Unraveling the solubilization and cytotoxicity study of poorly water-soluble anti-inflammatory drug in aqueous Gemini surfactants solution with physicochemical characterization and simulation study.

This work investigates the use of quaternary ammonium based Gemini surfactants (GS) to examine the solubilization and stabilization of a poorly water soluble anti-inflammatory drug Diclofenac (Df). Here we demonstrate the effect of pH on the suspension profile of Df release where it exhibits maximum solubility and absorbance at pH = 10. Interaction process of such cationic GS with Df have been systematically characterized using tensiometry and UV-vis spectroscopy techniques from pre-micellar to post-micellar regions. The spectral results revealed that all the individual GS bind on Df electrostatically resulting in GS + Df complexation. For all the three GS examined, the critical micelle concentration (CMC) was found to decrease in presence of Df following the order: 12-2-12 > 12-2-16 > 16-2-16 which inferred that 12-2-12 can effectively suppress Df degradation at very low concentration. In comparison to 12-2-12, 12-2-16 and 16-2-16 exhibited weaker interaction with Df which limits the stability/solubility of Df in their respective micelles. The aggregation behavior of Df with various GS was investigated by dynamic light scattering (DLS) method. The structural orientation of GS and Df was elucidated by molecular simulation study using Gauss View 5.0.9. The influence of the 12-2-12 in presence of Df on the cervical cell morphology has been undertaken to understand the cytotoxic effect using MTT assay.

Synergism and aggregation behaviour in an aqueous binary mixture of cationic-zwitterionic surfactants: physico-chemical characterization with molecular simulation approach.

Aqueous interactions between a cationic surfactant benzyl dimethylhexadecylammonium chloride (BDHAC) and alkyldimethylammoniopropane sulfonates (CnDAPS) based three zwitterionic surfactants n = 10, 12, and 14 (abbreviated as C10DAPS, C12DAPS and C14DAPS, respectively) were studied using tensiometry, and fluorescence spectrophotometry techniques. The critical micelle concentration degree of synergism and various other parameters such as interaction parameter (ß), activity coefficients (fm) and interfacial parameters such as surface pressure (πCMC), packing parameter (P), surface excess concentration (Γmax), surface tension at CMC (γCMC), and minimum area per molecule (Amin) were evaluated using the Regular Solution Theory (RST) of mixed systems. The results indicate a strong dependency on the mixed system and their composition. For the quantitative prediction, the molecular architecture of the surfactants in mixed systems and their synergistic interactions were investigated by computational simulation using Spartan'14 V1.1.8. The structural optimization results obtained were found to be in good agreement with the estimations made using RST. The reduction in surface tension indicates a certain efficiency in mixed micelle formation owing to electrostatic attraction between the cationic and zwitterionic surfactants. In addition, the binary surfactant systems evaluated by Maeda's approach infer the mixed micelles are thermodynamically stable. The aggregation number (Nagg) appeared to be larger at the composition point where the efficiency of mixed micelle formation is greatest. The strength of the interaction between BDHAC and CnDAPS followed the order: C14DAPS > C12DAPS > C10DAPS indicating a greater synergism at 0.25 molar ratio of zwitterionic surfactants to cationic surfactants in the aqueous solution at 303.15 K.