The Cytotoxic Effects of Betulin-Conjugated Gold Nanoparticles as Stable Formulations in Normal and Melanoma Cells

Gold nanoparticles are currently investigated as theranostics tools in cancer therapy due to their proper biocompatibility and increased efficacy related to the ease to customize the surface properties and to conjugate other molecules. Betulin, [lup-20(29)-ene-3β, 28-diol], is a pentacyclic triterpene that has raised scientific interest due to its antiproliferative effect on several cancer types. Herein we described the synthesis of surface modified betulin-conjugated gold nanoparticles using a slightly modified Turkevich method. Transmission electron microscopy (TEM) imaging, dynamic light scattering (DLS), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) were used for the characterization of obtained gold nanoparticles. Cytotoxic activity and apoptosis assessment were carried out using the MTT and Annexin V/PI apoptosis assays. The results showed that betulin coated gold nanoparticles presented a dose-dependent cytotoxic effect and induced apoptosis in all tested cell lines

Tight-binding normal mode analysis of suspended single-wall carbon nanotubes

We present a detailed normal mode analysis of suspended single-wall carbon nanotubes based on a non-orthogonal tight-binding formalism and a new methodology for classifying vibrational modes, using geometry-adapted merit functions. The fundamental modes are in good agreement with experiments and previous calculations. The analysis of the high-order vibrations evidences interesting non-classical features, while the sensitivity of the normal modes to the nanotube geometry provides new insights useful for practical realizations of mass resonators

Analysis of a history-dependent frictional contact problem

International audienceWe consider a mathematical model which describes the quasistatic contact between a viscoelastic body and a foundation. The material’s behaviour is modelled with a constitutive law with long memory. The contact is frictional and is modelled with normal compliance and memory term, associated to the Coulomb’s law of dry friction. We present the classical formulation of the problem, list the assumptions on the data and derive a variational formulation of the model. Then we prove the unique weak solvability of the problem. The proof is based on arguments of history-dependent variational inequalities. We also study the dependence of the weak solution with respect to the data and prove a convergence result

Iron(II)-Catalyzed Activation of Si–N and Si–O Bonds Using Hydroboranes

International audienceWe report the activation and functionalization of Si–N bonds with pinacol borane catalyzed by a three-coordinate iron(II) β-diketiminate complex. The reactions proceed via mild silazanes to yield useful hydrosilanes aminoboranes. reaction is studied kinetic analysis, along detailed investigation decomposition pathways using catecholborane as an analogue used in catalysis. have extended methodology develop polycarbosilazane depolymerization strategy, which generates hydrosilane quantitatively complete conversion Bpin-protected diamine. analogous Si–O bond cleavage can also be achieved heating, silyl ether starting materials generate alkoxyborane products. Depolymerization poly(silyl ether)s our strategy successfully converts polymer 90% alcohols

Two history-dependent contact problems

International audienc