Critical Micelle Concentration Values Research Articles

Aggregation and adsorption behavior of cobalt‐based metallosurfactant in water–ethylene glycol media forming worm‐like micelles

AbstractThe cobalt based metallosurfactant cis‐chlorobis(ethylenediamine)hexadecylaminecobalt(III) chloride (CHCC) has been prepared and well characterized by utilizing elemental analysis, NMR (1H, 13C), FT‐IR and UV–Vis spectroscopy. The CHCC metallosurfactant shows thermal stability up to 168°C. The micellization behavior of the synthesized CHCC metallosurfactant has been investigated systematically by the tensiometric, conductometric, and fluorescence techniques. The critical micelle concentration (cmc) values of CHCC have been determined in various water–ethylene glycol mixtures ranging from 0 to 100 weight % of ethylene glycol at 293.15, 298.15, 303.15, and 308.15 K. The physicochemical parameters namely counterion binding constant, surface pressure, surface excess, surface area covered per CHCC metallosurfactant molecule, free energy minimum, standard free energies of micellization and adsorption, standard enthalpy and entropy of micellization, and Gibb's free energy of transfer have been calculated. The hydrodynamic diameters and zeta potentials of the CHCC metallomicelles have been measured by dynamic light scattering method. Transmission electron microscopy was employed to confirm the presence of worm‐like micelles.

Solubilization of Nile Red in Micelles and Protomicelles of Sodium Dodecyl Sulfate.

A spectrophotometric study of the solubilization and aggregation of the Nile red dye (NR) in premicellar and micellar aqueous solutions of sodium dodecyl sulfate (SDS) was carried out. The experiments were conducted both with saturated solutions of NR under conditions of thermodynamic equilibrium of the solution with a dye precipitate, and at a constant concentration of NR in a homogeneous solution. In the first case, it was proved theoretically and verified experimentally that with an increase in the SDS concentration, the NR concentration always increases, and at the limit of low concentrations, the dependence is linear. In both cases, the concentration of NR dimers as a function passes through a maximum in the premicellar region. There are no dimers in the micellar region. The extinction coefficients of NR monomers in SDS solutions were determined both below and above the critical micelle concentration (CMC) of SDS. A solubilization curve with branches for the premicellar and micellar regions was constructed, the intersection of which was used to find the CMC value in the system under study. The state of deep supersaturation of the NR solution in the metastable state upon dilution of the micellar system with water was studied. It was found that, in addition to dimers, molecular aggregates of higher orders were also formed.

Physico-chemical parameters for the assembly of moxifloxacin hydrochloride and cetyltrimethylammonium chloride mixture in aqueous and alcoholic media

The aggregation behavior of the mixture of cetyltrimethylammonium chloride (CTAC), a cationic surfactant, and moxifloxacin hydrochloride (MFH), a fourth-generation fluoroquinolone antibiotic drug, has been studied using the conductivity technique in aqueous and alcoholic (EtOH, 1-PrOH, and 2-BuOH) media. The study was performed at several temperatures between 298.15 and 323.15 K at 5 K intervals. The assembly has been characterized by evaluating the micellar parameters, such as the critical micelle concentration (CMC) and the counter ion binding (β), of the CTAC + MFH mixture. The values of the CMC for the assembly of the CTAC + MFH mixture were reliant on the composition of alcohols in the mixed solvents and the temperature. The CMC values of the CTAC + MFH mixture increased with increasing temperature; that is, assembly was delayed by increased temperature. The micellization of the CTAC + MFH mixed system was delayed in alcoholic media. The observed -ΔGm0 values for the association of the CTAC + MFH mixed system demonstrated a spontaneous aggregation process under all study conditions. Based on the -ΔHm0 and +ΔSm0 values, the association of the CTAC + MFH mixture is exothermic and the interaction forces acting between the CTAC and MFH species are hydrophobic, ion–dipole, and electrostatic interactions. The transfer properties and enthalpy–entropy compensation were also assessed and described comprehensively.

