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Herein, in the presence of electrolytes, the cloud points (CPs) of the mixture of a conventional uncharged amphiphile (triton X-100 (TX-100)) and promethazine hydrochloride (PMH; phenothiazine medicine) were measured and explained in great details. The CP values of the employed surfactant + PMH system were reduced with enhancing salts contents (NaCl, Na2SO4, NH4Cl, and (NH4)2SO4)), while the CP values of the study system followed the trend: Na2SO4 < NaCl and (NH4)2SO4 < NH4Cl. The different thermodynamic parameters of phase separation, including standard free energy (ΔG0c), enthalpy (ΔH0c), and entropy (ΔS0c) changes were also calculated and discussed elaborately. The values of free energy change (ΔG0c) were obtained to be positive, indicating that the clouding phenomena are non-spontaneous. Different transfer properties (free energy (ΔG0c.t), enthalpy (ΔH0c,t), and entropy (ΔS0c,t) of transfer), intrinsic enthalpy gain (ΔH0,*c) and compensation temperature (Tc) of the inspected system have also been assessed and discussed. [ABSTRACT FROM AUTHOR]

An experiment using surface tension was conducted to investigate the interactions of promethazine hydrochloride (PMT), with TX-165, at the interface in different ratios and solvents (water/50 mmol/kg NaCl, and 500 mmol/kg urea) at 298.15 K. A thorough FTIR study of the employed pure and mixed system was also conducted in the aqueous solution. PMT is a medication employed to manage and cure allergic conditions. Usually, NaCl media improved the surface properties of singular and mixed components over aqueous media, resulting in synergistic/attractive interactions among ingredients. TX-165's composition at mixed monolayer (Xs 1), surface excess concentration (Γmax), pC20, activity coefficient, and so on were evaluated. The achieved activity coefficient values are attained below one in each case, indicating the attractive interactions amongst ingredients. A negative Gibbs energy of adsorption (ΔGoads) was obtained all through, indicating spontaneity in the process. A negative excess free energy (ΔGsex) was found at the mixed interface of PMT+TX-165, showing a higher surface stability of mixed monolayer than pure component monolayer. FTIR spectroscopy is used to study the spectrum of single and mixed amphiphiles to validate the interaction between PMT and TX-165. This study suggested that TX-165 surfactant might behave as an able antidepressant drug delivery agent. [ABSTRACT FROM AUTHOR]

Micelles serve as a replica for the investigation of bio-membranes as physicochemical association of drugs with micelles is envisioned as their interconnection with bio-membranes. Micellization properties of promethazine hydrochloride (PMT) with TX-165 (a nonionic surfactant) in aqueous, 50 mmolkg−1 NaCl and 500 mmolkg−1 urea solutions were analysed in detail using surface tension measuring tool. PMT is employed as an analgesic, anticholinergic, sedative, antihistaminic as well as antipsychotic drug. UV-visible spectroscopy is also utilised to evaluate PMT-TX-165 interactions in an aqueous solution. Pure constituent and their mixtures (PMT + TX-165) of each composition showed lower cmc value in NaCl than in the aqueous system, while urea-containing solutions showed higher cmc value. Increasing the mole fraction (α1) of TX-165 in mixed systems increases the interaction between the employed constituents (PMT and TX-165). The evaluated Gibbs free energy (Δ G m ∘) values of singular, and mixed system in each media were attained negative that uncovering that each system depicted the spontaneity of micellization. Various thermodynamic parameters were examined and discussed thoroughly. A UV-visible measurement also confirms that the components interact in treaty with surface tension measurements. Based on the results of this study, TX-165 was designed in a forthright manner, which could be an efficient drug delivery vehicle for phenothiazine drugs. [ABSTRACT FROM AUTHOR]

Herein, the aggregation manners of polyvinyl alcohol (PVA) with tetradecyltrimethylammonium bromide (TTAB) in alcohols/diols media containing various concentrations and at several temperatures were performed using the conductivity measurement technique. Different physico-chemical parameters, such as critical micelle concentration (CMC), fraction of bound counter ions (β) and thermodynamic properties (ΔGom, ΔHom, ΔSom, and ΔCom) for the TTAB + PVA mixture in aqueous solutions of EtOH (EtOH), 1-propanol (1-PrOH), ethylene glycol (EG), and propylene glycol (PrG), have been determined. The CMC values were found to undergo a decrease in 1-PrOH in comparison to the values obtained in aqueous media, but in EtOH, the CMC value firstly decreases, touches the lowest point, and then exhibits an upsurge with further increase of the percentage of EtOH. The observed greater CMC values in diols media disclose that the micelle formation of TTAB + PVA mixture is delayed in the manifestation of diols. The CMC values of TTAB + PVA mixture have also been observed to vary with the change of study temperature. The negative values of ΔG0m were obtained for all circumstances suggesting a spontaneous aggregation phenomenon of TTAB + PVA system. The values of ΔH0m and ΔS0m dictate that the PVA molecule interacts exclusively with TTAB through the formation of hydrogen bonding, ion-dipole, and hydrophobic interaction. Furthermore, the standard molar heat capacity (ΔC0m), compensation temperature (Tc), intrinsic enthalpy gain (ΔH0,*m), and the thermodynamic properties of transfer (ΔG0m.tr, ΔH0m.tr. and ΔS0m.tr.) for the studied system were assessed and demonstrated with appropriate explanations. [ABSTRACT FROM AUTHOR]

Cefixime trihydrate (CMT) has the usages to treat the bacterial infections of urinary tract, throat, ear & tonsils. Herein, the current investigation describes the interaction of CMT with dodecyltrimethylammonium Bromide (DTAB) by means of the conductivity measurement method in H2O and aq. solutions of NaBr, Na2SO4, and Na3PO4. The experiments were carried out at 310.55 K for several concentrations of CMT/ salts and temperatures of 300.55−320.55 K for one particular concentration of CMT/ salts employed. In every case, a single critical micelle concentration (CMC) has been achieved. The addition of CMT augments the aggregation of DTAB. The CMC values of the DTAB + CMT mixture undergo a decrease in attendance of electrolytes in comparison to water medium. In the manifestation of electrolytes, the CMC values of DTAB + CMT mixed systems at 310.55 K and ionic strength of 1 mmol kg−1 follow the order: CMC (H2O + NaBr) > CMC (H2O + Na2SO4) > CMC (H2O + Na3PO4). The negative ΔG°m values indicated that the micellization of DTAB + CMT mixture was spontaneous. The -ΔH°m and +ΔS°m values disclose that the assembly of DTAB + CMT mixture in aqueous medium is both enthalpy & entropy-controlled process. The thermodynamics of transfer and enthalpy-entropy compensation have also been described in the ongoing study. [ABSTRACT FROM AUTHOR]

Cationic quaternary ammonium gemini surfactants were synthesized by mixing N,N-dimethylcetylamine and α,ω-dibromoalkane. The synthesized products were characterized by C, H, N elemental and 1H NMR analyses. The critical micelle concentration (CMC) of these surfactants with and without additives was calculated by means of the conductivity technique. The role of the synthesized quaternary ammonium geminis in the reaction was investigated by a UV–vis spectroscopy. The rate constant (kψ) was determined at different gemini concentrations and plotted graphically as kψ vs. [16–s–16]. Additionally, the influence of other reaction parameters (viz., reactants, pH, and temperature) was investigated. The binding constants were also determined (KA for [Cu(II)–His]+ and KB for ninhydrin). The resulting kψ–[16–s–16] plot can be understood in terms of a pseudo-phase model of micelles. [ABSTRACT FROM AUTHOR]

