Critical micellar concentration

Man-made gas hydrates create serious problems for the oil and gas production industry. Prevention of hydrate formation requires significant costs. In addition, it is important to understand the physics and parameters of hydrate formation processes. Therefore, an urgent task is to establish the peculiarities of the kinetics and parameters of hydrate formation in technological processes. The object of the research was the parameters of the beginning of mass crystallization of gas hydrates in reservoir systems. The process of hydrate formation at the phase boundary is manifested by the formation of a thin layer of hydrate in the form of a film. In the course of experimental studies, it was established that this process is visually fixed by clouding of the pre-specular phase boundary. The effect of distortion of the interphase boundary is explained by the formation, growth, and chaotic accumulation of gas hydrate microcrystals at this boundary. Based on the results of theoretical and experimental studies, the methodology of operative laboratory

A novel multi-test tube rocking cell unit has been used to generate large amounts of data to investigate the relationship between gas hydrate formation induction time and subcooling. The experiments included tests to determine the induction time for a natural gas and water system at a wide range of pressures and subcooling. Over 500 induction times were measured at pressure ranging from 2 to 17 MPa. The statistical analysis of the results shows that the commencement of hydrate growth is logarithmically related to subcooling, and that the scatter of the onset of hydrate growth is greater at higher subcooling. It was also shown that the induction time for hydrate growth was lower at higher pressures at similar levels of subcooling.

surfactant molecules. Though much attention has been paid Spectral change of a cationic dye 3,3-diethylthiacyanine iodide to the study of the dye-surfactant interaction at and around (THIA) in the presence of an anionic surfactant AOT has been the critical micellar concentrations (CMC) of the surfacpresented. The THIA-AOT system exhibits blue-shifted metachtants, there are also interesting reports (4, 10-13) on the romasia at AOT concentrations below its critical micellar concendye-surfactant interaction below the CMC of surfactants. Anyway, the progressive spectral change of a dye-surfactant electrostatically bound dye-AOT complex (DS). Metachromasia system at varying surfactant concentrations indicates that is gradually reversed to the monomeric band (peak at 425 nm) by none of the observed spectra can be assigned to a definite AOT above its CMC. Principal component analysis (PCA) composition of the dye-surfactant complex, and more than method has been applied for spectral analysis; the results show that the metachromatic peaks at 377 and 366 nm originate, re-one species of the complexes may have contributed to the spectively, from trimer and hexamer of the dye associated with observed spectra even at a particular dye to surfactant ratio. AOT. From PCA, the molar absorption coefficient spectra of the There are reports on the determination of the compositions individual absorbing components and the equilibrium constants and molar absorption coefficients of dye-polyanion comfor the systems, monomer `trimer and hexamer `monomer plexes (18-21), but similar reports on the dye-surfactant below and above CMC of AOT, respectively, have also been obsystems are scanty . In this paper we report the spectained. The micellar aggregation number of AOT obtained from trophotometric results and the application of the extended PCA is found to be 16 which is in good agreement with the literaprincipal component analysis (PCA) method ( ) for the ture value.

In this work, the critical micellar concentration (CMC) for three anionic and nonionic surfactants was measured. The commercial products employed were Texapon 5 (sodium lauryl ether sulfate), Surfacpol 906 (ethoxylated nonylphenol), and Canarcel TW80 (ethoxylated sorbitan monooleate), and the CMC measured values were 0.941, 0.0934, and 0.05 mM, respectively. The diesel adsorption on sandy and clayey soils was characterized by means of the partition coefficients K d , resulting in values of 0.5 and 1.4 mL/g for sandy and clayey soil, respectively. There are a few reports of K d values for complex mixtures of organic compounds such as diesel. Retardation factors for every system were calculated, resulting in 2.6 and 2.9 for the sandy and the clayey soil, respectively. Interestingly, the retardation factors for both soils are quite similar, even when the diesel-soil partition coefficient for clayey soil is threefold the value for the sandy soil. Finally, diesel-removal efficiencies for the three surfactants from an aged contaminated sandy soil were evaluated at the sub-CMC and supra-CMC levels, at concentrations of 0.5, 5, 100 and 300 times the CMC for every surfactant. The results of the soil's washing as a removal percentage were 46.4 -74.2, 41.9 -83.3, and 52.5 -88.2% for Texapon 5, Canarcel TW80, and Surfacpol 906, respectively. Experimental data were recalculated according to an equation where f oc /K d is a function of the total surfactant dose [D]. The experimental behavior for concentrations between 0.47 and 47 mM for Texapon, 0.025 and 2.5 mM for Canarcel, and 0.046 and 4.66 mM for Surfacpol was predicted by the mentioned equation. After these values, the f oc /K d values increased at a very accelerated rate, especially for the case of Surfacpol.

The low molecular weight gelators (LMWGs) are small organic molecules known for their gel forming abilities. Depending on experimental conditions, these molecules self-assemble and immobilize organic solvents or water to form organogels or hydrogels, respectively. They find applications in a variety of fields including material science, environmental science and drug delivery. This paper reports a serendipitous observation of the gelation of polylactide (PLA) derivative in a nonpolar solvent to form a new nano-organogel. The structural characteristics of the gel were evaluated. The results show nanometer-sized hexagonal particles, average molecular weight of <1000, presence of double bonds and carboxylic acid functional groups, and nonionic amphiphilic-like structure, which are inherent features that would make the nanostructure a potential versatile drug carrier. Additionally, the abundance of lactyl (CH3CHCO.O) repeating units in its chain length that are contributory to its hy...