Conductometric and Fluorescence Probe Analysis to Investigate the Interaction between Bioactive Peptide and Bile Salts: A Micellar State Study.

The present work deals with the micellar state study of sodium cholate and sodium deoxycholate in the aqueous solution of a bioactive peptide, namely glycyl dipeptide, having different concentrations through conductivity and fluorescence methods at different temperatures. The data obtained from conductivity is plotted against the concentration of Bile salts, and CMC (critical micelle concentration) values are calculated. The results realized have been elucidated with reference to Glycyl dipeptide-bile salts hydrophobic/hydrophilic interactions existing in solution. In addition, the CMC values converted to mole fraction (Xcmc) values have been used to evaluate the standard thermodynamic factors of micellization viz., enthalpy H, free energy ΔGm0, and entropy (ΔSm0) which extract information regarding thermodynamic feasibility of micellar state, energy alteration, and the assorted interactions established in the existing (bile salts-water-glycyl dipeptide) system. Furthermore, the pyrene fluorescence spectrum has also been utilized to study the change in micro polarity induced by the interactions of bile salts with glycyl dipeptide and the aggregation action of bile salts. The decrease in modification in the ratio of intensities of first and third peaks i.e., (I1/I3) for the pyrene molecules in aqueous bile salts solution by the addition of dipeptide, demonstrates that the micelle polarity is affected by glycyl dipeptide. This ratio has also been utilized to determine CMC values for the studied system, and the results have been found to be in good correlation with observations made in conductivity studies.

Nanoarchitectonics-based model membrane platforms for probing membrane-disruptive interactions of odd-chain antimicrobial lipids

The use of nanoscience tools to investigate how antimicrobial lipids disrupt phospholipid membranes has greatly advanced molecular-level biophysical understanding and opened the door to new application possibilities. Until now, relevant studies have focused on even-chain antimicrobial lipids while there remains an outstanding need to investigate the membrane-disruptive properties of odd-chain antimicrobial lipids that are known to be highly biologically active. Herein, using the quartz crystal microbalance-dissipation (QCM-D) and electrochemical impedance spectroscopy (EIS) techniques, we investigated how an 11-carbon, saturated fatty acid and its corresponding monoglyceride—termed undecanoic acid and monoundecanoin, respectively—disrupt membrane-mimicking phospholipid bilayers with different nanoarchitectures. QCM-D tracking revealed that undecanoic acid and monoundecanoin caused membrane tubulation and budding from supported lipid bilayers, respectively, and were only active above their experimentally determined critical micelle concentration (CMC) values. Monoundecanoin was more potent due to a lower CMC and electrochemical impedance spectroscopy (EIS) characterization demonstrated that monoundecanoin caused irreversible membrane disruption of a tethered lipid bilayer platform at sufficiently high compound concentrations, whereas undecanoic acid only induced transient membrane disruption. This integrated biophysical approach also led us to identify that the tested 11-carbon antimicrobial lipids cause more extensive membrane disruption than their respective 12-carbon analogues at 2 × CMC, which suggests that they could be promising molecular components within next-generation antimicrobial nanomedicine strategies.

Bioinorganic interest on Co(II) and Zn(II) complexes of pyrrole-based surfactant ligand: Synthesis, characterization, and in silico-ADME study

This study aimed to design and develop surfactant-incorporated drugs to address the issues related to their antibacterial properties and drug delivery systems. Herein, a Schiff base ligand (HL), (E)-N-((1H-pyrrol-3yl)methylene)dodecan-1-amine, and its two metal complexes [[Co(HL)2.2H2O] Cl2.H2O]] (1) and [[Zn(HL)2.Cl] Cl.3H2O]] (2) was synthesized from the seed compounds laurylamine (LA) and pyrrole-3-carboxaldehyde (P3C) by a wet chemical method. They were fully characterized by elemental microanalysis, FT-IR, 1H, 13C NMR, ESI-MS, MALDI-TOF-MS, and UV-visible spectroscopy. Characterization was further accomplished by magnetic moment measurements, powder X-ray diffraction (PXRD), and thermo gravimetric (TGA/DTA) analyses. Based on the executed data, an octahedral geometry was proposed for complex 1 and distorted trigonal bipyramidal geometry for complex 2. This was further authenticated by running the MM2 function in the CsChemOffice Ultra 16 programs to achieve minimum energy. The electrolytic nature of the prepared compounds was evaluated using conductivity measurements. The critical micelle concentration (CMC) values of the complexes were obtained from a graphical plot of concentration versus specific conductivity. The Kirby-Bauer paper disk diffusion technique was used to explore the antibacterial activity of the synthesized compounds. Moreover, the metal complexes exhibited remarkable antibacterial activities. These were further quantified using minimum inhibitory concentration (MIC) tests. An in silico ADME study was conducted to predict the drug-likeliness properties of all synthesized compounds.

