Encapsulation and Releasing of Calcein by Spontaneously Formed Zwitterionic/Anionic Vesicle without Separation

Formation of pH-responsive drug-delivery systems by electrospinning of vesicle-templated nanocapsule solutions

A novel nanofibrous membrane, which contains chitosan/sodium alginate nanocapsules constructed by vesicle systems, has been fabricated via an electrospinning process as a drug-delivery system.

Dual stimuli-responsive self-assembly transition in zwitterionic/anionic surfactant systems

Temperature and pH responsiveness is important for biological applications in protein reconstitution, gene delivery and controlled drug release. The temperature and pH dual responsive self-assembly transition, vesicle-to-micelle transitions (VMTs) and micelle-to-vesicle transitions (MVTs), in dodecyl sulfonatebetaine (DSB)/sodium bis(2-ethylhexyl) sulfosuccinate (AOT) aqueous solution are investigated. Various experimental techniques including cryogenic transmission electronic microscopy, UV-vis spectroscopy, fluorescence spectroscopy, conductivity, and zeta potential were employed to verify the transformation process. Encapsulation of calcein was further applied in this study. The results showed that the self-assembly transition in DSB/AOT aqueous solution is reversible and can be controlled by temperature and pH. It is anticipated that utilizing simple stimuli methods to realize unique self-assembly behaviour in dilute aqueous solution may offer new possibilities in cancer diagnosis and therapy.

Interaction between zwitterionic and anionic surfactants: spontaneous formation of zwitanionic vesicles

The physicochemical properties, such as critical micelle concentration (cmc), surface tension at cmc (γ(cmc)), and surface activity parameters of the mixtures of a new amino acid-based zwitterionic surfactant, N-(n-dodecyl-2-aminoethanoyl)-glycine (C(12)Gly) and an anionic surfactant, sodium dodecyl sulfate (SDS) at different molar fractions, X(1) (= [C(12)Gly]/([C(12)Gly] + [SDS])) of C(12)Gly were studied. A synergistic interaction was observed between the surfactants in mixtures of different X(1). The self-organization of the mixtures at different molar fractions, concentrations, and pH was investigated. Fluorescence depolarization studies in combination with dynamic light scattering, and transmission electron microscopic and confocal fluorescence microscopic images suggested the formation of bilayer vesicles in dilute solutions of SDS rich mixtures with X(1) ≤ 0.17 in the pH range 7.0 to 9.0. However, the electronic micrographs showed structures with fingerprint-like texture in moderately dilute to concentrated C(12)Gly/SDS mixture at X(1) = 0.50. The vesicles were observed to transform into small micelles upon lowering the solution pH and upon increase of total surfactant concentration in mixtures with X(1) ≤ 0.17. However, decrease of SDS content transformed vesicles into wormlike micelles. The structural transitions were correlated with bulk viscosity of the binary mixtures.