Formation and characterization of natural polysaccharide hollow nanocapsules via template layer-by-layer self-assembly

With natural polysaccharides carrageenan (Car) and chitosan (Cs) as the polyanion and polycation, respectively, multilayer hollow nanocapsules have been fabricated via sequential layer-by-layer (LbL) electrostatic self-assembly from the sacrificed templates nanospheres (SiO(2)-NH(2)). The LbL assembly process with the polysaccharides on SiO(2)-NH(2) core was followed by ζ-potential and size analysis. The fabrication of (Car/Cs)(x) nanocapsules and the removing of the SiO(2)-NH(2) core templates were confirmed by TGA and EDS analysis. The morphology of SiO(2)(Car/Cs)(x) nanospheres and (Car/Cs)(x) nanocapsules were observed by TEM analysis. The size analysis of (Car/Cs)(x) nanocapsules indicated that the cyst wall thickness and cavity volume of the nanocapsules are pH and ionic strength dual responsive. Due to the biocompatibility of the natural polysaccharides carrageenan and chitosan and the responsiveness of nanocapsules to pH and ionic strength, the (Car/Cs)(x) multilayer nanocapsules are expected to be used as nanoreactors or nanocontainers to control the synthesis, encapsulation, and releasing behaviors of bioactive molecules.

Thin water layers on CaCO3 particles dispersed in oil with added salts

We report an investigation of the presence of thin water layers on calcium carbonate particles dispersed in cyclohexane using small-angle neutron scattering. We identify an adsorbed water layer and measure the thickness using contrast variation to optimize the sensitivity of the scattering to the water. We also report the variation in thickness of these water layers in the presence of salt solutions with the variation of salt concentration and valency. We conclude that thin water layers can be observed using SANS; however, the layers are thin and correspond to essentially the hydration of the particle surfaces.

CaCO(3) nanoparticle synthesis by carbonation of lime solution in microemulsion systems

Various aspects of nanoparticle precipitation in gas-reverse micellar systems have been studied. The experimental system chosen for investigation deals with the precipitation of CaCO(3) nanoparticles. The effect of operating variables, such as water-to-surfactant molar ratio, different continuous phases, surfactant concentration and stirring speed, have been investigated experimentally. The results indicate that using low concentrations of Ca(OH)(2) particles outside the micelles, low surfactant concentrations, low stirring speeds and water-to-surfactant molar ratios lead to the formation of smaller nanoparticles in gas-reverse micellar systems.