In this article, the study of metal-amino acid complex and ninhydrin reaction was examined in gemini micellar solution using a UV-visible spectrophotometric measurement. The role of varying amounts of gemini micellar systems on rate constant of the study was investigated. Initially, rate constant (kψ) enhances, below cmc and levelling-off areas are, then, noticed up to 400 × 10−5 mol dm−3. Later, gemini offers a third region of fast enhancement kψ above 400 × 10−5 mol dm−3. Gemini surfactant series provided more efficient implications on the study than pure water and their monomeric traditional surfactant system. The values of rate constant, kψ, were determined under a set of different experimental reaction situations with the help of a computer-based procedure. Such unfamiliar behaviour developed by gemini micellar solutions was treated by pseudo-phase model of micellar activity. An electrical conductometric measurement was employed to measure critical micellar concentration (cmc) of pure gemini micellar solutions and mixed systems. Several activation parameters were also determined by Eyring's equation and different constants. Data obtained confirmed that lower values of activation enthalpy (ΔH#) with large negative activation entropy (ΔS#) were attained in gemini than aqueous. A plausible reaction mechanism of the study has been discussed and proposed. [ABSTRACT FROM AUTHOR]

We investigated the influence of an additive (50 mmol kg–1 NaCl/300 mmol kg–1 urea [U]) on the aggregation of amphiphilic promethazine hydrochloride (PMH) drug and cationic hydrotrope–aniline hydrochloride (AnHCl) mixtures at various temperatures and ratios. The drug PMH is mostly used for the treatment of allergic symptoms. The obtained critical micelle concentration (cmc) values are well below the cmcid (ideal cmc) value, which confirms interactions between components PMH and AnHCl in the solution mixture. The micellar mole fraction (X1Rub, X1Rod, and X1id) of the first component (AnHCl) was evaluated using different models, which suggested greater involvement of AnHCl in mixed micelles (as expected); besides, the obtained micellar mole fraction values increase with increase in the mole fraction (α1) of AnHCl. The interaction parameter (β) values obtained were negative, which confirms attractive interaction or synergism among the components. Activity coefficients (f1Rub [AnHCl] and f2Rub [PMH]) values are always found below one confirming the nonideality as well as attractive interaction between the components. Different physicochemical parameters evaluated suggested attractive interaction between the components (PMH and AnHCl) in all studied solvents; however, in salt media, the interaction increases to some extent, whereas in urea media, it decreases to some extent. Diverse thermodynamic parameters (Gibbs free energy [ΔGm0], enthalpy [ΔHm0], and entropy [ΔSm0]) of micellization were computed and discussed separately. The excess free energy (∆GexRub) values of all systems were negative, suggesting higher stability of formed mixed micelles as compared with singular‐component micelles. [ABSTRACT FROM AUTHOR]

In this work, a series of alkanediyl-α,ω–type gemini micelles symbolized as 16-s-16 (s = spacer) was synthesized. Synthesized products were characterized by 1H NMR technique. By conductivity method, cmc of these surfactants was determined by measuring specific electrical conductivity at different concentrations. Alkanediyl-α,ω–type gemini micelles–catalyzed interaction between [Ni(II)-Trp]+ complex and ninhydrin has been studied with the help of spectrophotometric studies. The catalytic implication of gemini micelles on rate constant (kψ) in ninhydrin and [Ni(II)-Trp]+ has been explored and discussed at 343 K and pH 5.0. Catalyzing behavior obtained by geminis confirmed that they influenced the study remarkably over their monomeric conventional counterpart. Results were also suggested that small amount of geminis at concentration below cmc was sufficient to induce the reaction more than aqueous. Though, 16-4-16 is detected to catalyze the work more among geminis and follows the order at each concentration as: 16-4-16 > 16-5-16 > 16-6-16. This catalytic implication produced by gemini micelles can efficiently be deduced using pseudophase model for micellar activity. In addition, by varying temperatures, several thermodynamic quantities were evaluated. A lower enthalpy value, ΔH#, with significant negative entropy value, ΔS#, is acquired in geminis than aqueous system. [ABSTRACT FROM AUTHOR]

Herein, we investigated the micelle formation of mixed systems of the antipsychotic drug, chlorpromazine hydrochloride (CPZ), and the bile salt, sodium deoxycholate (NaDC), both in the absence and presence of NaCl by tensiometry. To understand the aggregation behaviour of the mixture of these two amphiphiles, we calculated various micellar and interfacial parameters using the theories of Clint, Rubingh, Rosen and Motomura. The calculated interaction parameters indicate an attractive interaction between the two amphiphiles both in the absence and presence of salt. The results were discussed with regard to the use of bile salt as a promising drug carrier for CPZ and the improvement of its bioavailability. [ABSTRACT FROM AUTHOR]

Present work concerns with the interaction of ninhydrin with zinc(II) complex of tryptophan ([Zn(II)-Trp]+) in the three dicationic gemini surfactant systems. To record critical micellar concentration (CMC) and absorbance, we have used Systronics conductivity meter and UV-visible spectrophotometer, respectively. Experiment opens up the fractional- and first-order paths in ninhydrin and complex, respectively. Gemini micellar medium is found more superior over aqueous medium. Rate constant (kψ) vs. [gemini] plot shows the unusual role of geminis on kψ. kψ increases with gemini concentration (at concentrations lower than the CMC, part I) and leveling-off regions obtain (concentration up to 400 × 10−5 mol dm−3, part II). Characteristics of part I and part II are just the same as that of conventional surfactant. Later, gemini produces a third region of increasing kψ at higher concentrations ([gemini] > 400 × 10−5 mol dm−3, part III). Detail and systematic elucidation about the effect of surfactants are mentioned and discussed in the text. Binding constants (KS for [Zn(II)-Trp]+ and KN for ninhydrin) and rate constant (km in geminis) were determined by nonlinear least squares regression technique. The kinetic results acquired can reasonably be interpreted by pseudo-phase model of surfactant micelles. [ABSTRACT FROM AUTHOR]

In the current study, interaction of a metal ion‐coordinated dipeptide complex and ninhydrin was examined in the alkanediyl‐α,ω‐bis‐type gemini surfactant system. This work was performed as a function of reactants (ninhydrin and metal‐dipeptide complex), surfactants, temperature, and pH. Different techniques including UV–vis spectrophotometry were used to carry out the experiments. The kψ–values were evaluated in the presence of alkanediyl‐α,ω‐bis‐type gemini surfactants. A first‐order path in the metal‐dipeptide complex and a fractional‐order path in ninhydrin were noticed. To illustrate the quantitative analysis of kψ–[gemini] profiles, a pseudophase model of micelles was employed. Thermodynamic parameters were also evaluated and explained. By the observed outcomes, a probable mechanism was suggested and discussed in detail. [ABSTRACT FROM AUTHOR]