Meso- and Macroporous Polymer Gels for Efficient Adsorption of Block Copolymer Surfactants.

An understanding of surfactant adsorption at solid-liquid interfaces is important for solving many technological problems. This work evaluates surfactant adsorption abilities of high surface area (200-600 m2/g), high porosity (>90%), hierarchically structured open pore polymer gels. Specifically, the interactions of a nonionic block copolymer surfactant, poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO), with three polymer gels, namely, syndiotactic polystyrene (sPS), polyimide (PI), and polyurea (PUA) offering different surface energy values, are evaluated at surfactant concentrations below and well above the critical micelle concentration (CMC). Two distinct surfactant adsorption behaviors are identified from the surface tension and nuclear magnetic resonance data. At concentrations below CMC, the surfactant molecules adsorb as a monolayer on polymer strands, inferred from the Langmuir-type adsorption isotherm, with the adsorbed amount increasing with the specific surface area of the polymer gel. The study reports for the first time that the gels show a strong surfactant adsorption above CMC, with the effective surfactant concentration in the gel reaching several folds of the CMC values. The effective surfactant concentration in the gel is analyzed using surfactant micelle size, polymer surface energy, and pore size of the gel. The findings of this study may have strong implications in liquid-liquid separation problems and in the removal of small dye molecules, heavy metal ions, and living organisms from aqueous streams.

A comparative study on photophysics of meso-substituted mono- and bis-BODIPY carbazoles

A comparative study of the photophysics of mono- and bis-BODIPY (BDP) substituted N-butylcarbazoles (CBZ): CBZ-BDP and CBZ-bisBDP has been carried out. The longest wavelength electronic absorption band at ∼495 nm corresponds to BODIPY moiety and does not exhibit solvatochromism. The absorbance value of CBZ-bisBDP is twice that of CBZ-BDP due to the presence of two BODIPY chromophores in the former. For both the molecules, fluorescence spectra show locally excited (LE) emission in non-polar solvents and red-shifted broad Intramolecular Charge Transfer (ICT) emission in polar solvents. CBZ-BDP shows a larger red-shift and more significant intensity reduction of the ICT band than the bis-conjugated molecule. Theoretical calculations reveal that the Highest Occupied Molecular Orbitals (HOMO) of the two molecules are localized primarily on the carbazole unit. In contrast, the Lowest Unoccupied Molecular Orbitals (LUMO) are mainly concentrated on BODIPY unit. This suggests that excited state charge transfer in both the fluorophores is from the carbazole unit to the BODIPY unit. The S1 states of both CBZ-BDP and CBZ-bisBDP are Twisted Intramolecular Charge Transfer (TICT) states. The temperature-dependent study in ethyl acetate has shown an increase in emission intensity with temperature accompanied by a blue shift of emission spectrum in CBZ-BDP. In contrast, CBZ-bisBDP displayed a decrease in intensity along with blue shift. Besides, CBZ-bisBDP showed an additional LE emission whose emission intensity gets enhanced with increasing temperature. The Critical Micelle Concentration (CMC) of sodium deoxycholate (NaDC) bile salt in aqueous medium was determined by using CBZ-BDP as a fluorescent probe. Three independent parameters: absorbance, fluorescence intensity and anisotropy of the molecule were employed to determine the CMC value. Cell imaging studies using confocal fluorescence microscopy showed that, unlike the mono-BODIPY, CBZ-bisBDP could penetrate the cells and reveal the cytoplasmic distribution in Hela cells. The IC50 values obtained via MTT assay indicate that the cytotoxicity against cancer cells is significant in CBZ-bisBDP compared to the mono-BODIPY.

