Abstract
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 H-1 NMR techniques in aqueous and in the occurrence of 250 mmol kg(-1) urea (NH2CONH2). 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 (beta(m)/beta(sigma)), maximum surface excess concentration (Gamma(max)), Gibb's free energy of micellization (Delta G(m)), Gibb's free energy of adsorption (Delta G(ads)), excess free energy of aggregation/interface (Delta G(ex)(m)/Delta G(ex)(sigma)) 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 beta(m)/beta(sigma) 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 Delta G(m) and Delta 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 (Nagg) 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 H-1 NMR spectroscopic method which recommended that drug and surfactant interact via hydrophobic interaction in absence and occurrence of NH2CONH2.