[Display omitted] • Interaction of amitriptyline hydrochloride (AMT) with TX-165 in aqueous/NaCl/urea media. • Surface tension/FT-IR/molecular dynamics simulation techniques were used. • TX-165 was found in higher fraction than AMT in the mixed micelles. • Thermodynamic studies revealed that mixed micelle formation is spontaneous. • FT-IR investigation also detected interaction amongst AMT and TX-165. Herein, mixed micellization behavior of the antidepressant drug amitriptyline hydrochloride (AMT) + nonionic surfactant triton X-165 (TX-165) mixtures were investigated thoroughly using various techniques. Dullness and depression are treated with AMT. Effect of different media of fixed concentration (aq./50 mmol kg−1 NaCl/500 mmol kg−1 urea) was exposed on the AMT interaction with TX-165 by tensiometry technique at 298.15 K. For AMT + TX-165 mixture, the assessed critical micelles concentration (cmc) was achieved lower compared with calculated ideal cmc value (cmc *) of respective system as a result of the nonideal behavior of mixed system. AMT and TX-165 interaction in aq. NaCl solvent was more pronounced than aqueous solution but was less apparent when using urea solution, i.e., AMT interacted with TX-165 in different solvents as given order: NaCl > aqueous > urea. As a result of TX-165′s higher hydrophobicity, TX-165 accomplished to have a more fraction in mixed micelles compared with AMT. The micellar composition of TX-165 (X 1 R ub ) was attained larger than the corresponding employed mole fraction of TX-165 (α 1) with exception at α 1 = 0.9. It was found that in all cases, the interaction parameter (β Rub) was negative, indicating a synergistic/attractive interaction between AMT and TX-165. Thermodynamic studies have revealed that the formation of mixed micelles of AMT + TX-165 is worthwhile, as well as spontaneous. The Gibb's free energy (Δ G m °) value of studied system was found negative in each employed solvent showing the spontaneity of system, and spontaneity was highest with NaCl and lowest with urea than in aqueous solution. FT-IR spectra revealed the shifting of wavelength of constituent mixture compared with singular employed constituent, which elucidates the interaction amongst them. The interactions between AMT and TX-165 were revealed on the atomic scale using molecular dynamics simulation, demonstrating good agreement with the results of the experiments. Considering these results, a drug delivery system might be developed. [ABSTRACT FROM AUTHOR]

Studies of the interaction between the zinc-peptide complex ([Zn(II)-Gly-Gly]+) and ninhydrin in aqueous and CTAB surfactant media were executed by the means of UV-visible spectrophotometry. The reaction rates (kobs and kψ) were determined in both media by varying different parameters such as pH, temperature and the concentration of the reactants and CTAB. The micellar binding constants and activation parameters were also calculated. The catalytic activity in the CTAB medium was found to be better than in the aqueous medium on the title reaction. The catalysis by CTAB is treated quantitatively by applying the model of the kinetic pseudo-phase of the micelle. Variation of the rate constant with the change of the CTAB concentration was used for the calculation of several kinetic parameters such as the binding constants (KB and KNin) and the micellar rate constant km. On basis of the experimental results, a probable mechanism is proposed. [ABSTRACT FROM AUTHOR]

Abstract At present work, role of cetyltrimethylammonium bromide (CTAB) surfactant micelles on kinetics of zinc-glycylleucine [Zn(II)-Gly-Leu]+ and ninhydrin has been studied. The effect of different variables, viz., ninhydrin, [Zn(II)-Gly-Leu]+ complex, temperature and pH was also undertaken on the title reaction. Role of CTAB on kinetics of complex and ninhydrin has been carried out using spectrophotometric technique. CTAB was observed more efficient for the [Zn(II)-Gly-Leu]+ and ninhydrin reaction than aqueous. The rate constant k ψ -values enhanced with increase in [CTAB] from 0 to 50 mol dm−3 and further increase has a slow decrease in rate. Conductometric technique was used to evaluate critical micelle concentration (cmc) of surfactant. The relationship of rate constant (k ψ) with CTAB concentration was discussed and described in sufficient details. Analysis of kinetic data was rationalized in terms of model of surfactant micelles (pseudo-phase). Various parameters have also been evaluated including thermodynamic and binding constant. Highlights • Ninhydrin is mostly used for its remarkable high sensitivity. • Catalytic activity of CTAB was found more than aqueous on the reaction. • Peptide plays significant role as signal transmitters in cell communications. • Work may bring in an innovative direction of studying kinetics of ninhydrin reaction. [ABSTRACT FROM AUTHOR]

Highlights • Interaction between bile salt mixtures has been investigated. • The critical micelle concentration and interaction parameter were determined. • The synergistic behavior was observed for the NaC + NaDC mixtures while NaC + NaTC show antagonism. • Thermodynamic properties of micellization were calculated. • Aggregation number (N), Stern-Volmer constant and dielectric constant were computed. Abstract Surface tension and steady-state fluorescence measurements have been done for mixtures of bile salts, namely sodium cholate (NaC) + sodium tourocholate (NaTC) and sodium cholate + sodium de-oxycholate (NaDC) at 298.15 K. From the experimental critical micelle concentration (cmc), the interaction parameter has been figured utilizing the regular solution theory proposed by Rubingh for mixed surfactant systems. The ideal cmc values and thermodynamic properties of micellization were evaluated. The Rosen model was used to calculate the various surface parameters. The interaction between NaC + NaDC surfactants was observed to be stronger than in NaC + NaTC. The stronger interaction of NaC + NaDC was also confirmed by fluorescence data. The steady-state fluorescence quenching method was applied to compute the micelle aggregation number, Stern-Volmer constant and micropolarity of single and mixed bile salt systems. [ABSTRACT FROM AUTHOR]

Abstract Herein, we have reported the studies of interaction between ninhydrin and glycylleucine (Gly-Leu) dipeptide in cationic Gemini surfactants (m-s-m; m = 16; s = 4, 5, 6) by using spectrophotometric technique. The rate constant values, k ψ , were determined at different temperatures and pH. The effect of concentration of reactants and surfactants was also carried out on the title reaction. It was also observed that the reaction was accelerated and catalyzed by 16- s -16 Gemini surfactants even at low critical micelle concentration (cmc) value of surfactants. The variation of Gemini surfactants on the reaction of ninhydrin with glycylleucine has been analyzed with the help pseudo-phase model of surfactants proposed by Menger and Portnoy and developed by Bunton. The binding constants for reactants (ninhydrin and Gly-Leu) have been computed using a computer based program. Highlights • Ninhydrin is applied for quantitative estimation of amino groups. • Pseudo-phase model was used to explain the plots of k ψ -[16- s -16]. • Reaction was accelerated and catalyzed by 16- s -16 even at low cmc value. • Low use of Geminis allows them to fall into green surfactant category. [ABSTRACT FROM AUTHOR]

Chlorpromazine is a psychiatric medication that belongs to the class of drugs called phenothiazine antipsychotics. It works by helping to restore the balance of certain natural substances in the brain. In the current study, the micellization behavior of chlorpromazine hydrochloride (CPZ) drug with Pluronic F-127 in the absence/presence of 0.1 M NaCl at 298 K temperature, has been studied. Tensiometric profile, for pure and mixtures of CPZ + F-127, generally consists of two breaks, whereas a single break is presents in pure CPZ tensiometric isotherm. Various bulk and interfacial parameters, such as critical micelle concentration ( cmc ), interaction parameter ( β ), maximum surface excess concentration ( Γ max ), effectiveness of surface tension reduction ( π cmc ), and other surface parameters at the interface have been estimated using a surface tension technique. Theories of Clint, Rosen, and Rubingh have been used to determine the theoretical cmc , interaction between amphiphiles at interface and micellar state of aggregation, and the composition of aggregates. The experimental cmc values of the mixed systems are lower than that of ideal one ( cmc ideal ) over the entire mole fraction range of CPZ. A negative departure of cmc values from the ideal indicate that the mixed micelle formation occurs due to favorable mixing (synergistic interactions) in the mixed states. Several thermodynamic parameters have also been predicted from those theories. The interaction between the CPZ and Pluronic F–127 was also determined by extensive steady–state fluorescence measurements. [ABSTRACT FROM AUTHOR]