The glycerol-3-phosphate (G3P) transporter, GlpT, from Escherichia coli mediates G3P and inorganic phosphate exchange across the bacterial inner membrane. It possesses 12 transmembrane R-helices and is a member of the Major Facilitator Superfamily. Here we report overexpression, purification, and characterization of GlpT. Extensive optimization applied to the DNA construct and cell culture has led to a protocol yielding ∼1.8 mg of the transporter protein per liter of E. coli culture. After purification, this protein binds substrates in detergent solution, as measured by tryptophan fluorescence quenching, and its dissociation constants for G3P, glycerol-2-phosphate, and inorganic phosphate at neutral pH are 3.64, 0.34, and 9.18 µM, respectively. It also shows transport activity upon reconstitution into proteoliposomes. The phosphate efflux rate of the transporter in the presence of G3P is measured to be 29 µmol min -1 mg -1 at pH 7.0 and 37 °C, corresponding to 24 mol of phosphate s -1 (mol of protein) -1 . In addition, the glycerol-3-phosphate transporter is monomeric and stable over a wide pH range and in the presence of a variety of detergents. This preparation of GlpT provides ideal material for biochemical, biophysical, and structural studies of the glycerol-3-phosphate transporter.

Macrophages as phagocytic cells play an important role in our body's defence. In response to diverse stimuli, macrophages can polarise into several phenotypes with a different activity that affects the development of various diseases including cancer or chronic inflammation. Corticosteroids are among the stimuli that induce changes in polarisation from the proinflammatory phenotype of macrophages to the anti-inflammatory one. Although corticosteroids are potent anti-inflammatory substances, they cause serious side effects during therapy. Therefore, we prepared macrophages-specific poly(lactic-co-glycolic acid) (PLGA) nanospheres with incorporated dexamethasone (DEX) that can be therapeutically used in various indications with reduced harmful effects. Several types of PLGA, varying either in the ratio of lactic and glycolic acid or in the structure, were used for nanosphere formulation. The preparation was performed by two methods: nanoprecipitation and emulsification solvent evaporation. We obtained nanoparticles with a size range of 150-290 nm, which corresponds to the preferred size range for macrophage uptake. Nanospheres with zeta potential ranging from -10 to -15 mV were sufficiently monodisperse with a polydispersity index under 0.2. The loading efficiency of DEX surpassed 25%. This indicates that DEX-loaded nanospheres are a promising tool for corticosteroid site-specific delivery. For biological evaluation, the human monocyte cell line THP-1 was used. THP-1 monocytes were differentiated into macrophages by phorbol 12-myristate 13-acetate (PMA). Cytotoxicity tests by MTS assay and immunogenicity tests by qRT-PCR were performed to determine the biological response of the cells to our DEX-loaded PLGA nanospheres.

The protein aggregation±dissociation process induced by divalent cations was studied using diluted aqueous dispersions of a native soy isolate. Turbidity, as a protein aggregation indicator, was quanti®ed at a ®xed time after addition of increasing amounts of CaCl 2 , MgCl 2 or an equimolar mixture of them. In all cases turbidity values attained with Ca 2+ were higher than these obtained with Mg 2+ . The eects of phosphate, citrate and chloride presence were also determined. Phosphate, becomes incorporated into Ca 2+ -induced aggregates, but not in Mg 2+ ones. Both citrate and chloride ions inhibit protein aggregation and contribute to the dissociation of previously formed aggregates. Low citrate concentrations allowed aggregate formation, even at high CaCl 2 concentrations; this behavior was not observed in the presence of MgCl 2 . A sedimentation based test was developed as a stability parameter of dispersions of soy protein aggregates. Results showed that even though aggregation was induced by divalent cations, competition between phosphate, citrate and soy protein could modify the aggregates' properties. Optimum aggregation conditions were established from combinations of these variables.

Experiments of turbidity decrease induced by detergents were systematically performed to characterize the solubilization of Phormidium laminosum membrane fragments. SDS, Triton X-100 and a mixture of octyl glucoside/decyl maltoside/lithium dodecyl sulfate (OG/DM/LiDS, in a molar ratio of 4.19:2.54:1) were used. The detergent concentration in the aqueous phase (D w) and the effective detergent/chlorophyll ratio in mixed aggregates (R e) were determined. Both parameters increased during the solubilization and in an exponential way in the range from 10 to 90% solubilization. At detergent concentrations which caused the complete solubilization, D w values were close to the described critical micellar concentrations (cmc), but solubilization started at concentrations well below the cmc. At the onset of solubilization five molecules of SDS, one of Triton X-100 and three of the mixture OG/DM/LiDS, per chlorophyll molecule, saturated the membrane fragments. The increase of D w and R e values was characterized by two constants. This permits the design of a model to predict the detergent concentration which produces a desired solubilization of thylakoid membrane fragments for a given chlorophyll concentration.

Fil: Mainez, Maria Esperanza. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Santa Fe. Instituto de Desarrollo Tecnologico para la Industria Quimica. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnologico para la Industria Quimica; Argentina

T he effec t o f e ig ht o rga ni c co unter-io ns (a li phati c. both mo no and dica rboxy lates) on the s urface and mice ll ar behaviou r o f decy l and dodecy l ammo nium carboxy lates in aqu eous soluti on has been exa min ed by d iffe re nt physicochem ica l tec hn iques suc h as surface te nsio n, dye solubi lza tion, cond uc tance viscosit y a nd nu clea r magnetic reso nance. T he e ffec t of th ese cou nter-io ns as obse rved fro m surface ac ti vit y, a nd c riti ca l mi ce ll e co nce ntrati o n (CMC) is explain ed in term s of th eir conde nsati o n /pe ne trati o n o nto/int o th e m ice ll es. T he dec rease in C MC a nd in crease in cou nte r-io n bind in g of cati o nic surfac ta nts is attri buted to the inc reased hydrophobic ity in alky l c hain of co unte r-io ns. In th e case of mo nocarboxy late co unte r-io ns, CMC dec reases sig nifica ntl y in the ord er: II-butyrate < propi o nate < ace tate <fo rma te. w hile for dicarboxy lates decrease in CMC wi th in crease in nu mbe r o f ca rbon ato ms in the co unter-io n is less substant ial. Compa red to mo nocarboxy lates, di carboxy late counte r-io ns co nd e nse stro ng ly o nto the mi ce ll e su rface a nd thus are capab le of be in g easi ly incorpo rated into the mi celles and co nsequentl y show g rea te r sur face ac ti vity, and lower CMC o f cati o nic surfac tant. The effect o f te mperature o n surface activ ity and mi cell ar behav io ur of dec y l ammo niu m succ in ate is also re po rted.