Amphiphilic Diblock Copolymers Bearing Poly(Ethylene Glycol) Block: Hydrodynamic Properties in Organic Solvents and Water Micellar Dispersions, Effect of Hydrophobic Block Chemistry on Dispersion Stability and Cytotoxicity.

Despite the fact that amphiphilic block copolymers have been studied in detail by various methods both in common solvents and aqueous dispersions, their hydrodynamic description is still incomplete. In this paper, we present a detailed hydrodynamic study of six commercial diblock copolymers featuring the same hydrophilic block (poly(ethylene glycol), PEG; degree of polymerization is ca. 110 ± 25) and the following hydrophobic blocks: polystyrene, PS35-b-PEG115; poly(methyl methacrylate), PMMA55-b-PEG95; poly(1,4-butadyene), PBd90-b-PEG130; polyethylene PE40-b-PEG85; poly(dimethylsiloxane), PDMS15-b-PEG115; and poly(ɛ-caprolactone), PCL45-b-PEG115. The hydrodynamic properties of block copolymers are investigated in both an organic solvent (tetrahydrofuran) and in water micellar dispersions by the combination of static/dynamic light scattering, viscometry, and analytical ultracentrifugation. All the micellar dispersions demonstrate bimodal particle distributions: small compact (hydrodynamic redii, Rh ≤ 17 nm) spherical particles ascribed to “conventional” core–shell polymer micelles and larger particles ascribed to micellar clusters. Hydrodynamic invariants are (2.4 ± 0.4) × 10−10 g cm2 s−2 K−1 mol−1/3 for all types of micelles used in the study. For aqueous micellar dispersions, in view of their potential biomedical applications, their critical micelle concentration values and cytotoxicities are also reported. The investigated micelles are stable towards precipitation, possess low critical micelle concentration values (with the exception of PDMS15-b-PEG115), and demonstrate low toxicity towards Chinese Hamster Ovarian (CHO-K1) cells.

Hyaluronic acid and cholecalciferol conjugate based nanomicelles: Synthesis, characterization, and cytotoxicity against MCF-7 breast cancer cells

Recently, growing and conclusive evidences showed the particularly close ties between the vitamin D (VD) and breast cancer (BC). However, few researches were focused on the delivery system against breast cancer which based on cholecalciferol (VD3). Herein, we designed a series of self-assembled micelles. The conjugate (HA-VD) of VD3 with hyaluronic acid (HA) actively targeting breast cancer can efficiently delivery doxorubicin (DOX). The HA-VD conjugate was successfully synthesized, which was confirmed using 1H nuclear magnetic resonance (NMR) and Fourier transform infrared (FITR). Preliminary studies of its physical and chemical properties indicated that VD3 was successfully grafted with the HA (HAVD). When the molar ratio was 1:2 and the degree of substitution (DS) was 18.6%, the minimum critical micelle concentration (CMC) value was 0.0137 mg/mL. For DOX-loaded HAVD micelles (DOX/HAVD), the drug loading (DL) was 6.2% and drug encapsulation efficiency (EE) was 79.5%. The DOX/HAVD micelles remain stable in serum for 48 h. The in vitro release rate of DOX decreased after encapsulating compared with that without HAVD encapsulation. The decrease with IC50 of DOX/HAVD micelle was significantly stronger than that of free DOX (p < 0.05) and blank micelles (p < 0.01). At 50% cell inhibition rate, VD3 and DOX acted synergistically on BC cells. Hence, the HAVD micelles can significantly improve the therapeutic effect of DOX against BC cells. In a word, the DOX/HAVD micelles have great potential in treating breast cancer.