Interaction of anionic bile salt sodium taurocholate (NaTaC) and anionic anti-inflammatory drug sodium salt of ibuprofen (NaIBU) in aqueous solutions together with in occurrence of 100 mmmol kg −1 NaCl and 250 mmmol kg −1 urea (NH2CONH2) using tensiometric and fluorometric techniques at 298.15 K temperature has been studied. A tensiometry study disclosed decreasing in surface tension ( γ ) along with critical micelle concentration ( cmc ) of NaIBU and NaTaC mixture, signifying a noteworthy interaction between studied components. Salt decreases the cmc of amphiphiles whereas urea increases their cmc in comparison to the aqueous solution. The solution mixture of NaIBU and NaTaC shows lower cmc value as compared to ideal cmc ( cmc id ) value indicating the non-ideality in the current studied systems. Other parameters regarding tensiometric technique such as micellar mole fraction of mixed micelles/mixed interface ( X 1 m / X 1 σ ), micellar/surface interaction parameter ( β m / β σ ), activity coefficients ( f 1 m / f 1 σ and f 2 m / f 2 σ ) of the mixed micelles/mixed interface, surface excess concentration ( Γ max ), excess Gibbs energy of mixed monolayer/mixed micelle formation ( Δ G ex σ / Δ G ex m ) etc. were estimated. The non-ideality of mixing expressed in terms of the interaction parameter ( β m / β σ ). Various thermodynamic parameters for current systems in all different media were obtained and discussed in detail. The aggregation number ( N agg ), as well as other related parameters regarding fluorescence study, were also evaluated. The higher values of N agg show the being of hydrophobic interactions along with sustains synergism. [ABSTRACT FROM AUTHOR]

Aggregation as well as thermodynamic behavior of amphiphilic imipramine hydrochloride (IMH) drug (antidepressant) and anionic surfactant (sodium dodecyl sulfate [NaDS] as well as sodium dodecylbenzenesulfonate [NaDBS]) mixtures as a function of solution composition in aqueous solutions have been evaluated by conductometry method at different temperatures. Surfactant (NaDS and NaDBS) employed in the current study is anionic in nature. Various theoretical models such as Clint, Rubingh, Motomura, and Rodenas were employed to gain information regarding the type of interaction between the components in the solution mixtures. The value of micellar mole fraction evaluated by different utilized models is found to be more for IMH-NaDBS mixtures in comparison with IMH-NaDS mixtures, signifying that participation of NaDBS is more in mixed micelles as compared with NaDS. Owing to the different charge of employed drug and surfactant, which sources high synergistic results in the mixed system comparative to the possessions of their pure compounds, means here anionic surfactants were elected in favor of the quantitation of cationic drug. The value of interaction parameters (β) was also evaluated by employing the Rubingh's model. The values of Gibbs free energy (ΔG0 m) for all systems attained to be negative in all studied systems showing that the systems are spontaneous in nature. [ABSTRACT FROM AUTHOR]

Interactions between anionic drug sodium salt of ibuprofen (IBU) and nonionic surfactant Triton X-114 (TX-114) micelles have been explored by means of surface tension, fluorometry and 1 H NMR techniques in aqueous and in the occurrence of 250 mmol kg −1 urea (NH 2 CONH 2 ). IBU is anti-inflammatory drug having analgesic as well as antipyretic property. The various mixed micelles, mixed monolayer as well as thermodynamic parameters like critical micelle concentration ( cmc ), interaction parameter in solution/interface ( β m / β σ ), maximum surface excess concentration ( Γ max ), Gibb's free energy of micellization (Δ G m ), Gibb's free energy of adsorption (Δ G ads ), excess free energy of aggregation/interface ( Δ G ex m / Δ G ex σ ) etc. have been estimated as well as discussed. Due to the presence of urea cmc values of pure as well as mixed amphiphiles systems increases owing to enrichment in the surface electron density of the micelles or mixed micelles. The values of β m/ β σ were found to be negative in solution/interface at all studied composition showing the attractive interaction between the constituent in both media (aqueous/250 mmol kg −1 urea). The negative values of Δ G m and Δ G ads demonstrate that micelle formation, as well as adsorption at the air/water interfacial surface, is energetically supportive. Mixed interfacial surface are wealthy in TX-114, showing a stable as well as packed adsorbed mixed surfaces of a solution. The micelle aggregation numbers ( N agg) and various others related parameters were evaluated by means of fluorescence quenching method that indicate the contribution of TX-114 was always more than that of the drug (IBU). The interactions between the studied components were additionally studied by 1 H NMR spectroscopic method which recommended that drug and surfactant interact via hydrophobic interaction in absence and occurrence of NH 2 CONH 2 . [ABSTRACT FROM AUTHOR]

Studies of interaction between chromium-glycylglycine complex ([Cr(III)-Gly-Gly] 2 + ) and ninhydrin in 16- s -16 gemini surfactants were executed at various composition of substrates and temperatures. The effect of pH was also performed on the title reaction. The rate constant values have been determined in the presence of geminis. Studies reveal that the reaction has same first- and fractional-order path in metal-dipeptide and [ninhydrin] in gemini surfactants to that of aqueous medium. Investigation of effect of gemini surfactants were carried out on the [Cr(III)-Gly-Gly] 2 + and ninhydrin reaction. The detailed activities/behaviors of geminis on the reaction are described in the text. The various parameters such as enthalpy of activation (Δ H # ), entropy of activation (Δ S # ), micelle-substrate constant ( K X ), micelle-ninhydrin constant ( K Y ) and second-order rate constants ( k m ) have been evaluated. Variation in rates of the reaction in the presence gemini surfactants was analyzed quantitatively by pseudo-phase model. [ABSTRACT FROM AUTHOR]

Herein, we have synthesized and characterized dicationic Gemini surfactants. The effect of their micelles on the rate constant of ninhydrin with [Cu(II)-Gly-Gly]+ complex reaction was investigated under pseudo-first-order-conditions. Experiments were carried out by means of spectrophotometry. First- and fractional-order dependencies on [Cu(II)-Gly-Gly]+ and ninhydrin, respectively, were found. The results indicated that the efficiency of micellar catalysis by Gemini surfactants was significantly higher as compared to single-chained surfactant cetyltrimethylammonium bromide, CTAB. The Gemini surfactant produces a catalytic effect and leveling-off regions (just like CTAB) on the reaction rate. Later, Gemini with higher concentrations gives a third region of increasing kψ. The effect of surfactants was rationalized by hydrophobic and electrostatic interactions. The observed kinetic effects are explained by applying the Menger-Portnoy model. [ABSTRACT FROM AUTHOR]

Herein, we have studied the interaction between cationic surfactant (conventional [myristyltrimethylammonium bromide, MTAB] as well as gemini surfactant 1, 4-butanediyl-α, ω-bis(dimethyltetradecylammonium bromide) (14-4-14)) and anti-inflammatory sodium salt of ibuprofen (IBU) drug in aqueous solutions by using tensiometry method at 298.15 K. The means of the interaction of drugs by added foreign materials is of paramount importance in the drug delivery. Ibuprofen is used for the relief of pain, fever, and swelling. From this study we have evaluated different parameters, for example, critical micelle concentration ( cmc), micellar mole fraction of mixed micelles/mixed interface ( X1m/ X1σ), micellar/surface interaction parameter ( βm/ βσ), activity coefficients ( f1m/ f1σ and f2m/ f2σ) of the mixed micelles/mixed interface, excess Gibbs free energy of mixed monolayer/mixed micelle formation ( [ABSTRACT FROM AUTHOR]