Conductivities of (0.001–0.012) m sodium dodecyl sulfate have been determined in water and in the presence of 0.10 m aqueous glycine/alanine/glycylglycine at 298.15, 303.15, 308.15, and 313.15 K. From the specific conductivity data, the critical micellar concentration, degree of counter ion association, degree of counterion dissociation, free energy of transfer of hydrophobic chain from the medium to interior of the micelle, and surface contribution, standard free energy of micellization, standard enthalpy of micellization, and standard entropy of micellization of sodium dodecyl sulfate have been computed. The thermodynamic parameters of micellization and the effect of additives on these parameters have been used to study the interactions present in the micellar systems.

Bile acids are a special group of biological surfactants which can express different physiological and pharmacological effects. Micellar solutions of bile acids can solubilizate poorly soluble organic substances and improve their resorbtion. Above their critical micellar concentration (CMC) values, bile acids can cause interruption of membrane's integrity. Resveratrol (trans-3,5,4 -trihydroxystilbene) is a stilbene phytoalexine and studies reported that it can prevent or reduce diseases such as cancer and coronary heart disease. In this study, we examined affinity of different bile acids (CA, 12-MDCA, 12-MCA, 7-MCA, 7,12-DCA, 3,7,12-TCA) micellar solutions for resveratrol solubilization. CMC values for bile acids were determined by conductivity measurements. Concentration of micellar solutions were 0.25, 0.5, 0.75, 1.0, 1.25, 1.5, 1.75, 2.0 CMC value, for each acid respectively. At the same time, we investigated membranolytical potential of each acid. Solubilizated resveratrol was quantified using HPLC system with UV detection. Membranolytical potential was determined from citrate rabbit blood. Structures of mixed micelles of each bile acid and resveratrol were explained, and multiple linear regression equations for solubilization of resveratrol on different concentrations of bile acids were obtained. Micellar solution of 3,7,12-TCA had the biggest affinity for resveratrol solubilization and then, in decreasing order 7-MCA > 7, 12-DCA > 12-MCA > 12-MDCA > CA. Also, 3,7,12-TCA had the lowest membranolytical potential.

Abstract. Critical micelle concentrations (CMC) of
sodium salts of cholic, deoxycholic and chenodeoxycholic
acids in phosphate buffer (pH 7.92) have been
determined from microcalorimetric titration curves.
The obtained values of 18.4_+0.6, 5.3_+0.2 and
7.0 _+ 0.2 mM, respectively, for Na cholate, Na deoxycholate
and Na chenodeoxycholate are close to literature
values obtained by other methods. CMC values
for 'secondary' micelles were also obtained. This microcalorimetric
titration method gives highly reproducible
results and rapid determination of CMC values of
bile acid salts.
Key words: microcalorimetric titration, critical micelle concentration
(CMC), bile acid salts, cholate, deoxycholate, chenodeoxycholate.

The influence of nonionogenic, anionic and cationic surfactants on the magnetic relaxation and luminescence properties of gadolinium(III), terbium(III), and dysprosium(III) complexes with psulfonatothiacalix[4]arene (TCAS) was studied. It was shown that the presence of both neutral and anionic surfactant does not influence the magnetic relaxation properties of GdTCAS as well as on the luminescence intensity of the TbTCAS and DyTCAS complexes. The presence of cationic surfactant at the concentration less than critical micellar concentration led to the formation of associates with stoichiometric composition with the Tb (Dy, Gd) TCAS complexes. These associates are characterized by more intensive luminescence, as compared to the initial TbTCAS and DyTCAS complexes.

The critical micellar concentration (CMC) values of keto derivatives of cholic acid (3␣,12␣-dihydroxy-7-oxo-5␤-cholanoic acid, 3␣,7␣-dihydroxy-12-oxo-5␤-cholanoic acid, 12␣-hydroxy-3,7-dioxo-5␤-cholanoic acid, 3␣-hydroxy-7,12-dioxo-5␤-cholanoic acid, 3,7,12triketo-5␤-cholanoic acid) and cholic acid itself, were determined. Replacement of hydroxyl groups in cholic acid molecule with keto groups yields the derivatives whose CMC values increase with increase in the number of keto groups introduced. The CMCs of derivatives with the same number of keto groups but at different positions do not differ significantly. The relationship between the number of keto groups in the molecule of cholic acid keto derivatives and CMC value can be described by the following equation: CMC = 43 number of keto groups + 14.667. The effect of NaCl concentration on CMC increases with increase in the number of keto groups.

The hemolytic activities of sodium deoxycholate (DChol) and its tauro-conjugate (TDChol) and glyco-conjugate (GDChol) were analysed. 50 % hemolysis occurred in 30 min at pH 7.3, at the concentrations of these detergents equal to 0.044, 0.042 and 0.040 % respectively. These values are below their critical micellar concentrations. Based on its kinetics, this hemolysis is classified as being of permeability type. The detergents increase the permeability of erythrocyte membranes to KCl, and colloid osmotic hemolysis occurs. The minimum of hemolytic activity of the three cholates is at about pH 7.5. A very high increase in hemolytic activity occurs at pHs below 6.8, 6.5 and 6.2 for DChol, TDChol, and GDChol, respectively. These values are close to the pK(a) for DChol (6.2), but much higher than the pK(a) for TDChol (1.9) and GDChol (4.8). It is therefore suggested that the increase in hemolytic activity is not a result of the protonation of the anionic groups of the cholates. At acidific...

