Dicarboxylic amino acid-based surfactants (N-dodecyl derivatives of -aminomalonate, -aspartate, and -glutamate) in combination with hexadecyltrimethylammonium bromide (HTAB) form a variety of ...aggregates. Composition and concentration-dependent mixtures exhibit liquid crystal, gel, precipitate, and clear isotropic phases. Liquid crystalline patterns, formed by surfactant mixtures, were identified by polarizing optical microscopy. FE-SEM studies reveal the existence of surface morphologies of different mixed aggregates. Phase transition and associated weight loss were found to depend on the composition where thermotropic behaviours were revealed through combined differential scanning calorimetry and thermogravimetric studies. Systems comprising more than 60 mol% HTAB demonstrate shear-thinning behaviour. Gels cause insignificant toxicity to human peripheral lymphocytes and irritation to bare mouse skin; they do not display the symptoms of cutaneous irritation, neutrophilic invasion, and inflammation (erythema, edema, and skin thinning) as evidenced by cumulative irritancy index score. Gels also exhibit substantial antibacterial effects on Staphylococcus aureus, a potent causative agent of skin and soft tissue infections, suggesting its possible application as a vehicle for topical dermatological drug delivery.
Aggregation studies of anionic surfactant sodium dodecyl sulphate (SDS) was investigated in aqueous 1-butyl-3-methylimidazolium chloride bmimCl and N-butyl-N-methyl pyrrolidinium tetrafluoroborate ...bmpBF4 ionic liquid (IL) solutions respectively. Systems were studied by surface tension, conductance, UV-VIS absorption/emission spectroscopy and dynamic light scattering. Critical micelle concentration (CMC) values gradually decreased with increasing IL concentration which indicates synergistic interaction between ILs and SDS. Gibbs free energy change results demonstrated spontaneous micellization induced by ILs; however the effect of ILs were not similar to the corresponding regular salts (NaCl and NaBF4). Aggregation number (n) of micelles, determined by fluorescence quenching method, indicate that the ‘n’ values increase with increasing ILs concentration, induced by the oppositely charged IL cation. Size of the micelles, determined by dynamic light scattering studies, increased with increasing ILs concentration, which were due to the formation of larger aggregates; the aggregates are considered to be comprised of the anionic surfactant with a substantial proportion of ILs cation as the bound counter ions. Such studies are considered to shed further light in the fundamentals of IL induced micellization as well as in different practical applications.
Effect of 1-butyl-3-methylimidazolium chloride ionic liquid (bmimCl, IL) on the monolayer/bilayer of either soy-phosphatidylcholine (SPC) or hydrogenated soy-phosphatidylcholine (HSPC), in ...combination with 30 mol% cholesterol (Chol), were investigated. Impact of IL on monolayers were explored by measuring the surface pressure (π)-area (A) isotherm with a Langmuir-surface balance. Lift-off area (A0) of the monomolecular films gradually increased A0(HSPC+IL) > A0(SPC+IL), collapse pressures (πc) decreased and passed through minima πc(HSPC+IL) > πc(SPC+IL) with increasing IL concentration (IL). Minimum molecular area (Amin) increased monotonously and compression moduli (Cs−1) followed the sequence (HSPC+IL) > (SPC+IL) at a particular π with respect to IL. Dynamic light scattering studies were carried out to determine the hydrodynamic diameter (dh), zeta potential (Z.P.) and polydispersity index (PDI) values while fluorescence anisotropy studies, using 7-hydroxycoumarin and 1,6-diphenyl-1,3,5-hexatriene, could reveal the micro-viscosity of liposomes. Increased size and rigidity, induced by IL, suggest the formation of leak-proof, condensed liposomes. Disruption of vesicles induced by IL were observed from transmission electron microscopic (TEM) studies. IL induced disintegration of liposome and kinetics of subsequent formation of adsorbed monolayer were accomplished by surface pressure-time isotherms. IL-induced liposomes were substantially less toxic as revealed by MTT assay. These liposomes are considered to be safely used as effective and controlled drug delivery systems.