In the current work, we have examined the interaction activities of Pluronic F-68 with cationic conventional, cetyltrimethylammonium bromide (CTAB), and gemini surfactant, pentanediyl-1, 5-bis(dimethylcetylammonium bromide), (16-5-16) by means of surface tension and conductivity measurements. The critical micelle concentration (cmc) values of pure 16-5-16 and CTAB have been evaluated tensiometrically and conductometrically, while thecmcvalues of pure F-68 and binary mixtures were determined only from the surface tension plots. Various interfacial and micellar parameters including surface excess concentration (Γmax), minimum area per molecule (Amin), surface pressure atcmc(πcmc), packing parameter (p), and interaction parameter (β) have been estimated and discussed in detail. Various thermodynamic parameters including Gibbs free energy of micellization (), standard free energy of adsorption at the air–water interface (), excess free energy of micellization (ΔGex), and molar free energy at the maximum adsorption achieved atcmc(Gmin) have been calculated. [ABSTRACT FROM PUBLISHER]

This paper deals with a comprehensive study of the mixed micellization and adsorption behavior of mixed systems enclosing an amphiphilic antidepressant drug nortriptyline hydrochloride (NOT) and Triton X-114 (TX-114) (nonionic surfactant) in aqueous/urea (500 mmol·kg−1 and 1000 mmol·kg−1) solutions by tensiometric method. The NOT is used for the cure of depression. For comparison purpose cmc value of pure drug NOT was also evaluated by conductimetric technique. Different theoretical models like Clint, Rubingh, and Rosen were used to get information about the nature of interaction between the components in bulk and at the interface. Because of the occurrence of urea increase in the surface charge of the micelles was obtained resulting a delay of the micelles formation. The cmc values of the mixed systems of NOT and TX-114 were found to be in between the cmc values of pure components, which signify nonideal mixed system having attractive interactions in the absence and presence of urea. Various parameters such as micellar mole fractions of TX-114 ( X1m, X1σ) in solution and at interface, interaction parameter ( βm/ βσ) in solution and at interface, and activity coefficient in solution and at interface were evaluated and discussed using Rubingh's and Rosen's models. Surface excess ( Γmax) increases that means minimum area per head group ( Amin) decreases as mole fraction ( α1) of TX-114 increases in the absence/presence of urea. Different thermodynamic parameters have been calculated and discussed. The ∆ G0m values achieved are all negative both in the absence and occurrence of urea. [ABSTRACT FROM AUTHOR]

The interactions of serum albumins with a variety of drugs have expected immense interest currently owing to their considerable achieve in the biomedical area. In the current study, we have accounted the interactions between clomipramine hydrochloride (CLP) drug and human serum albumin (HSA) using various techniques such as UV-visible, fluorescence as well as circular dichroism (CD) at different temperatures (298.15, 310.15 and 318.15 K). CLP is a tricyclic antidepressant which is used to treat obsessive compulsive disorder. The outcomes of the current examination under the physiological circumstances suggested a static type of binding takes place between the CLP and HSA having binding constants of 10 4 L/mol. The evaluated thermodynamic parameters, inferred that reaction was an endothermic and spontaneous process, and hydrophobic together with electrostatic interactions are the main binding forces engaged in the formation of the HSA-CLP complex. According to Förster's theory, the distance ( r 0 ) between donor and acceptor was achieved to be 3.09 nm. The count of binding sites for binding of CLP on HSA was obtained to be around one. Adding of CLP causes the quenching of HSA fluorescence and a red shift at both excitation wavelengths (280 and 295 nm) owing to the hydrophobic interaction between drug and HSA. Circular dichroism (CD) spectra of HSA confirmed considerable alteration in the conformation of protein structure in the attendance of CLP. Therefore, the results obtained herein will be of biological importance in pharmacology as well as clinical medicine. [ABSTRACT FROM AUTHOR]

Herein, we report the kinetic study of nickel-glycylglycine with ninhydrin in alkanediyl-α,ω-gemini (m = 16 and s = 4, 5, 6) surfactant system using UV–vis spectrophotometer. From the results, different rates, binding constants and thermodynamic parameters were evaluated. The critical micelle concentration (cmc) value of geminis with and without both the substrates (ninhydrin and nickel-glycylglycine) was determined by conductivity measurements. The reaction kinetics show first- and fractional-order dependencies on nickel-glycylglycine and ninhydrin, respectively. Effect of gemini surfactants on the title reaction was also seen and pointed out that they are superior over their corresponding conventional surfactant. The catalytic role of gemini surfactants has been discussed in detail. Quantitative analysis of kinetic data was explained by applying Menger-Portnoy model of the micelles. [ABSTRACT FROM AUTHOR]

The interaction between promethazine hydrochloride (PMH) drug and sodium dodecyl sulfate (NaDS) have been carried out conductometrically at various temperatures and concentration to examine the monomeric as well as micellar phases of aqueous solutions of mixed systems in absence and attendance of urea (NH 2 CONH 2 ). PMH is belonged to the group of drugs called phenothiazines and is employed to care for allergy symptoms. Urea increases the cmc value because of enhancement in the surface charge of the micelles/mixed micelles. Relevant parameters were evaluated using the various theoretical models for binary mixed systems. The values of micellar mole fraction ( X 1 m ) and the ideal micellar mole fraction ( X 1 id ) were found to higher than the corresponding mole fraction ( α 1 ) of surfactant. The micellar interaction parameters ( β ), were determined from the critical micelle concentration ( cmc ) values using the approach of Rubingh's regular solution theory. Clint's model was also used to explain the nonideal behavior of the systems. In presence of urea the interaction between the studied components decreases. The evaluated excess free energy (Δ G ex Rub ) explains the more stability of mixed micelles in comparison to micelles of the pure component; the stability decreases in attendance of urea. Also, activity coefficients ( f 1 and f 2 ) are always less than unity suggesting non-ideality in the mixed solution. The Δ G 0 m for all studied systems were found out to be negative i.e., micellization processes are energetically favourable. [ABSTRACT FROM AUTHOR]

The mixed micelle formation between tetradecyltrimethylammonium bromide (TTAB) and benzyldimethylhexadecylammonium chloride (BDHAC) has been investigated in the absence as well as attendance of urea using conductivity technique. The evaluated values were examined in accordance with Rubingh model. The obtained values of critical micelle concentration ( cmc ) were smaller than cmc id values suggesting attractive interactions between the constituents of solution. The micellar mole fractions ( X 1 Rub ) of BDHAC, estimated by Rubingh model, were always higher than their ideal values ( X 1 id ) suggesting the high contributions of BDHAC in mixtures of TTAB and BDHAC. Interaction parameter ( β ) value was found to be negative showing an attractive interaction between the studied components. Activity coefficients ( f 1 Rub and f 2 Rub ) were always smaller than one in all cases and it indicates the attractive interaction between TTAB and BDHAC. The values of Δ G m o are found to be negative in all the cases which indicate the spontaneous formation of micelle. The values of Δ H 0 m are negative in all cases indicating the exothermic process. The values of Δ S 0 m are positive in case of aqueous medium and 500 mmol·kg − 1 urea solutions but found to be negative in attendance of 1000 mmol·kg − 1 urea. The values of excess free energy of micellization (Δ G ex Rub ) were also estimated and achieved to be negative showing the stability of mixed micelles. [ABSTRACT FROM AUTHOR]