One topic of this study is the comparison of different preparation techniques to build up solid supported lipid bilayers onto gold substrates. The deposited lipid bilayers were investigated by a.c. impedance spectroscopy. Three different strategies were applied: (1) The gold surface was initially covered with a chemisorbed monolayer of octadecanethiol or 1,2-dimyristoyl-sn-glycero-3-phosphothioethanol (DMPTE). The second monolayer consisting of phospholipids was then deposited onto this hydrophobic surface by (i) the Langmuir-Schaefer-technique, (ii) from lipid solution in n-decane/isobutanol, (iii) by the lipid/detergent dilution technique or (iv) by fusion of vesicles. (2) Charged molecules carrying thiol-anchors for attachment to the gold surface by chemisorption were used. Negatively charged surfaces of 3-mercaptopropionic acid were found to be excellent substrates that allow the attachment of planar lipid bilayers by applying positively charged dimethyldioctadecylammoniumbromide (DODAB) vesicles or negatively charged 1,2-dipalmitoyl-sn-glycero-3-phosphoglycerol vesicles in the presence of chelating Ca2+-ions. If positively charged first monolayers of mercaptoethylammoniumhydrochloride were used we were able to attach mixed ethanolamine vesicles to form planar lipid bilayers via electrostatic interaction. (3) Direct deposition of lipid bilayers is possible from vesicles containing 1,2-dimyristoyl-sn-glycero-3-phosphothioethanol (DMPTE). A critical amount of more than 50 mol% of DMPTE was found to be necessary to form a solid supported lipid bilayer. Bilayers obtained with these different preparation techniques were scrutinized with respect to their capacitances, kinetics of formation and their long-term stabilities by impedance spectroscopy. The second feature of this paper is the application of the supported bilayers to study ion transport through channel-forming peptides. We used a DODAB-bilayer for the reconstitution of gramicidin D channels. By circular dichroism measurements we verified that the peptide is in its channel conformation. The ion transport of Cs +-ions through the channels was recorded by impedance analysis.

A crossover is observed in the variation of the reduced viscosity, qsp/c, as a function of the concentration, c, for the systems poly(methyl methyacrylate)/nitromethane and poly(vinyl-2 pyridine)/benzene. This crossover is correlated with the critical concentration of the polymer c** in which the macromolecular coils start their contacts. The critical concentration c** is related with the molecular weight and the intrinsic viscosity of the polymer through the scaling laws: c**oc M-= and c**oc [q]-l.

Tuberculosis (TB) is the second most deadly infectious disease behind the Human Immunodeficiency Virus (HIV). An effective pharmacotherapy has been available for more than 5 decades. However, the length of the treatment and the pill burden result in low patient compliance and adherence to the regimens. Nanotechnologies can overcome these basic technological drawbacks. The present work explored the molecular implications governing the encapsulation and water solubilization of RIF within flower-like micelles of poly(epsilon-caprolactone)-b-poly(ethylene glycol)-poly(epsilon-caprolactone) (PCL-PEG-PCL) block copolymers. Ten derivatives of different molecular weight and hydrophobic/hydrophilic caprolactone/ethylene oxide ratio (CL/EO) were synthesized by a fast and high-yield Microwave-Assisted Polymer Synthesis (MAPS) technique; CL/EO values are determined by taking the ratios of the number of repeating units in the PCL and the PEG segments. The aggregation behavior of the copolymers was thoroughly investigated by means of surface tension (critical micellar concentration), dynamic light scattering (size, size distribution and zeta potential) and transmission electron microscopy (morphology). In general, the greater the central PEG segment, the larger the micelles formed. The physical stability was intimately associated with the molecular weight and the composition. Then, the encapsulation of RIF in the different copolymer families was evaluated, and the physical stability of the drug-loaded aggregates characterized. The micellar size appears as the most crucial property, this phenomenon being primarily controlled by the molecular weight of the PEG central block. Having expressed this, sufficiently high CL/EO ratios (and long PCL segments) are also demanded to attain stable micellar systems with cores that are large enough to host the bulky RIF molecule.

Surface active agents have been used in many pharmaceutical formulations for different purposes as penetration enhancers. In this study, the penetration enhancement activity of four nonionic surfactants from polyoxyethylene sorbitan fatty acid esters alone and in combination with some short-chain alcohols on red blood cells were investigated. Hemolysis at different concentrations of each nonionic surfactant (0.1, 0.2, 0.5, 1, and 2%) and ethanol, isopropyl alcohol, glycerol, and propylene glycol (0.5, 1, 2, 5, and 10% w/v) were investigated. Critical micelle concentration (CMC) and micellization thermodynamic parameters of tween 80 in presence of ethanol and glycerol at different concentrations were determined. The influence of the ethanol and glycerol on nonionic surfactant micelle formation was evaluated by determining CMC and micellization thermodynamic parameters of tween80 at different concentrations of alcohol-tween mixtures. The mixture of Tween 20 and glycerol have the lowest hemolytic activity while tween 80-ethanol mixture has the highest hemolysis activity. The self-aggregation of surfactant monomers was affected by short-chain alcohols. The structure breaking ability of alcohol and their interactions with the hydrophilic-hydrophobic groups of surfactants might be the main factors for changing the micelle formation. The CMCs of tween 80 was incremented by increasing the concentration of alcohol. The results indicated that by adding and increasing short chain alcohols the CMCs increased also the CMCs were increasing through raising the temperature (while in the presents of surfactants alone the CMCs decreased by raising temperature).

Basic knowledge of chemical events in the gaseous or liquid phase, as well as on surfaces, is required to determine the macroscopic process. The structure of ionic liquids were investigated using quantum chemistry. Cation and anion can bond together, according to the findings. Their binding and interaction energies reveal that they are produced by hydrogen bonds. The mechanism of a room temperature ionic liquid, such as BMIMCl (1-butyl-3-Methylimidazolium chloirde) monomer, was studied using Density functional theory (DFT) computations using the modern continum solvation model (IEFPCM-SMD). Ionic liquid [IL] contains both anions and cations, allowing for greater intermolecular interactions. By analyzing the relative minimum energy of BMIMCL in the presence and absence of water, we were able to establish the minimum energy structures and probable Cl anion binding sites in BMIMCL ionic liquid.

