBCP1–4, which detected by marking with FITC, revealed that it could be partially absorbed into the body through Peyer's patches of the ileum. In vitro absorption study demonstrated that VBCP1–4 was difficult to be absorbed by Caco-2 cell monolayer, but could be absorbed by M cells in a time and concentration dependent manner. The absorption mechanism was elucidated that VBCP1–4 entered M cells through clathrin-mediated endocytosis in the form of nanoparticles. These findings provide valuable insights into the absorption behavior of VBCP and contribute to its further development.

Preparation, Characterization, and Hepatoprotective Activity Evaluation of Quercetin-loaded Pluronic® F127/Chitosan-Myristic Acid Mixed Micelles.

Quercetin (QTN) is a flavonol antioxidant found in foods, medicinal plants, fruits, vegetables, and beverages. QTN oral consumption produces several biological effects, including antioxidant, cardioprotective, anti-apoptotic, anti-cancer, neuroprotection, anti-hypertensive, and chemo preventive. The study aimed to prepare Pluronic®F127/chitosan-myristic acid copolymer (PF127/C-MAc)-based mixed micelles (QTN MM) to improve the biopharmaceutical and hepatoprotective potential of QTN. QTN MM was developed employing thin-film hydration and optimized using full factorial design (FFD). Optimized QTN MM was analyzed using scanning electron microscopy (SEM), differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FT-IR), powder x-ray diffractometry (PXRD), in vitro dissolution, ex vivo permeation, and in vivo antioxidant activity in carbon tetrachloride (CCL4)-induced albino rats. PF127/C-MAc ratio (1:1) with CMC value ~ 5 μg/mL showed the suitability for MM. Characterization supported the formation of MM. QTN MM revealed prominent encapsulation efficiency and drug loading of about ~ 95.10% and ~ 12.28% w/w, respectively. MM spherical shape of QTN with a smaller particle size of ~ 34.08 nm and a higher zeta potential of ~ 36.24 nm indicated excellent physical stability. Dissolution and ex vivo permeation results revealed higher dissolution and permeation of QTN MM compared to QTN and PM. In vivo antioxidant activity suggested that QTN MM at (~ 20 mg/kg, p.o.) restored the enhanced marker enzyme level compared to QTN. The findings demonstrate that developed QTN MM could be used as an alternative nanocarrier to increase the biopharmaceutical and hepatoprotective potential of QTN and other flavonoids.