This study reports the influence of non-ionic surfactants (TX-100 and TX-114) on the CPZ by surface tension, fluorescence and UV–vis spectra to explore their applications as drug delivery vehicles. The synergism is indicated by the values of the interaction parameters and activity coefficients, which are negative and less than unity, respectively. The ideal micellar mole fraction values of CPZ are less than the experimental values, confirming the high contribution of CPZ in mixed systems. The stability of these mixed systems is demonstrated by negative free energies of mixing. [ABSTRACT FROM AUTHOR]

Aqueous/salt/urea micellar solutions of amphiphilic antidepressant drug amitriptyline hydrochloride (AMT) and anionic surfactant sodium dodecylbenzenesulfonate (SDBS) have been examined by conductivity and fluorescence measurements at different temperatures and composition. From the conductometric study, values of critical micelle concentration ( cmc ) of drug have been evaluated and analyzed in terms of effect of surfactant on the hydrophobic nature of AMT–SDBS complex. The values of critical micelle concentration ( cmc ) and other aggregation parameters, micellar mole fraction ( X 1 ) and interaction parameters ( β ) were obtained and discussed in detail. In mixtures of AMT and SDBS, the synergistic interactions in mixed micelles formation increases with the raise in mole fraction of surfactant in absence and attendance of salt/urea. Thermodynamic parameters of the mixtures in aqueous as well as in salt/urea solution have been evaluated by means of a pseudo-phase model. The effect of NaCl shows the salting-out effect, which promotes aggregate formation of AMT and SDBS as well as their mixed systems at lower concentration relative to aqueous solution. The micelle aggregation number ( N agg ) of drug increases with the raise in surfactant mole fraction in mixtures. N agg value of individual and mixed amphiphiles rises in the presence of electrolyte while reduces in the occurrence of urea. [ABSTRACT FROM AUTHOR]

Herein, the interactions between the sodium salt of ibuprofen (IBU) with nonionic surfactant-BRIJ-56 were investigated at the interface as well as in the bulk phase (solution) in the existence and nonexistence of urea (250 mM). In the present study, tensiometric and fluorometric techniques have been utilized to investigate the association and micro-environmental properties of mixed systems. Various models (such as Clint, Rubingh, Maeda, etc.) were employed to obtain information regarding the nature of interaction between the components in bulk as well as at the interface. The critical micelle concentration (cmc) of pure amphiphiles and their mixed system increases in the existence of urea due to enhancement in the surface charge of the micelles. The urea activities have been explored on account of diverse aspects, such as the salvation of head groups and hydrophobic interactions. The aggregation number, micropolarity, and apparent dielectric constant of pure and mixed systems were investigated using steady-state fluorescence spectroscopy. A variety of energetic parameters (for instance the standard Gibbs free energy of micellization, Gibbs free energy of adsorption, and Gibbs excess energy) have been evaluated for further insight of urea action. The Δvalues achieved are all negative, both in the absence and in the presence of urea. [ABSTRACT FROM AUTHOR]

The current work deals with the mixed micellization phenomena of surface active promazine hydrochloride (PMZ) drug with cationic hydrotropes (para-toluidine hydrochloride and ortho-toluidine hydrochloride) in absence and occurrence of 50 mmol kg 1 NaCl at five different temperature (293.15-313.15 K). PMZ is an amphiphilic phenothiazine drug and employed for the cure of mania and schizophrenia. Conductometry measurement was employed to gain a detailed picture of the interactions between drug and hydrotrope molecules. The experimental data were analyzed according to different mixing models within the outline of the pseudophase separation model. The evaluated values of critical micelle concentration (cmc) were found to be inferior than cmcid values signifying attractive interactions involving the both components in the solutions. NaCl further reduces the cmc of pure amphiphiles and their mixed systems as a result of screening of the electrostatic repulsion between the polar head groups. The micellar mole fractions (X1) of hydrotropes evaluated by various proposed models were constantly more than ideal values (Xid 1) signifying high involvements of hydrotrope in mixed micelles. Activity coefficients (fRub 1 and fRub 2) were always below one in all cases signifying synergism in mixed micelles. Thermodynamic parameters favor the process of micellization which is found to be entropy driven. The negative values of free energies of mixing demonstrated the stability of the mixed systems of drug and hydrotrope. [ABSTRACT FROM AUTHOR]

Micellization (aggregation) phenomenon of amphiphilic phenothiazine drug promazine hydrochloride (PMZ) and sodium dodecylbenzenesulfonate (SDBS) mixtures in absence and attendance of 50 mmol∙kg−1 NaCl (salt)/300 mmol∙kg−1 urea was investigated conductometrically at five various temperatures (293.15-318.15 K) at gaps of T = 5 K. PMZ is employed for the cure of mania and schizophrenia. The (CMC) values have been evaluated and defined in terms of hydrophobicity and hydrophilicity of PMZ and SDBS in aqueous and nonaqueous solutions. With increasing the temperature, the CMC first increases then decreases. At 303.15 K, the maximum CMC values were obtained in absence and presence of NaCl/urea. NaCl reduces the CMC of pure amphiphiles and their mixtures while urea increases. Various physicochemical parameters such as CMCid (ideal ), micellar mole fraction of SDBS ( X1) (calculated by different proposed models), and interaction parameter have been evaluated and discussed in detail. The values of degree of dissociation ( g) and CMC of the micelles were utilized to evaluate the different thermodynamic parameters. Activity coefficients ( f1 and f2) and excess free energy of micellization (Δ Gex) values were also evaluated. All outcomes obtained herein show attractive interactions in the mixtures of PMZ and SDBS. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Present work deals with studies of ninhydrin (N) and phenylalanine (Phe) in cationic gemini micellar system by spectrophotometer under diverge kinetic environments. The results of the current study follow fractional-order in N and first-order in Phe. The study is intensely catalyzed by gemini surfactant (GS) system and rate constants (k ψ) are enriched even though at [GS] lower than critical micelle concentration (cmc). The noticed enhancement in rates between reactant molecules and gemini is attributed to hydrophobic and electrostatic interactions. To interpret the influence of various [GS], ranging from (1–3000) x 10−5 mol dm−3, on k ψ , a model so-called pseudo-phase originally proposed by Berezin et al. and improved by Bunton was applied. Various parameters and constants (like binding constants, thermodynamic parameters and micellar rate constants) have been evaluated. Under the present kinetic condition, a probable reaction mechanism between N and Phe is recommended. The conductivities of pure gemini and the presence of reactants at two temperatures, i.e., at 303 K and 343 K were measured using a conductivity instrument. The cmc of pure geminis in the current case determined at 303 K is consistent with those data reported, earlier. [Display omitted] [ABSTRACT FROM AUTHOR]