APG Alkylpolyglycosides ATR-IR Attenuated total reflectance-infrared CAC Critical aggregation concentration CED Cohesive-energy density CI Chemical ionization CMC Critical micelles concentration C + m /C − n Alkylammonium alkanoate CPBr Cetylpyridinium bromide (Hexadecylammonium bromide) CTAB Cetyltrimethylammonium bromide (Hexadecyltrimethylammonium bromide) CTAOH Cetyltrimethylammonium hydroxide (Hexadecyltrimethylammonium hydroxide) CxC14 Cyclohexylammonium tetradecanoate DLS Dynamic quasi-elastic light scattering DMF N,N-dimethylformamide DMSO Dimethylsulfoxide DNA Deoxyribonucleic acid DOPC Dioleoylphosphatidylcholine DOSY Diffusion ordered spectroscopy DTAB Dodecyltrimethylammonium bromide ESI Electrospray ionization FA Formamide FT-IR Fourier-transform infrared spectroscopy G-Hyd m N-alkylamino-1-deoxy-D-glucitol G-Hyd 8 N-octylamino-1-deoxy-D-glucitol G-Hyd 12 N-dodecylamino-1-deoxy-D-glucitol G-Hyd 16 N-hexadecylamino-1-deoxy-D-glucitol G-Hyd + m /C − n N-alkylammonium-1-deoxy-D-glucitol alkanoate Glyc Glycerol h Planck's constant (6.626.10 −34 Js) HRMS High resolution mass spectrometry L-Hyd N-alkylamino-1-deoxy-D-lactitol L-Hyd 12 N-dodecylamino-1-deoxy-D-lactitol L-Hyd 16 N-hexadecylamino-1-deoxy-D-lactitol v List of Synthesized Products 3a C + 8 /C − 8 Octylammonium octanoate 3b C + 8 /C − 12 Octylammonium dodecanoate 3c C + 12 /C − 8 Dodecylammonium octanoate 3d C + 12 /C − 12 Dodecylammonium dodecanoate 3e C + 8 /C − 16 Octylammonium hexadecanoate 3f C + 16 /C − 8 Hexadecylammonium octanoate 3g C + 16 /C − 16 Hexadecylammonium hexadecanoate 4a G-Hyd 8 N-octylamino-1-deoxy-D-glucitol 4b G-Hyd 12 N-dodecylamino-1-deoxy-D-glucitol 4c G-Hyd 16 N-hexadecylamino-1-deoxy-D-glucitol 5a G-Hyd + 8 /C − 12 N-octylammonium-1-deoxy-D-glucitol dodecanoate 5b G-Hyd + 12 /C − 8 N-dodecylammonium-1-deoxy-D-glucitol octanoate 5c G-Hyd + 8 /C − 16 N-octylammonium-1-deoxy-D-glucitol hexadecanoate 5d G-Hyd + 16 /C − 8 N-hexadecylammonium-1-deoxy-D-glucitol octanoate 5e G-Hyd + 16 /C − N-hexadecylammonium-1-deoxy-D-glucitol dodecanoate 5f G-Hyd + 12 /C − N-dodecylammonium-1-deoxy-D-glucitol hexadecanoate 5g G-Hyd + 12 /C − N-dodecylammonium-1-deoxy-D-glucitol octadecanoate 6 NbNH 2 Norbornene methyleneamine (Bicyclo[2,2,1]hept-5-ene-2-methyleneamine) 7 NbC14 Norbornene methyleneammonium tetradecanoate viii 3 Syntheses of the Catanionic Surfactants 3.1 Model Systems of the Alkylammonium Alkanoate Type. .. .. .. .. 3.2 Synthesis of N-amino-1-deoxy-D-glucitol G-Hyd m. .. .. .. .. .. . 3.3 Synthesis of Catanionic Associations of the G-Hyd + m /C − n Type. .. .. 3.4 Synthesis of Bicyclo[2,2,1]hept-5-ene-2-methyleneamine (NbNH 2). .. .

The aggregation behavior of cationic gemini surfactants with respect to variation in head group polarity and spacer length is studied through conductance, surface tension, viscosity, and small-angle neutron-scattering (SANS) measurements. The critical micellar concentration (cmc), average degree of micelle ionization (β ave), minimum area per molecule of surfactant at the air-water interface (A min), surface excess concentration (Γ max), and Gibb's free energy of micellization (G mic) of the surfactants were determined from conductance and surface tension data. The aggregation numbers (N), dimensions of micelles (b/a), effective fractional charge per monomer (α), and hydration of micelles (h E) were determined from SANS and viscosity data, respectively. The increasing head group polarity of gemini surfactant with spacer chain length of 4 methylene units promotes micellar growth, leading to a decrease in cmc, β ave , and G mic and an increase in N and b/a. This is well supported by the observed increase in hydration (h E) of micelles with increase in aggregation number (N) and dimension (b/a) of micelle.

A series of novel gemini cationic surfactants alkanediyl-α, ω-bis (hydroxyethylmethylhexadecylammonium bromide) with polymethylene spacer chain length of 4, 6, 8, and 10 carbon atoms was synthesized and characterized. Critical micellar concentrations of the gemini surfactants in aqueous solutions as determined by the surface tension and conductance measurements were observed to be in the range 1.39-3.63 µM. The critical micellar concentration was observed to increase initially with spacer length up to 6 methylene groups and to decrease thereafter with the increase in spacer length. The micellar microstructure in aqueous solutions examined through small angle neutron scattering (SANS) revealed that the extent of aggregation growth and variation in shapes of micelles strongly depend on head group polarity, spacer chain length, and temperature. The propensity to micellar growth with spacer chain length 4 was found to be much higher than with the longer spacer lengths. The fractional charge on the micelle increases with increased spacer chain length and temperature.