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Physicochemical properties of lipid monolayer depend on its composition where a blend of lipids exhibit superior behaviour than the individual component. Surface pressure (π) – area (A) isotherms of ...mixed monolayer (PCmix) formed by dipalmitoylphosphatidylcholine (DPPC), palmitoleylphosphatidylcholine (POPC), soyphosphatidylcholine (SPC) and hydrogenated soy phosphatidylcholine (HSPC) in combination with 30 mole % cholesterol (Chol) were obtained by using Langmuir trough. Effects of dipalmitoylphosphatidyethanolamine (DPPE) on its mutual miscibility at the air-water interface with DPPC + Chol, POPC + Chol, HSPC + Chol and SPC + Chol were also investigated separately, followed by studying the effects of DPPE and dipalmitoylphosphatidylglycerol (DPPG) to PCmix + Chol and PCmix + DPPE + Chol respectively. Lift-off area, minimum molecular area, excess molecular area, collapse pressure, Gibbs free energy of interfacial mixing, compressibility modulii values were evaluated by analyzing the isotherms. Deviations from the ideal mixing behaviours were dependent on the composition of the lipid blends. Surface dilatational rheology studies could assess monolayer elasticity, whereas the film morphologies were analysed by Brewster angle microscopic (BAM) studies. DPPC induced formation of condensed monolayer, whereas film rigidity was increased with the incorporation of DPPE and DPPG into mixed systems. Interactions among the lipid components of the investigated mixed systems were thoroughly discussed from the point of view of polar head and acyl chain saturation and obtained results follow the sequence: PCmix + DPPE + DPPG + Chol > PCmix + DPPE + Chol > individual PC + DPPE + Chol which could be translated into the bilayer studies. Such investigation of mixed lipid is important for class of its own composition and combined results are expected to contribute in better understanding the interaction of selected lipid in proposed blend.
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Epidemiological evidence support that diet rich in polyphenolic compound reduce the risk of cardio vascular disease (CVD). Polyphenols (500-4000 Da) are the main organic constituent presenting with ...5-7 phenolic ring with >12 phenolic hydroxyl groups, water soluble plant derived compound. These compounds are also able to generate NO from vascular endothelium. The aim of the mini review was to investigate the role of the most commonly consumed polyphenols in the pathophisiology of the risk of ischemic stroke and CVD. Polyphenol can reduce endothelial dysfunction, in the development of atherosclerosis with the inhibition of the aggregation of platelet and lowering blood pressure. This paper reviews the current advances in polyphenols in food, with emphasising on health aspects on the basis of the published literature, which may provide some guidance for researchers in further investigations and for industries in developing practical health agents.
Bile salt derived nontoxic surface-active ionic liquids (SAILs), 1-butyl-3-methylimidazolium cholate (bmimC) and deoxycholate (bmimDC) were synthesized by reacting bmim tetrafluoroborate separately ...with sodium cholate (NaC) and sodium deoxycholate (NaDC) which were subsequently characterized by FTIR, 1H-NMR, 13C-NMR, HRMS, PXRD, and TGA-DTA studies. Interfacial and aggregation behavior of the SAILs were assessed by surface tension, conductance, pyrene fluorescence, dynamic light scattering, and isothermal titration calorimetric studies. Critical micelle concentration values were substantially lower than their precursor sodium salts. SAILs were less surface active than their corresponding sodium salts due to enhanced aqueous solubility induced by the ionic liquid cation. Both the aggregation number and size of the SAIL micelles were higher/larger where the SAIL micelles were more compact than NaC/NaDC. Exothermic changes in the enthalpy of micellization were higher for SAILs, where the micellization processes were found to be entropy driven. Such comprehensive studies can shed further light on the microstructure, besides the fundamental understanding on SAIL aggregation. The combined advantages of surfactant and ionic liquid in the SAILs can result in superior amphiphilic characteristics. Such nontoxic aggregates are capable to enhance the limited solubility of organic compounds in water besides their possible uses in catalysis, drug delivery, and energy storage, etc.
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The effects of two ionic liquids (ILs), 1-butyl-3-methylimidazolium tetrafluoroborate (bmimBF4) and 1-butyl-1-methyl pyrrolidinium tetrafluoroborate (bmpBF4), on a mixture of phospholipids (PLs) ...1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC), 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE), and 1,2-dipalmitoyl-sn-glycero-3-phosphoglycerol (DPPG) (6:3:1, M/M/M, 70% PL) in combination with 30 mol % cholesterol (CHOL) were investigated in the form of a solvent-spread monolayer and bilayer (vesicle). Surface pressure (π)–area (A) isotherm studies, using a Langmuir surface balance, revealed the formation of an expanded monolayer, while the cationic moiety of the IL molecules could electrostatically and hydrophobically bind to the PLs on the palisade layer. Turbidity, dynamic light scattering (size, ζ-potential, and polydispersity index), electron microscopy, small-angle X-ray/neutron scattering, fluorescence spectroscopy, and differential scanning calorimetric studies were carried out to evaluate the effects of IL on the structural organization of bilayer in the vesicles. The ILs could induce vesicle aggregation by acting as a “glue” at lower concentrations (<1.5 mM), while at higher concentrations, the ILs disrupt the bilayer structure. Besides, ILs could result in the thinning of the bilayer, evidenced from the scattering studies. Steady-state fluorescence anisotropy and lifetime studies suggest asymmetric insertion of ILs into the lipid bilayer. MTT assay using human blood lymphocytes indicates the safe application of vesicles in the presence of ILs, with a minimal toxicity of up to 2.5 mM IL in the dispersion. These results are proposed to have applications in the field of drug delivery systems with benign environmental impact.