Self-assembly, surface, antibacterial, and solubilization properties of phenylglycine type amino acid-based cationic surfactants

Here, synthesis and characterization of amino acid-based chiral cationic surfactants containing phenylglycine moiety, l-phenylglycine hydrochloride octyl ester (L-PgC8E), and l-phenylglycine hydrochloride decyl ester (L-PgC10E), and their physicochemical properties such as the micellization, surface, and volumetric parameters have been reported. In addition, the structural analyses of the aggregates of these esters were also performed by dynamic light scattering (DLS) and transmission electron microscopy (TEM) techniques. It was found that the presence of a phenyl ring in the head group promoted the micelle formation leading to a smaller critical micelle concentration (CMC) value and enhancing the adsorption efficiency with an increased hydrocarbon chain. Besides, the antibacterial activities of the synthesized surfactants have been explored against three Gram-positive (G+) and seven Gram-negative (G-) bacteria below and above their CMC values by measuring the zone of inhibition diameter. The results showed that L-PgC8E was more active than L-PgC10E against all bacteria; this was explained by the formation of smaller and less stable aggregates that could interact efficiently with the bacterial membrane. Furthermore, the solubilization power (SP) of both surfactants for Methyl Red (MR) was determined, and it was found that L-PgC10E with a longer hydrocarbon chain and forming a large hydrophobic area by its large aggregates showed a more efficient solubilizing power.

Micellization properties of quinolinium based surfactants: 1-alkylquinolinium bromide and 6-hydroxy-1-alkylquinolinium-bromide by fluorimetry, conductivity and surface tension measurements and its parameters

Quinolinium surfactants possessing pyridinium rings have a wide range of biological applications due to its antimicrobial activity. In this study, we have used quinolinium based surfactant series i.e.1-alkylquinolinium bromide and 6-hydroxy-1-alkylquinolinium-bromide. The physicochemical behavior of quinolinium based surfactant have been carried out by various techniques viz. conductivity, surface tension and fluorescence measurements in aqueous and 10% (v/v) methanol at 300K.The critical micelle concentration (CMC) values found from conductivity, surface tension and fluorescence are in good agreement of a surfactant in aqueous and 10% (v/v) methanol. The CMC value of 1-alkyquinolinium-bromide series is higher than its derivative series (6-hydroxy-1-alkyquinolinium-bromide). The values of Гmax increases with increases chain length of the both the quinolinium surfactants, as well as Amin values increases with increasing chain length of surfactants.

SYNTHESIS AND CHARACTERISTIC OF NANOSILICA FROM GEOTHERMAL SLUDGE: EFFECT OF SURFACTANT

In the synthesis of nanoparticles, the phenomenon of agglomeration is an undesirable condition because the particles formed can be larger. The use of surfactants can prevent the occurrence of this phenomenon. In this study, the use of surfactants was studied in the synthesis of nanosilica from geothermal sludge. The method applied in the synthesis of nanosilica is the sol-gel method. A 1 M sodium hydroxide (NaOH) solution was used to prepare the sol phase, while the gel phase was prepared at pH 5 using a 1.5 M hydrochloric acid (HCl) solution. The surfactants used were alkyl benzene sulfonate (ABS), cetyltrimethylammonium bromide (CTAB), sodium dodecyl sulfate (SDS), and polyvinylpyrrolidone (PVP). The surfactant added to the precursor solution was at the critical micelle concentration (CMC), where the CMC values for each surfactant were 0.15, 0.05, 0.50, and 1.00 wt% for ABS, CTAB, SDS, and PVP, respectively. The experimental results showed that the synthesis of nanosilica without surfactant could produce the product with a purity of 98.03%. Even though the purity is already high, the resulting product experiences agglomeration and surfactants were needed to minimize the occurrence of agglomeration in the product. The surfactant that gives the best product quality is PVP, where the particle size is in the range of 2.01–3.65 nm. However, the product produced with this PVP has a low purity, 56.67%. It is because the sodium chloride (NaCl) is trapped in the surfactant template.