The purpose of this study was to determine whether human vasoactive intestinal peptide (VIP) aggregates in aqueous solution and, if so, whether the peptide interacts with a biomimetic phospholipid monolayer and increases surface pressure. Using a custom-made Teflon trough containing HEPES buffer (pH 7.4) at room temperature and a surface tensiometer, we found that the critical micellar concentration (CMC) of VIP is 0.4 M. Surface pressure of a dipalmitoylphosphatidylcholine (DPPC) monolayer spread over the HEPES buffer declined significantly over 120 min because of phospholipid decomposition. However, injection of VIP at concentrations above CMC into the subphase of the monolayer elicited a significant concentration-dependent increase in surface pressure that persisted for 120 min (P Ͻ 0.05). Unlike VIP, injection of [ 8 Arg]-vasopressin at an equimolar concentration only prevented the time-dependent decline in DPPC monolayer surface pressure. Taken together, these data indicate that human VIP aggregates in aqueous solution and expresses surface-active properties at physiological concentrations in vitro. We suggest that these attributes could have a role in modulating the bioactive effects of the peptide in vivo.

Novel glucose-based non-ionic gemini amphiphiles comprising two sugar head groups, two hydrophobic tails having chain length of C 12 , C 14 , and C 18 and a-CH 2-ArCH 2-spacer have been synthesized. The head groups of the geminis consist of glucose entities (with reducing function blocked in cyclic acetal group) connected through C-6 to tertiary amines. These amphiphiles were explored as reverse micellar systems, for the encapsulation of D-and L-enantiomers of ultraviolet-absorbing aromatic a-amino acids histidine (H), phenylalanine (F), tyrosine (Y) and tryptophan (W) in n-hexane, without any added water. Reverse micellar studies revealed that aromatic a-amino acids were encapsulated in the sequence H [ F [ Y [ W. In most cases, specifically for F, D-enantiomer was found better encapsulated than L-enantiomer in the reverse micellar probes of the gemini surfactants.

Research into the mechanisms of formation of granules produced from heterogeneous-wetting powder blends is still at an early stage. Granulation of non-wetting powders is a common problem in pharmaceutical applications. The discovery of liquid marbles by the spreading of non-wetting powder over a liquid droplet is a promising way to solve the wettability problem of non-wetting powder. Hollow granules are formed upon drying of liquid marbles. In this I would like to thank my supervisor Dr. Rachel Smith, for all her kind guidance, help and support during my research project. Rachel has shown enthusiasm, direction and assistance for which I am really thankful. My thanks also extend to my industrial supervisor Dr. Leon Farber, for his kind guidance and support throughout my research study at MSD, and beyond. Many thanks to Dr. Michael Gentzler, who has contributed toward my understanding and thought. I would also like to express gratitude to my second supervisor Dr. Alan Dunbar, for his advice on my doctoral development program. Many thanks go to Dr. Kate Pitt whose feedback on my writing has been invaluable, and Dr. Omid Tash, who put me in the right direction to develop the regime maps. Thanks must also go to the fabulous members of particle Technology Group. Thank you for all your support, for your feedback, for providing a great working environment, and for all the wonderful activities we have did. Thanks also extend to staff at the Formulation department of MSD for their kindness and support. Special thanks go to Victoria Kitching for giving feedback on my thesis. I would also like to thank the awesome technical staff at the University of Sheffield. I am grateful to the Higher Committee for Education Development in Iraq for providing the funding of my study. Finally, but most importantly, my deepest gratitude also goes to my mother, husband, sister and to my children for their moral support and love.

Background: Membrane proteins are privileged pharmaceutical targets for which the development of structure-based drug design is challenging. One underlying reason is the fact that detergents do not stabilize membrane domains as efficiently as natural lipids in membranes, often leading to a partial to complete loss of activity/stability during protein extraction and purification and preventing crystallization in an active conformation. Methodology/Principal Findings: Anionic calix[4]arene based detergents (C4Cn, n = 1-12) were designed to structure the membrane domains through hydrophobic interactions and a network of salt bridges with the basic residues found at the cytosol-membrane interface of membrane proteins. These compounds behave as surfactants, forming micelles of 5-24 nm, with the critical micellar concentration (CMC) being as expected sensitive to pH ranging from 0.05 to 1.5 mM. Both by 1 H NMR titration and Surface Tension titration experiments, the interaction of these molecules with the basic amino acids was confirmed. They extract membrane proteins from different origins behaving as mild detergents, leading to partial extraction in some cases. They also retain protein functionality, as shown for BmrA (Bacillus multidrug resistance ATP protein), a membrane multidrug-transporting ATPase, which is particularly sensitive to detergent extraction. These new detergents allow BmrA to bind daunorubicin with a Kd of 12 mM, a value similar to that observed after purification using dodecyl maltoside (DDM). They preserve the ATPase activity of BmrA (which resets the protein to its initial state after drug efflux) much more efficiently than SDS (sodium dodecyl sulphate), FC12 (Foscholine 12) or DDM. They also maintain in a functional state the C4Cn-extracted protein upon detergent exchange with FC12. Finally, they promote 3D-crystallization of the membrane protein. Conclusion/Significance: These compounds seem promising to extract in a functional state membrane proteins obeying the positive inside rule. In that context, they may contribute to the membrane protein crystallization field.

The ocular irritancy potential of surfactants of the anionic and non-ionic type, derived from lysine has been tested by the hen's egg test-choriollantoic membrane (HET-CAM) to correlate the potential irritation with the structure of the surfactant, in order to synthesize the less irritant surfactant for their use in the pharmaceutical and cosmetics industry. The anionic compounds, independently of the counterion, showed an irritant action higher than non-ionic surfactants. Among the anionic surfactants

The aggressiveness in terms of apogenic and necrotic activities of lysine-derived anionic surfactants towards a Ž. ␣ q mammalian cell line U937 were studied. We used N N-dioctanoyl lysine as the model surfactant with lysine, tris, Na or Li q as counterions. The aggressiveness of the different surfactants was assessed as the concentrations leading to apoptosis or necrosis after the cells were incubated in the presence of surfactants and then cultivated in their absence. Used in the same conditions, acetates associated with the same cations, had no effects on the cells. Our results show that the aggressiveness of the surfactants depended on the nature of the counterions: it was high when surfactants were associated with small counterions, and low with large counterions.