• Results favor to association of premicelle/micelle between the reactants and surfactant. • Optimum situations are obtained in geminis by studying impact of several factors on rate. • A decent matching of rates (k ψ and k ψcal) approves applicability of pseudo-phase model. Herein, catalytic impact of aqueous-micellar solution of twin headed 16- s -16 (s = spacer) gemini surfactants (GS) was measured in the study of ninhydrin (nin) with Aspartic (Asp) amino acid. The study was performed over the different range of reactants' concentration, temperature and pH. Reaction obeyed the order to be respective fractional and unity in [nin] and [Asp]. The values of several quantities, viz., critical micellar concentration (cmc), thermodynamic parameters, and binding parameters were calculated and described herewith. The experimental outcomes depict that the reaction is catalyzed, significantly, by twin headed gemini surfactants and follow the order at all concentration as: GS-4 > GS-5 > GS-6. In the rate constant (k ψ) vs. [GS] rate profiles, k ψ intensifies even at below cmc values of surfactants (region I), and previously observe practically unchanged behavior (region II). Finally, a fast changes in k ψ is detected (region III). Catalytic impact of twin headed GS achieved in this study is deduced by using a model called as micellar pseudo-phase in which rate constant depends on both the reactants. The numerous kinetic constants in twin headed geminis were evaluated and elaborated. An acceptable mechanism reliable with kinetics comprising the development of Ruhemanns' purple between nin and Asp has been proposed. [ABSTRACT FROM AUTHOR]

The interaction of amphiphilic antidepressant drug nortriptyline hydrochloride (NOT) with nonionic surfactant Triton X-100 (TX-100) was studied in this work using tensiometry in aqueous and in urea (500 mmol ∙ kg − 1 and 1000 mmol ∙ kg − 1 ) solutions at 303.15 K. Various models such as Clint, Rubingh, and Rosen etc. were employed to get the information regarding the nature of interaction between the compounds in bulk and at the interface. The CMC values of the mixed systems of NOT and TX-100 were found to be in between the CMC value of pure components, which suggest nonideal mixed system having attractive interactions in the absence and presence of urea. Enhancement in the surface charge of the micelles was obtained in the company of urea followed by halt of the micelles formation. Various physicochemical parameters, such as, micellar mole fraction ( X 1 Rub ) of TX-100, interaction parameters ( β σ , β m ) at monolayer air–water interface as well as in bulk solutions, thermodynamic parameters, activity coefficients ( f 1 m , f 2 m ), surface pressure at the CMC (π CMC ), for the TX-100 and NOT in the mixed micelles were determined as discussed in detail. Thermodynamic parameters (minimum energy of surface ( G min ), standard Gibbs energy of adsorption (Δ G ads ∘ ), free energy of micellization (Δ G ° m ), excess Gibbs energy of the mixed monolayer (Δ G ex σ ), excess Gibbs energy of the micelle formation (Δ G ex m ) and free energy of micellization (Δ G Maeda 0 ) (calculated by Maeda model)) and surface properties exposed that the addition of urea changes the relevant physicochemical properties which influence the process of micellization. [ABSTRACT FROM AUTHOR]

The desirable surface/bulk properties for specific applications of drug sodium salt of ibuprofen (IBF) and Triton X-100 (TX-100) can be achieved by adjusting mainly the composition of these systems. The interactions of anionic drug IBF with non-ionic surfactant TX-100 micelles have been investigated using tensiometry, fluorometry and 1 H NMR in aqueous as well in 250 mmol⋅kg −1 urea solutions. Different theoretical models like Clint, Rubingh, and Rosen, etc. were utilized to get information about the nature of interaction between these two in bulk and at the interface. These models disclose that the non-ideal behavior with attractive interaction in bulk and at the interface exists. The steady-state fluorescence quenching study was employed to evaluate micelle aggregation numbers ( N agg ), which signify the involvement of surfactant was forever higher compared to IBF. Stern–Volmer binding constants ( K sv ), micropolarity ( I 1 / I 3 ) and dielectric constant ( D exp ) of the mixtures are also obtained using fluorescence method. By the addition of urea raise in the surface charge of the micelles was observed followed by halt of the micellization of drug and surfactant as well as their mixture, therefore cmc values increases followed by decrease in aggregation number. The 1 H NMR resonance intensity variations were paralleled by upfield shifts in the resonance frequencies, due to an increased shielding of IBF happening from closeness of the non-ionic TX-100 surfactant. [ABSTRACT FROM AUTHOR]

The surface and micellization behavior of binary and ternary mixtures of cetylpyridinium chloride (CPC), sodium dodecyl sulfate (SDS) and polyethylene glycol hexadecyl ether (BRIJ-56) in different mole fractions have been studied in detail by surface tension measurement. The critical micelle concentration (CMC), activity coefficients, mutual interaction parameters, interfacial adsorption, minimum area per molecule, and energetic parameters for binary and ternary systems have been determined. Here we used the Clint, Rubingh and Rubingh–Holland models to analyze the results. [ABSTRACT FROM AUTHOR]

Herein, we have examined the interaction between promazine hydrochloride (PMZ) with bile salts (sodium cholate (NaC) and sodium deoxycholate (NaDC)) at different temperatures and compositions using conductometric method. The critical micelle concentration (cmc) value of pure PMZ and bile salts were also evaluated by tensiometric method. Thecmcvalues attained by the two methods are close to each other. Various physicochemical parameters likecmc, idealcmc(cmcid), degree of dissociation of counterion (g), micellar mole fractions of bile salt (,,), micellar mole fraction of bile salt in ideal state (), interaction parameter (βm), activity coefficients (f1,f2), standard Gibbs free energy (), enthalpy (), entropy of micellization (), and excess free energy of mixing (ΔGex) of the mixed micelles have been evaluated and discussed in detail using Clint's, Rubingh's, Motomura's, and Rodenas's models. NaDC is more efficient in decreasing thecmcof PMZ as compared to NaC because it binds strongly to PMZ ions and more decreases the head group area of drug. On the whole, this lesson might find application in the fundamental science of the physical chemistry of amphiphilic systems, as well as in the research of drug delivery system. [ABSTRACT FROM PUBLISHER]

The aim of the current study is the characterization of interaction of amphiphilic drug promazine hydrochloride (PMZ) with sodium dodecyl sulfate (SDS) in the absence and presence of inorganic salt and urea. Conductometric measurements were carried out to estimate the critical micelle concentrations ( CMC ) of drug and surfactant along with their mixtures. A gradual reduce in the surface charge of the micelles was recognized due to the adding of salt pursued by a speedy enlargement of the micelles hence the CMC value of amphiphiles decreases. In the presence of urea an increase in the surface charge of the micelles was obtained ensuing halt of the micelle formation. Different parameters like ideal critical micelle concentration ( CMC id ), degree of dissociation ( g ), thermodynamic parameters, micellar mole fraction of SDS, and interaction parameter have been evaluated using relevant formula given in the literature. All results pointed out attractive interactions in the mixtures of drug and surfactant and showed effective involvement of the surfactant (SDS) component in the mixture. The combined effect of non-covalent is accountable for the micellization phenomena. Excess free energy of micellization (Δ G ex ) values was also evaluated and discussed in detail. [ABSTRACT FROM AUTHOR]

The aggregation behavior of promazine hydrochloride (PMZ) and bile salt (sodium taurocholate (NaTC)) mixtures at various compositions and temperature in pure and mixed states were studied using conductometry technique in aqueous solutions. The values of experimental and ideal critical micelle concentration (cmc and cmcid) propose attractive interactions in PMZNaTC mixtures. By applying the regular solution theory (RST) various physicochemical parameter such as micellar mole fraction in the mixed (X1) and ideal (X1 id) state, interaction parameters (β), thermodynamic parameters of micellization as well as other related parameters have been evaluated and discussed in detail. The results show that the synergistic effect between drug and bile salt plays a crucial role in the redtd refuction of the overall cmc value in aqueous solution at various composition of NaTC. The thermodynamic parameters recommend the discharge of water from the hydrophobic part of the PMZ at higher temperatures. [ABSTRACT FROM AUTHOR]

