Two-photon excitation of curcuminoid borondifluoride nanoparticles in water results in rather efficient luminescence in the near infrared region due to a high two-photon cross-section.

This article describes a series of nine complexes of boron difluoride with 2'-hydroxychacone derivatives. These dyes were synthesized very simply and exhibited intense NIR emission in the solid state. Complexation with boron was shown to impart very strong donor-acceptor character into the excited state of these dyes, which further shifted their emission towards the NIR region (up to 855 nm for dye 5 b, which contained the strongly donating triphenylamine group). Strikingly, these optical features were obtained for crystalline solids, which are characterized by high molecular order and tight packing, two features that are conventionally believed to be detrimental to luminescence in organic crystals. Remarkably, the emission of light from the π-stacked molecules did not occur at the expense of the emission quantum yield. Indeed, in the case of pyrene-containing dye 4, for example, a fluorescence quantum yield of about 15 % with a fluorescence emission maximum at 755 nm were obtained in the solid state. Moreover, dye 3 a and acetonaphthone-based compounds 1 b, 2 b, and 3 b showed no evidence of degradation as solutions in CH(2) Cl(2) that contained EtOH. In particular, solutions of brightly fluorescent compound 3 a (brightness: ε×Φ(f) =45,000 M(-1) cm(-1)) could be stored for long periods without any detectable changes in its optical properties. All together, these new dyes possess a set of very interesting properties that make them promising solid-state NIR fluorophores for applications in materials science.

International audienceTitanate nanotubes (Ti-Nts) have proved to be a potential candidate for drug delivery due to their large surface change and higher cellular uptake as a direct consequence of their tubular shape. Ti-Nts were assessed for their safety, their kinetics of cellular uptake on U87-MG cell line and for genistein loading efficiency. No cytotoxic effect was observed under higher empty Ti-Nts concentrations up to 100 mu g mL(-1). The multiwalled tubular morphology was found to be an important parameter promoting high drug loading. The Ti-Nts could achieve higher genistein drug-loading content (25.2%) and entrapment efficiency (51.2%) leading to a controlled drug release as well as a higher cellular uptake of genistein-loaded- Ti-Nts which induces higher cytotoxicity and significant anti-migratory effect on U87-MG human glioblastoma astrocytoma, promising efficient antitumor activity

The true chemical nature and physical state of the catalyst particles in Catalytic Chemical Vapor Deposition (CCVD) synthesis of carbon nanotubes are the subject of intense discussions, as it is one of the keys to understand their growth mechanisms. The CCVD method considered in this article involves pyrolysis of mixed liquid aerosols and leads to the synthesis of large carpets of multiwalled nanotubes (MWNTs) partially filled with iron-based materials. The experimental approach consists in studying the influence of the cooling procedure applied at the end of the synthesis. Both slow standard cooling or quenching were performed, and the structure and chemical state of the iron-based particles were compared through complementary local and global investigations involving X-ray diffraction, electron microscopy, electron diffraction, as well as electron energy loss spectroscopy. We clearly demonstrate that iron-based catalyst particles are carbon-rich and oxygen-free in quenched samples, and that they oxidize during the slow cooling step. It is inferred that they are very probably molten supersaturated carbon-metal particles during the NT growth

X-ray fluorescence microscopy (microXRF) is applied for the first time to study macrophages exposed to unpurified and purified single-walled (SW) and multiwalled (MW) carbon nanotubes (CNT). Investigating chemical elemental distributions allows one to (i) image nanotube localization within a cell and (ii) detect chemical modification of the cell after CNT internalization. An excess of calcium is detected for cells exposed to unpurified SWCNT and MWCNT and related toxicological assays are discussed.

of the spin injection. To avoid these two phenomena we investigate the growth of Mn 5 Ge 3 and C-doped Mn 5 Ge 3 films on Ge(111) substrates by molecular beam epitaxy at room-temperature. The reactive deposition epitaxy method is used to deposit these films. Reflection high energy electron diffraction, X-ray diffraction analysis, transmission electron microscopy and atomic force microscopy indicate that the crystalline quality is very high. Magnetic characterizations by superconducting quantum interference device and ferromagnetic resonance reinforce the structural analysis results on the thin films quality.

The 2C protein, which is an essential ATPase and one of the most conserved proteins across the Picornaviridae family, is an emerging antiviral target for which structural and functional characterization remain elusive. Based on a distant relationship to helicases of small DNA viruses, piconavirus 2C proteins have been predicted to unwind double-stranded RNAs. Here, a terminally extended variant of the 2C protein from echovirus 30 has been studied by means of enzymatic activity assays, transmission electron microscopy, atomic force microscopy and dynamic light scattering. The transmission electron-microscopy technique showed the existence of ring-shaped particles with ∼12 nm external diameter. Image analysis revealed that these particles were hexameric and resembled those formed by superfamily 3 DNA virus helicases.

For the first time, using an extrusion process, macroscopic composite poly-vinyl alcohol(PVA)/poly-aniline (PANI)-V2O5 fibers have been generated. Besides the extrusion process itself, this is certainly the first redox reaction addressed while performing an extrusion shaping process. The as-synthesized fibers have been characterized at different length scales, revealing at the mesoscale a 30° preferential orientation of the nanoribbons subunits toward the macroscopic fiber main axis. At the microscopic length scale, despite a semiamorphous nature, electron spin resonance (ESR) spectroscopy has been employed to reveal partial reduction of V5+ species to V4+ ones, where the paramagnetic species local environment has been found to be close to hydrated vanadium oxide xerogels. Concerning the organic counterpart, the aniline is oxidized into poly aniline when considering both the fibers characterization through ESR and Fourier transformed infrared (FTIR) spectroscopy and the well-known strongly oxidizing character of V5+ species toward aniline. These new PVA/PANI-V2O5 fibers are cycling when sensing alcoholic vapors while offering a good selectivity. The addressed sensitivity allows sensing 5 ppm of ethanol within 3−5 s at 42 °C. Beyond, the as-synthesized PVA/PANI-V2O5 macroscopic fibers possess a toughness of 12 J g−1, a value that has been increased by more than 120 times when compared with nanoporous inorganic fibers.