The effects of new synthetic lysine-derived anionic surfactants on human and rat erythrocytes were studied. The surfactants were salts of N a ,N o-dioctanoyl lysine with different counterions: lysine (77KK), tris (trishydroxymethyl amminomethane) (77KT), sodium (77KS), and lithium (77KL). 77KK and 77KT showed a biphasic hemolytic behavior in the erythrocytes. The surfactants 77KS and 77KL showed concentration-dependent hemolysis with a CH50 of about 3.4 and 2.6 mmol/l, respectively. 77KK and 77KT induced protection against hypotonic hemolysis in rat erythrocytes at the concentration which showed the least hemolytic activity under isotonic conditions. With human erythrocytes, 77KT did not show biphasic behavior in isotonic medium, but under hypotonic conditions biphasic behavior was present. Changes in shape of the erythrocyte, from discocytic to stomatocytic were observed after incubation with the anionic surfactants studied. Such shape changes Abbre6iations: CH50, concentration inducing 50% of hemolysis; CMC, critical micellar concentration; LDH, lactate dehydrogenase; Hb, hemoglobin; 77KL, lithium salt of N a ,N o-dioctanoyl lysine; 77KK, lysine salt of N a ,N o dioctanoyl lysine; PBS, phosphate buffered saline; 77KS, sodium salt of N a ,N o-dioctanoyl lysine; 77KT, tris salt of N a ,N o-dioctanoyl lysine.

The outer sphere electron transfer reaction of surfactant cobalt(III) complexes, Cis-[Co(en) 2 (4CNP)(C 12 H 25 NH 2)](ClO 4) 3 1, Cis-[Co(trien)(4CNP)(C 12 H 25 NH 2)](ClO 4) 3 2 and Cis-[Co(trien)(4AMP)(C 12 H 25 NH 2)](ClO 4) 3 3 (en: ethylenediamine, trien: triethylenetetramine, 4CNP: 4-cyanopyridine, 4AMP: 4-aminopyridine, C 12 H 25 NH 2 : dodecylamine) have been investigated by Fe 2+ ion in liposome vesicles (DPPC) and ionic liquids medium at different temperatures under pseudo first order conditions using an excess of the reductant. In the presence of ionic liquid medium the second order rate constant for this electron transfer reaction was found to increase with increasing concentration of ionic liquids. Below the phase transition temperature of DPPC, the rate decreased with increasing concentration of DPPC, while above the phase transition temperature the rate increased with increasing concentration of DPPC for the same complexes has also been studied. Experimentally the reactions were found to be second order and the electron transfer postulated as outer sphere. The results have been discussed in terms of increased hydrophobic effect, self aggregation and the presence of pyridine ligand containing 4-amino and 4-cyano substituent.

We studied the interaction of n-octyl-L-D-glucopyranoside-solubilized VIP receptors (VIPR) with wheat germ agglutinin and found that the addition of the lectin to the detergent extract led to the formation of aggregates that could be pelleted by high speed centrifugation. Resuspension of the pellet in the presence of the competing trisaccharide, N,NP,NQtriacetylchitotriose (TAC), dissociated the lectin from the complex without altering the precipitability of VIPR. The final pellet (referred to as TAC pellet) contained an average of 12% of total protein and 96% of total VIP binding activity with a typical rank order of potency for VIP-related peptides. Lipid analysis and electron microscopic examination indicated that the precipitated material was composed of lipid vesicles. VIPR molecules were shown to be integrally inserted in the liposomes because they could not be dissociated from the vesicles at pH 11 or with high salt concentration. By comparing the liposome-associated VIP binding activity in the presence and absence of detergent and by showing accessibility of VIPR to PNGase F, it was concluded that VIP binding sites were not simply trapped within the reconstituted vesicles but likely exposed at the external surface of the liposomes.

The reactivity of prednisolone (Pd) to gamma radiation in aqueous and organic solutions has been investigated using Cobalt 60 source in a Gammacell-220 and radiation doses of 0.25, 0.5, 1.0, 2.0, 3.0, 4.5, 6 and 9 KGy. The residual drug concentration was determined by HPLC method using 45:55 acetonitrile: water as mobile phase on a reversed phase column and UV detector at 254 nm. The degradation kinetics study showed an initial zero-order followed by complex reactions illustrated graphically as an overall first order kinetic. The study revealed that the drug was significantly more sensitive to gamma radiation in aqueous solutions than organic solvents, with degradation rates of 1.34 and 0.67 x 10-4 M/KGy for aqueous and propylene glycol solutions, respectively. The structure activity relationship of the organic solvents (ethanol, n-propanol, isopropanol, n-butanol, isobutanol, tertiary butanol, 1-3 propane-diol, propylene glycol and glycerin), as pure solvents has been studied. Although the difference was not significant, the alkyl chain length and branching increased the reactivity of the solvent to radiation. Moreover, the number and position of hydroxyl groups in the solvent structure have significantly increased its sensitivity to radiation which has been manifested as increased drug degradation. Isoropanol and tertiary butanol as free radical scavengers have shown variable protective effects for the drug against radiation. The role of different types of surfactants (sodium lauryl sulfate, Tween 80 and benzalkonium chloride) in drug protection against radiation in aqueous solutions suggested two different mechanisms. The first is the scavenging effect of the surfactant monomers below its CMC. Above CMC, a second mechanism may be involved, where the drug is expected to be located inside the formed micelles to different extents according to its affinity to the surfactant leading to more stabilization of the drug. The protective effect of surfactants was found to be in the order: sodium lauryl sulfate > Tween 80 ≥ benzalkonium chloride.