Herein we have investigated the dealings between amphiphilic antidepressant drug amitriptyline hydrochloride (AMT) and gelatin interaction using different proposed techniques. AMT is used for the treatment of mental/mood problems such as depression. Gelatin interacts with this drug alike fashions to the interaction of polymers and surfactants i.e. , critical aggregation concentration ( cac ) and polymer saturation point ( psp ) were together achieved significantly. AMT and gelatin interaction starts due to the highly surface active complex formation as disclosed by decreasing of surface tension of gelatin solution by adding of AMT. It was uncovered from results that cac decreases on increasing the gelatin concentrations, whereas psp increases which is a sign of the attraction between AMT and gelatin. Thermodynamic parameters were also evaluated and discussed in detail. Fluorescence measurements were used to find the values of average aggregation numbers ( N agg ) and various other parameters like Stern–Volmer constant ( K sv ) and micropolarity. The nuclear magnetic resonance ( 1 H NMR) data suggested that AMT interacts with gelatin by the means of hydrophobic interaction. The 1 H NMR experiments explain that the extent of chemical shifts ( δ ) and line width ( lw ) increases with the increase in gelatin concentration. Secondary structure of gelatin was also examined via circular dichroism (CD) technique at different concentration of AMT. CD results confirmed that with increasing drug concentration the random coil portion of gelatin enhances. Field emission scanning electron microscope (FESEM) provided clear pictures of (drug + gelatin) interaction. [ABSTRACT FROM AUTHOR]

A new series of novel nanostructured poly (aniline-co-m-aminobenzoic acid) copolymer has been synthesized by chemical oxidative in-situ polymerization method using dodecylbenzene sulphonic acid (DBSA) as a soft template. The synthesized copolymers were characterized by Fourier Transform Infrared spectroscopy, Ultraviolet visible spectroscopy, X-ray diffraction and scanning electron microscopy. The infrared spectrum shows the characteristic peaks confirming the formation of the copolymer. The ultraviolet visible spectrum shows the π to π* transition and n to π* transition. X-ray diffraction pattern confirms the amorphous nature of the polymer. Scanning electron microscopic images show the new morphology of spherical granular sponge like structures in the range of 100 to 200 nm. Conducting properties of the copolymers were studied using four probe method. Copolymers doped with DBSA showed an increased conductivity in the order of 10-4 S/cm. These copolymers are found to be more soluble in polar solvents comparing to polyaniline homopolymer. [ABSTRACT FROM AUTHOR]

The effect of gemini (alkanediyl-α,ω-bis(dimethylcetylammonium bromide)) (16-s-16, s = 4, 5, 6) surfactants on the interaction of ninhydrin with chromium(III) complex of glycylphenylalanine ([Cr(III)-Gly-Phe]2+) has been investigated using UV-visible spectrophotometer at different temperatures. The order of reaction with respect to [Cr(III)-Gly-Phe]2+ is unity while it is fractional with respect to ninhydrin. Whereas, the values of rate constant (kΨ) increase and leveling-off regions, like conventional single chain cetyltrimethylammonium bromide (CTAB) surfactant, were observed with geminis, later produces a third region of increasing kΨ at higher gemini surfactant concentrations. This unusual third-region effect of the gemini micelles is assigned to changes in their micellar morphologies. The results obtained in micellar media were treated in terms of pseudo-phase model. The values of thermodynamic parameters (Ea, ΔH# and ΔS#) and binding constants (KA and KNin) have been evaluated. [ABSTRACT FROM AUTHOR]

Herein, we are reporting the interaction of biocompatible polymer polyvinylpyrrolidone (PVP), with gemini, pentamethylene-1,5-bis(hexadecyldimethylammonium bromide) (G5) and TX-114 surfactant mixture. Various thermodynamic parameters are evaluated with the help of regular solution theory (RST) and pseudo-phase separation model. By the addition of PVP, the critical aggregation concentration ( cac ) value of G5 as well as mixture decreases. A decrease in the cac value mainly credited to the interactions between the polymer and surfactant. The partial negative charged oxygen atoms, present in the amide group of PVP, were believed to be responsible for interaction with cationic head group of gemini surfactant. [ABSTRACT FROM AUTHOR]

Herein we report the interaction of amphiphilic drug clomipramine hydrochloride (CLP-a tricyclic antidepressant) with bovine serum albumin (BSA) studied by fluorescence, UV-vis, and circular dichroism (CD) spectroscopic techniques. Clomipramine hydrochloride is used to treat a variety of mental health problems. The quenching rate constant (kq) values, calculated according to the fluorescence data, decrease with increase in temperature indicating the static quenching procedure for the CLP-BSA interaction. The association binding constants (KA), evaluated at different conditions, and the thermodynamic parameters (free energy, enthalpy and entropy changes) indicate that the hydrophobic forces play a major role in the binding interaction of drug. The interaction of BSA with CLP was further confirmed by UV absorption spectra. Blue shift of position was detected due to the complex formation between the BSA-CLP. The molecular distance, r0, between donor (BSA) and acceptor (CLP) was estimated by fluorescence resonance energy transfer (FRET) whose value (4.47 nm) suggests high probability of static quenching interaction. The CD results prove the conformational changes in the BSA on binding with the drug. Thus, the results supply qualitative and quantitative understanding of the binding of BSA to CLP, which is important in understanding their effect as therapeutic agents. [ABSTRACT FROM AUTHOR]

In the present paper, reaction of zinc-glycylphenylalanine ([Zn(II)-Gly-Phe]+) with ninhydrin has been investigated in gemini (m- s-m type; m = 16, s = 4-6) surfactants at temperature (70 °C) and pH (5.0). Monitoring the appearance of product at 400 nm was used to follow the kinetics, spectrophotometrically. The order of the reaction with respect to [Zn(II)-Gly-Phe]+ was unity while with respect to [ninhydrin] was fractional. The reaction constants involved in the mechanism were obtained. In addition to the rate constant ( kΨ) increase and leveling-off regions are observed with the geminis, just like as seen with conventional surfactant hexadecyltrimethylammonium bromide (CTAB), the former produced a third region of increasing kΨ at higher concentrations. A close agreement between observed and calculated rate constants was found under varying experimental conditions. A suitable mechanism consistent with the experimental findings has been proposed. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In the present study, the influence of the hydrocarbon chain length of gemini surfactants on the process of micellization in mixed surfactant systems was investigated. Experiments were carried out with alkyldiyl-α, ω-bis(tetradecyldimethylammonium bromide) (m-4-m) dicationic gemini (m = 14, 16)/anionic sodium dodecylbenzene sulfonate (SDBS) mixed surfactant systems in different ratios. The critical micelle concentration (cmc) values of binary mixtures of surfactants were evaluated using surface tension measurements. Results showed that mixtures of the SDBS with gemini surfactants possessed significant deviations from ideal behavior (attractive interactions). The application of the regular solution theory (RST) to experimental data yielded the interaction parameter at mixed micelles (β) and air-water interface (βσ), indicating an attractive interaction and reflecting the synergistic behavior in both the systems. The experimental mole fraction (X1) was found to be lower than the ideal mole fraction (X1ideal), the mole fractions of SDBS for both systems, provided that mixed micelles were more occupied by SDBS. In addition, the micelle aggregation number (Nagg) increased with an increase in the length of the hydrophobic tail. The micropolarity and binding constant (Ksv) values of various combinations were determined from the ratio of intensity (I1/I3) of peaks of pyrene fluorescence emission spectrum and its quenching. [ABSTRACT FROM AUTHOR]