Thermosensitive vancomycin@PLGA-PEG-PLGA/HA hydrogel as an all-in-one treatment for osteomyelitis

Osteomyelitis is a difficult-to-treat infectious disease. Treatment, which includes controlling the infection and removing necrotic tissues, is challenging. Considering the side effects and drug resistance of systemic antibiotics, local drug delivery systems are being explored. Antibiotic-loaded bone cement is the main treatment strategy; however, it has several disadvantages. Thus, based on its thermosensitive gelation properties, poly(D, L-lactide-co-glycolide)–poly(ethylene glycol)–poly(D, L-lactide-co-glycolide) (PLGA-PEG-PLGA) copolymer was used as a sustained-release drug carrier by calibrating its synthesis parameters. We prepared and characterized vancomycin@PLGA-PEG-PLGA/hydroxyapatite (HA) thermosensitive hydrogel with an LA/GA ratio of 15:1. The rheological characteristics, sol–gel phase-transition properties, and critical micelle concentration value of the PLGA-PEG-PLGA/HA complex confirmed that it undergoes a temperature-sensitive sol–gel phase transition. Furthermore, the HA in the composite increased the storage modulus of the system. FT-IR, XRD, and TEM findings showed that HA could be dispersed uniformly in the PLGA-PEG-PLGA polymer. Moreover, HA neutralized acidity during polymer degradation, improving in vitro cytocompatibility. In vitro and in vivo antibacterial experiments showed that the composite sustained-release system exhibited good bone repair characteristics owing to its efficacy in infection treatment. Therefore, vancomycin@PLGA-PEG-PLGA/HA allows sustained release of antibiotics and promotes bone tissue repair, showing potential for wide clinical applicability.

Novel Docetaxel-Loaded Micelles Based on all-trans-Retinoic Acid: Preparation and Pharmacokinetic Study in Rats

AbstractDocetaxel (DTX) is a poorly soluble drug. The purpose of this study was to explore a DTX-loaded micelle delivery system using N-(all-trans-retinoyl)-L-cysteic acid methyl ester sodium salt (XMeNa) as the carrier materials. In this study, amphiphilic surfactant XMeNa was synthesized. Then, the blood biocompatibility and the value of critical micelle concentration (CMC) were assessed by a hemolysis test and pyrene-based fluorescent probe techniques, respectively. The XM-DTX micelles were prepared using the method of thin-film hydration, and characterized by dynamic light scattering and transmission electron microscopy (TEM). The entrapment efficiency (EE) and drug loading efficiency (DLE) were assessed by the ultrafiltration method. In vitro release and pharmacokinetic behaviors of XM-DTX micelles were performed in rats using Taxotere (a commercialized DTX injection) as a control. Our data confirmed the excellent blood biocompatibility of XMeNa as a carrier. XMeNa can self-assemble into micelles in aqueous media with a very low CMC (6.2 μg/mL). The average size and zeta potential of the XM-DTX micelles were 17.3 ± 0.2 nm, and −41.6 ± 0.3 mV, respectively. EE and DLE reached up to 95.3 ± 0.7% and 22.4 ± 0.2%, respectively, which may account for the high solubility of DTX in normal saline. The micelles were spherical in TEM with good dispersion and no aggregation and adhesion, and exhibited good stability after reconstitution over 8 hours. Results from in vitro release assay suggested a much slower release behavior of XM-DTX micelles in comparison to Taxotere. Additionally, XM-DTX micelles prolonged DTX retention in blood circulation, increased the area under the curve by 2.4-fold, and significantly decreased the clearance of the drug. Given above, the XM-DTX micelles could improve the solubility and the release of DTX. The amphiphilic surfactant XMeNa also exhibited great potential as a vehicle for exploring delivery of poorly water soluble drugs in the future.

