Liquid exfoliation of mechanochemically nanostructured tungsten disulfide to a graphene-like state.

The possibility of the efficient preparation of graphene-like 1H-WS2 by the primary solventless nanostructuration of bulk 2H-WS2 by means of its mechanochemical treatment in the presence of a chemically inert agent (NaCl) and the subsequent liquid exfoliation of the nanostructured 2H-WS2 in an organic solvent is shown for the first time. The shear stresses generated during the grinding of the WS2/NaCl mixture caused the formation of WS2 particles with a reduced number of layers, while the stresses normal to their surface led to their cracking and a significant reduction in lateral size. The graphene-like morphology of the 1H-WS2 nanoparticles in the prepared dispersions is confirmed by atomic force microscopy and Raman spectroscopy. The semiconducting character of 1Н-WS2 is supported by electron absorption and x-ray photoelectron spectroscopy data.

Optical Properties of Pyrolytic Carbon Films Versus Graphite and Graphene.

We report a comparative study of optical properties of 5-20 nm thick pyrolytic carbon (PyC) films, graphite, and graphene. The complex dielectric permittivity of PyC is obtained by measuring polarization-sensitive reflectance and transmittance spectra of the PyC films deposited on silica substrate. The Lorentz-Drude model describes well the general features of the optical properties of PyC from 360 to 1100 nm. By comparing the obtained results with literature data for graphene and highly ordered pyrolytic graphite, we found that in the visible spectral range, the effective dielectric permittivity of the ultrathin PyC films are comparable with those of graphite and graphene.

Study of anti-fibrillogenic activity of iron(II) clathrochelates.

The macrocyclic compounds mono- and bis-iron(II) clathrochelates were firstly studied as potential anti-fibrillogenic agents using fluorescent inhibitory assay, atomic force microscopy and flow cytometry. It is shown that presence of the clathrochelates leads to the change in kinetics of insulin fibrillization reaction and reduces the amount of formed fibrils (up to 70%). The nature of ribbed substituent could determine the activity of clathrochelates-the higher inhibitory effect is observed for compounds containing carboxybenzenesulfide groups, while the inhibitory properties only slightly depend on the size of complex species. The mono- and bis-clathrochelate derivatives of meta-mercaptobenzoic acid have close values of IC50 namely 16 ± 2 and 24 ± 5 µM, respectively. The presence of clathrochelates decreases the fibril diameter from 5-12 nm for free insulin fibrils to 3-8 nm for these formed in the clathrochelate presence, it also prevents the lateral aggregation of mature fibrils and formation of superfibrillar clusters. However the addition of clathrochelate results in more heterogeneous (both by size and structure) insulin aggregates population as compared to the free insulin. This way, cage complexes-iron(II) clathrochelates are proposed as efficient agents able to suppress the protein aggregation processes.