Fluorous chemistry [1] has become a new discipline, the history and paradigms of which are summarized in a recent Handbook [2]. Main streams include fluorous biphasic catalysis, fluorous synthesis and fluorous mixture synthesis, which are recently being supplemented with thermomorphic and confined fluorous systems. All branches of fluorous chemistry are based on the unique properties of perfluoroalkanes and related solvents, such as chemical inertness, immiscibility with water and most hydrocarbons, low refractive index and as a consequence low intermolecular forces. Noteworthy is the fact that the substitution of hydrogen by fluorine is the sole methodology to reduce the electronic polarizability and to make the molecule hard and to lower the boiling point [3]. Fluorophilic compounds represent a subclass of fluorous ones, displaying a fluorous partition coefficient, P FBS >1, measured between a c-CF 3 C 6 F 11-toluene solvent pair at 25 o C temperature; while all fluorous compounds have at least one perfluoroalkylchain or 'fluorous ponytail' (e.g. R fn = C n F 2n+1 , n = 1-10) in each molecule. Fluorophilic compounds can be designed effectively using the simple 'like dissolves like' rule or more complex mathematical expressions derived from thermodynamic models [1, 4]. Both the present practice and the future development of fluorous chemistry should be affected by the awareness of the environmental and health issues of the involved perfluoroalkyl-species, since the presence of perfluorooctanesulfonate (PFOS) and perfluorooctanecarboxylate (PFOA) in the environment have been detected globally, including blood plasma of nonoccupationally exposed humans too (Scheme 1) [5].

Capillary electrophoresis was used for determination of 6 fractions of caseins. Those fractions were measured in 144 samples of cow’s milk originated from the feeding experiment focused on explanation the influence of the feeding onto casein productions. In this work were separated 6 fraction of caseins first time with total resolution of the peaks. Capillary electrophoresis was applied for determination of short-chain organic acids during fermentation of wine must. It was compared the fermentation of must fermented by different yeast. The difference of profile short-chain organic acids during fermentation were not statistically significant. The once difference was in the utilisation of the malic acid and production of the lactic acid. A portable miniaturized system for medium pressure liquid chromatography was developed. The components were tested and system was used for the isocratic and gradient elution of various analytes (food dyes, parabens). New line of electroluminescent dio...

The apolipoproteins of insect lipophorin were dissociated in guanidinium chloride and isolated by gel permeation chromatography. Over 98% of the total lipid in lipophorin was associated with apolipophorin I (apoLp-I), thus suggesting this apolipoprotein to be the lipid binding component of the particle. ApoLp-I was delipidated with ethanol/ether and solubilized in buffer that contained radioactive lysophosphatidylcholine ([3H] LPC) above the critical micellar concentration. Sonic irradiation of radioactive phosphatidylcholine ([14C]PC) with [3H]LPC-solubilized apoLp-I a t a molar ratio of 318 resulted in reconstituted lipophorin I (RLp-I). [3H]LPC was bound to fatty acid free bovine serum albumin and was separated from RLp-I by density gradient ultracentrifugation and gel permeation chromatography. Negatively stained RLp-I particles were quasispherical with an average radius of 5 5 A, and their overall morphology and secondary structure were similar to those of native hemolymph lipophorin. The RLp-I particle had a p = 1.137 g/mL, a M , z 5.2 X lo5, and a ['4C]PC:apoLp-I molar ratio of 308. From the compositional analysis, molecular size, trypsinization, and lipolysis with phospholipase A,, we concluded that each RLp-I particle contained one molecule of apoLp-I and a monomolecular layer of [14C]PC. When injected into the hemolymph of adult moths in vivo, RLp-I was loaded with lipid, as judged by a decrease in its density both in the presence and in the absence of adipokinetic hormone. The similarities in morphology and immunology of RLp-I and native lipophorin, together with the ability of RLp-I to load lipid, suggest that reconstituted lipophorins may serve as models to probe lipophorin structure and function.

Sheep tail fat is a common frying oil in Iran due to its good flavor and stability. Deodorization is a high-temperature vacuum purification process for removing the volatile compounds from the edible fats and oils. In this paper, the effects of temperature, time, and ultrasound power on the quality attributes of sheep tail fat during the deodorization process were studied using response surface methodology. Variations of the acid value, peroxide value, iodine value, and saponification value, as well as extinction coefficient, were investigated. The best equations were created for the responses of acid value (R 2 = 0.9143, p < 0.0001), peroxide value (R 2 = 0.9862, p < 0.0001), iodine value (R 2 = 0.9670, p < 0.0001), refractive index (R 2 = 0.9816, p < 0.0001), saponification value (R 2 = 0.9345, p < 0.0001) and extinction coefficient (R 2 = 0.9562, p < 0.0001). Finally, the temperature of 200 ºC, the processing time of 80 min, and the ultrasound power of 307 W were recommended for the optimal conditions of sheep tail fat ultrasound-assisted deodorization.

Nano-size LiFePO4/C composite was synthesized via a modified solid state reaction method. Olive oil is used as carbon source. The conventional solid state process was modified by introducing two initial steps of slurry phase blending of the ingredients and solvent removal by rotary evaporation, so as to get an intimate mixing and homogenous dispersion of reactants and conductive carbon in the sample. Both structure and morphology of the LiFePO4/C composite sample have been characterized by X-ray diffraction (XRD), Mössbauer spectrometry, transmission electron microscopy (TEM) and Raman spectroscopy. The LiFePO4/C composite exhibited a high crystallinity. The particles of synthesized LiFePO4/C were fine and homogeneous in size, with an average diameter of 100nm. Since the thermal effect of laser irradiation may possibly alter material surface, particular attention has been paid in characterizing the structure and component of the material surface by Raman spectroscopy. Electrochemical measurements show that the LiFePO4/C composite cathode delivers an initial discharge capacity of 146 mAh g −1 between 2.5 and 4.3Vat a C/10 rate (a charger rated C/10 would return the battery capacity in 10 hours).