Synthesis of Cationic Surfactant N, N-(2-Laurate-Ethyl) Stearamidium Chloride

The cationic surfactant of N, N-(2-Lauric-Ethyl) Stearamidium Chloride had been successfully synthesized. It is long-chain alkyl surfactant derivative from ammonium salt with amide. Cationic surfactants that are synthesized from fatty acid derivatives are stearic acid and lauric acid. Stearic acid is used as stearamide-making material which is the product of methyl stearate amidation with diethanolamine use methoxide sodium catalyst. Lauric acid was used as esterification material with stearamide thus obtaining N, N-(2-Lauric-Ethyl) Stearamide of alcanolamide ester. Alcanolamide ester continued by salting reaction use HCl gas until obtained cationic surfactant of N, N-(2-Lauric-Ethyl) Stearimidium Chloride. Each compound analyzed function groups by FT-IR spectrophotometric with the analyzed change of melting points, and a part compound analyzed surface tension characteristic with measuring Critical Micelle Concentration (CMC) with use Du Nouy ring method. The analysis product obtained shows that methyl stearate by yield in the amount of 91.66% shows that melting point of 40.5°C, stearamide with yield in the amount of 87.6% show that melting point as 185°C by CMC value 0.133 mol/ L in 40.7 dyne/cm surface tension. Alcanolamide ester with a yield in the amount of 84.7% has a melting point of 55°C by a CMC value of 0.067 mol/L in 36.1 dyne/cm surface tension, and cationic surfactant has a melting point of 45°C by CMC value 0.055 mol/L in 31,1 dyne/cm surface tension. stearamide with a yield in the amount of 87.6% show that melting point of 185°C by a CMC value of 0.133 mol/L in 40.7 dyne/cm surface tension. Alcanolamide ester with a yield in the amount of 84.7% has a melting point of 55°C by a CMC value of 0.067 mol/L in 36.1 dyne/cm surface tension, and cationic surfactant has melting point as 45°C by CMC value 0.055 mol/L in 31,1 dyne/cm surface tension. stearamide with a yield in the amount of 87.6% show that melting point of 185°C by a CMC value of 0.133 mol/L in 40.7 dyne/cm surface tension. Alcanolamide ester with a yield in the amount of 84.7% has a melting point of 55°C by a CMC value of 0.067 mol/L in 36.1 dyne/cm surface tension, and cationic surfactant has a melting point of 45°C by CMC value 0.055 mol/L in 31,1 dyne/cm surface tension.

Modulating aggregation behaviour and surface properties of cationic & anionic surfactant with surface active ionic liquid 1-decyl-3-methylimidazolium chloride [C10mim][Cl]: Role of surfactant head group

Aggregation behaviour of two conventional surfactants dodecyl trimethylammonium chloride (DTAC) and sodium dodecyl sulphate (SDS) in aqueous medium, in the absence and presence of different wt% (0.02,0.05,0.10) of ionic liquid (IL), 1-decyl-3-methylimidazolium chloride [C10mim][Cl] and at various temperatures (298.15,303.15,308.15) K has been studied. The critical micelle concentration (CMC) of IL-added aqueous surfactant solutions were obtained by state of art techniques i.e., conductivity, UV–Vis, fluorescence spectroscopy and surface tension. Further, the CMC value have been utilised to obtain various thermodynamic parameters and interfacial properties by conductivity and surface tension method. The recovered parameters were used to understand the effect of IL on aqueous SDS/DTAC solutions. The structural changes that occurred in the mixed system (surfactants + IL [C10mim][Cl]) were also explored by fourier transform infrared spectroscopy.

Functionalized PEG-PLA nanoparticles for brain targeted delivery of ketoconazole contribute to pregnane X receptor overexpressing in drug-resistant epilepsy