Interfacial and aggregation behavior of sodium cholate (NaC) and sodium deoxycholate (NaDC) in aqueous ionic liquid (IL, 1-butyl-3-methylimidazolium tetrafluoroborate) medium were investigated. ...Studies were also carried out in the presence of NaBF
4
. Both IL and NaBF
4
reduce the critical micelle concentration (CMC) of bile salts, determined by surface tension, conductance, and fluorescence spectroscopic techniques; effect of NaBF
4
is more prominent than IL. CMC of NaC was higher than NaDC because of its higher hydrophilicity. IL, in addition to its salt-like behavior, results in associative interaction with the bile salts. Surface excess (Г
max
), surface pressure at the CMC (π
CMC
) were evaluated from surface tension data. Г
max
and π
CMC
values gradually decreased with increasing the IL and NaBF
4
concentration. Negative Gibbs free energy change for micellization (ΔG
0
mic
) and interfacial adsorption (ΔG
0
ads
) indicate spontaneity of micellization and interfacial adsorption, however to different magnitude. Fraction of counter ion dissociation, evaluated from conductance data, systematically decreased with increasing IL and NaBF
4
concentration. Aggregation number, determined by fluorescence quenching method, increased with increasing IL and NaBF
4
concentration that are in consonance with the size of the aggregates, determined by dynamic light scattering study. IL induced the formation of larger facial aggregates by bile salts; the effect was more imperative in case of NaDC than NaC. In case of NaBF
4
the opposite trend was recorded. Such systems are considered to have potential application where the dual benefit of both a surfactant and an IL are warranted.
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•Imidazolium/pyrrolidinium-dodecyl sulfate were synthesized and characterised.•Surface active ionic liquids (SAILs) have lower CMC and surface activity than SDS.•Larger size and ...aggregation number of SAILs are contributed by IL counter cations.•Spontaneous micellization of SAILs are entropy controlled processes.•SAILs exhibit dual advantages of ionic liquid and surfactant.
Salt free surface active ionic liquids (SAILs), 1-butyl-3-methylimidazolium dodecyl sulfate (bmimDS) and N-butyl-N-methylpyrrolidinium dodecyl sulfate (bmpDS) were synthesised by stoichiometric mixing of ionic liquid (IL) and sodium dodecyl sulfate (SDS). SAILs were characterised by FTIR, 1H NMR, 13C NMR and thermogravimetric analysis and differential thermal analysis (TGA-DTA). Interfacial and aggregation behavior of the SAILs were investigated by surface tension, conductance, UV–visible absorption, emission spectroscopy, dynamic light scattering and isothermal titration calorimetric studies. Results were compared with the precursor surfactant SDS. Critical micelle concentration (CMC) of the surfactants followed the sequence: SDS > bmpDS > bmimDS. Lower surface excess values of SAILs were due to electrostatic interaction between IL cation and DS-, besides the higher aqueous solubility of DS-, induced by the IL cations. Negative Gibbs free energy of micellization and higher fraction of counter ion binding values further support the proposition. Aggregation number (n) and size (dh) of the micelles were determined by fluorescence quenching and dynamic light scattering studies respectively; both ‘n’ and ‘dh’ values were higher for SAILs than SDS (bmimDS > bmpDS > SDS). SAIL aggregates, although larger in size with higher aggregation number, were more compact than SDS micelles. Enthalpies of micellization, being exothermic in nature, were higher for SAILs although the micellization processes were entropically controlled. SAILs are considered to have dual advantages of surfactant and IL with substantial decrease in toxicity level.
Abstract : Aggregation studies of anionic surfactant sodium dodecyl sulphate (SDS) was investigated in aqueous 1-butyl-3-methylimidazolium chloride bmimCl and N-butyl-N-methyl pyrrolidinium ...tetrafluoroborate bmpBF4 ionic liquid (IL) solutions respectively. Systems were studied by surface tension, conductance, UV-VIS absorption / emission spectroscopy and dynamic light scattering. Critical micelle concentration (CMC) values gradually decreased with increasing IL concentration which indicates synergistic interaction between ILs and SDS. Gibbs free energy change results demonstrated spontaneous micellization induced by ILs ; however the effect of ILs were not similar to the corresponding regular salts (NaCl and NaBF4). Aggregation number (n) of micelles, determined by fluorescence quenching method, indicate that the 'n' values increase with increasing ILs concentration, induced by the oppositely charged IL cation. Size of the micelles, determined by dynamic light scattering studies, increased with increasing ILs concentration, which were due to the formation of larger aggregates ; the aggregates are considered to be comprised of the anionic surfactant with a substantial proportion of ILs cation as the bound counter ions. Such studies are considered to shed further light in the fundamentals of IL induced micellization as well as in different practical applications.
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