Study of interaction between cationic surfactant (CTAB) and paracetamol by electrical conductivity, tensiometric and spectroscopic methods

Thermodynamic Insights of the Molecular Interactions of Dopamine (Neurotransmitter) with Anionic Surfactant in Non-Aqueous Media

This study was aimed at establishing the interactions prevailing in an anionic surfactant, sodium dodecyl sulfate, and dopamine hydrochloride in an alcoholic (ethanol) media by using volumetric, conductometric, and tensiometric techniques. Various methods were utilized to estimate the critical micelle concentration (cmc) values at different temperatures. The entire methods yielded the same cmc values. The corresponding thermodynamic parameters viz. the standard free energy of micellization (Gmico), enthalpy of micellization (Hmico), and entropy of micellization (Smico) were predicted by applying the pseudo-phase separation model. The experimental density data at different temperatures (298.15 K, 303.15 K, 308.15 K, and 313.15 K) were utilized to estimate the apparent molar volumes (Vϕo) at an infinite dilution, apparent molar volumes (Vφcmc) at the critical micelle concentration, and apparent molar volumes (ΔVφm) upon micellization. Various micellar and interfacial parameters, for example, the surface excess concentration (Γmax), standard Gibbs free energy of adsorption at the interface (ΔGoad), and the minimum surface area per molecule (Amin), were appraised using the surface tension data. The results were used to interpret the intermolecular interactions prevailing in the mixed systems under the specified experimental conditions.

A recent overview of surfactant-drug interactions and their importance

This review focuses on the self-aggregation properties of different drugs, as well as on their interaction with anionic, cationic, and gemini surfactants. The interaction of drugs with surfactants has been reviewed concerning conductivity, surface tension, viscosity, density, and UV-Vis spectrophotometric measurements, and their relation with critical micelle concentration (CMC), cloud point, and binding constant. The conductivity measurement technique is used for the micellization of ionic surfactants. Cloud point studies can be used for the non-ionic, and also for certain ionic surfactants. Usually, surface tension studies are mostly employed for non-ionic surfactants. The degree of dissociation that is determined is used to evaluate thermodynamic parameters of micellization at various temperatures. The effect of external parameters like temperature, salt, solvent, pH, etc., is discussed for thermodynamics parameters using recent experimental works on drug-surfactant interactions. Consequences of drug-surfactant interaction, condition of drugs during interaction with surfactants, and applications of drug-surfactant interaction are being generalized which reflects current and future potential uses of drug-surfactant interactions.

Modeling of Association Properties of Cetylpyridinium Halides (Cl, Br) and their Influence on Liberation and Rheological and pH Balances of Hydrogels with Ibuprofen

The paper studies the influences of two cationic surfactants - cetylpyridinium chloride (CPCl) and cetylpyridinium bromide (CPBr) - at concentrations 10-times below and 10-times above the CMC - at 258C-408C on the release of ibuprofen from hydrogels, rheological properties and pH. The association of surfactants in the water solutions was studied by conductometry. It was found that the temperature dependences of the surfactants’ CMCs are not linear and the CMCs of CPCl are higher than that of CPBr. The concentrations of the polymer (chitosan) and the drug were kept constant. Amounts of the released drug increased with the increasing temperature. From the hydrogels with CPBr and CPCl, whose surfactant concentration was below the respective CMC, higher amounts of the active ingredient were released than from the hydrogels with surfactant concentrations above the respective CMC. It is shown that for increasing temperature the hydrogels exhibit gradual transition for pseudo plastic to thixotropic system, what is advantageous for their practical application. The hydrogels’ pH values were in the interval 5.10-5.46, which is ideal for their application on the skin and for the chitosan swelling. The presented topic is a precondition of synthesis of the on-line and off-line control algorithms of an optimal release kinetics, elaborated by the authors.

Natural Ergot Alkaloids in Ocular Pharmacotherapy: Known Molecules for Novel Nanoparticle-Based Delivery Systems

Several pharmacological properties are attributed to ergot alkaloids as a result of their antibacterial, antiproliferative, and antioxidant effects. Although known for their biomedical applications (e.g., for the treatment of glaucoma), most ergot alkaloids exhibit high toxicological risk and may even be lethal to humans and animals. Their pharmacological profile results from the structural similarity between lysergic acid-derived compounds and noradrenalin, dopamine, and serotonin neurotransmitters. To reduce their toxicological risk, while increasing their bioavailability, improved delivery systems were proposed. This review discusses the safety aspects of using ergot alkaloids in ocular pharmacology and proposes the development of lipid and polymeric nanoparticles for the topical administration of these drugs to enhance their therapeutic efficacy for the treatment of glaucoma.