ObjectiveTo develop a functionalized PEG-PLA nanoparticle system containing ketoconazole (KCZ) to overcome the overactivity of pregnane X receptor (PXR) for the treatment of drug-resistant epilepsy (DRE). SignificanceKCZ was developed as a therapy strategy for DRE limited by its lethal hepatotoxicity and minute brain concentration. KCZ-incorporated nanoparticles modified with angiopep-2 (NPs/KCZ) could reduce adverse effects of KCZ and achieve epileptic foci-targeted drug delivery. MethodsNPs/KCZ was prepared by thin-film hydration method and characterized in vitro and in vivo. The efficacy evaluation of NPs/KCZ was evaluated in a kainic acid (KA)-induced mice model of epilepsy with carbamazepine (CBZ) treatment. ResultsThe mean particle size and Zeta potential of NPs/KCZ were 17.84 ± 0.33 nm and − 2.28 ± 0.12 mV, respectively. The drug-loading (DL%) of KCZ in nanoparticles was 8.96 ± 0.12 % and the entrapment efficiency (EE%) was 98.56 ± 0.02 %. The critical value of critical micelle concentration was 10−3.3 mg/ml. No obvious cytotoxicity was found in vitro. The behavioral and electrographic seizure activities were obviously attenuated in NPs/KCZ+CBZ group. The CBZ concentration of brain tissues in mice treated with NPs/KCZ+CBZ was significantly increased than those treated with CBZ alone (P = 0.0028). A significantly decreased expression level of PXR and its downstream proteins was observed in NPs/KCZ+CBZ group compared with that in the control and CBZ group (All P < 0.05). ConclusionOur results showed that NPs/KCZ achieved the epileptic foci-targeted delivery of KCZ and ameliorated the efficacy of CBZ on DRE by attenuating the overactivity of PXR.

The physicochemical variables and interaction forces for the association of dodecyltrimethylammonium bromide + cefixime trihydrate mixture in aq. short chain alcohols and urea media at different temperatures

To develop the drug formulation and reduce antibiotic resistance in the human body, it is essential to study the drug-surfactant interaction. Herein, the interactions between cefixime trihydrate (CMT) and dodecyltrimethylammonium bromide (DTAB) have been evaluated in different experimental situations at a certain range of temperature (300.55–320.55 K) by means of conductivity measurement. The micellar parameters (CMC, degree of counter ion binding (β)) along with some thermodynamic variables like ΔGm0, ΔHm0, and ΔSm0 etc. were evaluated to investigate the interactions between CMT and DTAB. The plot of specific conductivity against surfactant concentration of the DTAB + CMT mixed system was used to determine critical micelle concentration (CMC). The increase of concentration of alcohols (ethanol and 1-propanol) and urea lowers the counterion binding and enhance the CMC values of the DTAB + CMT system. The increase in temperature causes delayed micellization of DTAB + CMT mixture both in aq. alcoholic and urea media. The alteration of CMC values of the DTAB + CMT implies the existence of interaction between DTAB and CMT in the study environment. The micellization of the DTAB + CMT mixed system in all experimental conditions investigated is spontaneous process that has been confirmed by the achieved negative values of ΔGm0. The values of ΔHm0 and ΔSm0 expose the presence of hydrophobic and electrostatic interactions between CMT and DTAB while the contribution of electrostatic interaction is the main force in aq. EtOH medium.

Effect of rhamnolipids on the biodegradation of m-dichlorobenzene in biotrickling filters: Performance and mechanism

In this study, the effect of rhamnolipids (RL) on m-dichlorobenzene (m-DCB) removal and biofilm was investigated in two biotrickling filters (BTF) (BTF1: blank control; BTF2: RL addition). The critical micelle concentration (CMC) value of RL was 75.6 mg L−1, and the RL could significantly improve the solubilization of m-DCB. The results showed that the optimal concentration of RL was 180 mg L−1. The removal efficiency (RE) of m-DCB dropped by 42.4% for BTF1 no fed with RL and only 28.2% for BTF2 fed with RL when the inlet concentration increased from 200 to 1400 mg m−3 at an empty bed time (EBRT) of 60 s. RL increased the secretion of extracellular polymers (EPS) and the ratio of Protein/Polysaccharide, which improved the mass transfer of m-DCB to the biofilm. RL also had a facilitating effect on catechol-1,2-dioxygenase (C12O) enzyme activity. Furthermore, RL increased Zeta potential and facilitated microorganisms to form biofilm. The dominant microorganisms of microbial community were increased and the application of RL promoted the enrichment of them.