Molecular Mechanism for Formation of Polyaniline Lamella from a Lyotropic Liquid Crystal: An NMR Study

Effect of sodium lauryl sulfate-mediated gelation on the suppressed dissolution of crystalline lurasidone hydrochloride and a strategy to mitigate the gelation

In dissolution test, the surfactant sodium lauryl sulfate (SLS) is usually added to increase the dissolution of insoluble drugs and achieve the sink condition. However, the current study found that 0.1 % SLS would significantly decrease the dissolution of crystalline lurasidone hydrochloride (LH, a BCS Ⅱ drug). The aim of this study was to clarify the mechanism of this unexpected phenomenon and explore a strategy for mitigating the negative effect of SLS on the dissolution of LH. Sample characterizations (such as PLM, DSC, PXRD, IR and NMR) confirmed that the insoluble single-phase amorphous LH-SLS complex (with a single T_g at 35.2 °C) formed during dissolution in 0.1 % SLS aqueous solution via electrostatic interaction, tetrel bond interaction, and hydrophobic effect. Due to the plasticization effect of water, the transition of amorphous LH-SLS from its glassy state to viscous supercooled liquid state led to the gel formation, and suppressd the dissolution of LH. Meanwhile, the solubility curve of LH in SLS aqueous solution at various concentrations exhibited an unusual V-shaped feature, with the CMC value of SLS serving as the inflection point, since the gel degree was attenuated due to the micelle solubilization of SLS. Additionally, an innovative strategy was developed to alleviate the inhibiting effect of SLS on LH dissolution based on the potential competitive interactions. This study not only enriches the internal mechanism of surfactant-inhibited drug dissolution but also informs an effective strategy to mitigate the gelation.

Highly oriented lamellar polyaniline films via electrochemical polymerization and post-growth annealing

Electrochemical polymerization on ITO electrodes followed by post-growth annealing produces highly oriented lamellar polyaniline films.

Effect of Surfactant on Growth of ZnO Nanodumbbells and Their Characterization

We report the controlled synthesis of dumbbell shaped ZnO micro/nanostructures using anionic surfactant sodium dodecyl sulphate (SDS) by simple one-step hydrothermal method. The morphology changes of ZnO were characterized by using scanning electron microscopy, X-ray diffraction, and energy dispersive spectroscopy. It is found that the size of the dumbbell increased with increase in concentration of SDS. Systematic growth mechanism with increase of concentration of SDS polymer is studied. Our results will help in the growing face selective ZnO for many functional applications.