Soft Cationic Nanoparticles for Drug Delivery: Production and Cytotoxicity of Solid Lipid Nanoparticles (SLNs)

The surface properties of nanoparticles have decisive influence on their interaction with biological barriers (i.e., living cells), being the concentration and type of surfactant factors to have into account. As a result of different molecular structure, charge, and degree of lipophilicity, different surfactants may interact differently with the cell membrane exhibiting different degrees of cytotoxicity. In this work, the cytotoxicity of two cationic solid lipid nanoparticles (SLNs), differing in the cationic lipids used as surfactants CTAB (cetyltrimethylammonium bromide) or DDAB (dimethyldioctadecylammonium bromide), referred as CTAB-SLNs and DDAB-SLNs, respectively, was assessed against five different human cell lines (Caco-2, HepG2, MCF-7, SV-80, and Y-79). Results showed that the cationic lipids used in SLN production highly influenced the cytotoxic profile of the particles, with CTAB-SLNs being highly cytotoxic even at low concentrations (IC50 < 10 µg/mL, expressed as CTAB amount). DDAB-SLNs produced much lower cytotoxicity, even at longer exposure time (IC50 from 284.06 ± 17.01 µg/mL (SV-80) to 869.88 ± 62.45 µg/mL (MCF-7), at 48 h). To the best of our knowledge, this is the first report that compares the cytotoxic profile of CTAB-SLNs and DDAB-SLNs based on the concentration and time of exposure, using different cell lines. In conclusion, the choice of the right surfactant for biological applications influences the biocompatibility of the nanoparticles. Regardless the type of drug delivery system, not only the cytotoxicity of the drug-loaded nanoparticles should be assessed, but also the blank (non-loaded) nanoparticles as their surface properties play a decisive role both in vitro and in vivo.

Self-assembly of sodium dodecylsulfate and dodecyltrimethylammonium bromide mixed surfactants with dyes in aqueous mixtures

The micellar property of mixed surfactant systems, cationic (dodecyltrimethylammonium bromide, DTAB) and anionic (sodium dodecylsulfate, SDS) surfactants with variable molar ratios in aqueous system has been reported by using surface tension and conductivity measurements at T = 293.15, 298.15 and 303.15 K. DTAB concentrations are varied from 1.0 × 10^-4 to 3 × 10^-4 mol l^-1 in 1.0 × 10^-2 mol l^-1 SDS solution while the SDS concentration is varied from 1.0 × 10^-3 to 1.5 × 10^-2 mol l^-1 in approximately 5.0 × 10^-3 mol l^-1 DTAB, so that such concentrations of DTAB-SDS (DTAB-rich) and SDS-DTAB (SDS-rich) solutions were chosen 3 : 1 ratio. The critical micellar concentration, as well as surface and thermodynamic properties for DTAB-rich and SDS-rich solutions, were evaluated by the surface tension (γ) and conductivity (κ) methods. The pseudo phase separation model was coupled with the dissociated Margules model for synergism. The Krafft temperature behaviour and optical analysis of mixed surfactants are studied using conductivity and UV-Vis spectroscopy, respectively. The dispersibility and stability of DTAB-rich and SDS-rich solutions with and without dyes (2.5 × 10^-5 mol l^-1 of methyl orange and methylene blue) are carried out by using UV-Vis spectroscopy and dynamic light scattering.

Facile synthesis of mesoporous carbon microspheres/graphene composites in situ for application in supercapacitors

MCMG were in situ synthesized via a soft template method and subsequent thermal reduction by using CTAB as structure-directing agent, AMP and GO as carbon sources. As-prepared MCMG samples exhibited excellent electrochemical performances.

Study of Intermolecular Interactions of CTAB with Amino Acids at Different Temperatures: A Multi Technique Approach

The densities, ρ, viscosities, η and specific conductivities κ, of (0.0002, 0.0004, 0.0006 and 0.0008 m) CTAB in 0.1 m aqueous valine, leucine and isoleucine were measured at different temperatures. The measured data were used to calculate various useful thermodynamic parameters. A complete characterization of any mixture can be performed by means of these thermodynamic properties. The apparent molar volume, ϕv , partial molar volume, ϕ v 0 $\phi _v^0$ and partial molar isobaric expansibilities, ϕ E 0 , $\phi _E^0,$ were calculated using density data. The viscosity data were analyzed using Jones–Dole equation to obtain viscosity coefficients, A- and B-, free energy of activation per mole of solvent, Δμ 1°∗, and solute, Δμ 2°∗, enthalpy, ΔH ∗ and entropy, ΔS ∗ of activation of viscous flow. Measuring the changes in these properties has been found to be an excellent qualitative and quantitative way to obtain information regarding the molecular structure and intermolecular interactions occurring in these mixtures. Various structure-making/breaking ability of solute (cetyltrimethylammonium bromide) in presence of aqueous amino acid solutions were discussed. In addition, fluorescence study using pyrene as a photophysical probe has been carried out, the results of which support the conclusions obtained from other techniques.