by Keyword: SAXS

Ramos, E., Pardo, W. A., Mir, M., Samitier, J., (2017). Dependence of carbon nanotubes dispersion kinetics on surfactants Nanotechnology 28, (13), 135702

Carbon nanotubes (CNTs) have been the subject of many studies due to their unique structure and desirable properties. However, the ability to solubilize and separate single CNTs from the bundles they form is still a challenge that needs to be overcome in order to extend their applications in the field of Nanotechnology. Covalent interactions are designed to modify CNTs surface and so prevent agglomeration. Though, this method alters the structures and intrinsic properties of CNTs. In the present work, noncovalent approaches to functionalize and solubilize CNTs are studied in detail. A dispersion kinetic study was performed to characterize the ability of different type of surfactants (non-ionic, anionic, cationic and biopolymer) to unzip CNT bundles. The dispersion kinetic study performed depicts the distinct CNTs bundles unzipping behavior of the different type of surfactants and the results elucidate specific wavelengths in relation with the degree of CNT clustering, which provides new tools for a deeper understanding and characterization of CNTs. Small angle x-ray scattering and transmission electron microscopy results are in agreement with UV-vis-NIR observations, revealing perfectly monodispersed CNTs for the biopolymer and cationic surfactant.

JTD Keywords: Dispersion, DNA, Single-walled carbon nanotubes (SWCNTs), Small angle x-ray scattering (SAXS), Sodium dodecyl sulfate (SDS), Surfactant, Triton X-100

Manca, M. L., Castangia, I., Matricardi, P., Lampis, S., Fernàndez-Busquets, X., Fadda, A. M., Manconi, M., (2014). Molecular arrangements and interconnected bilayer formation induced by alcohol or polyalcohol in phospholipid vesicles Colloids and Surfaces B: Biointerfaces 117, 360-367

A self-assembled hybrid phospholipid vesicular system containing various penetration enhancers - ethanol, Transcutol and propylenglycol - was prepared and characterized. The effects of the different alcohol or polyalcohols structure and their concentration on the features of the assembled vesicles were evaluated using a combination of different techniques, including cryo-transmission electron microscopy, laser light scattering, differential scanning calorimetry, small- and wide-angle X-ray scattering and rheological analysis. These techniques allow explaining the structural rearrangements of the bilayer assembly due to the alcohol or polyalcohol addition. X-ray scattering studies showed that such addition at the highest concentration (20%) allowed structure modification to oligolamellar vesicles and a bilayer transition to interdigitated phase. Rheological studies confirmed the importance of alcohol or polyalcohol in the structuring dispersions probably due to a partial tilting of phosphatidylcholine acyl chains forming interdigitated and interconnected bilayer vesicles.

JTD Keywords: (Poly)alcohols, Cryo-TEM, DSC, Liposomes, Penetration Enhancer containing Vesicle (PEVs), Rheology, SAXS