Synthesis of CdS and CdSe nanocrystallites using a novel single-molecule precursors approach

The synthesis of CdS and CdSe nanocrystallites using the thermolysis of several dithioor diselenocarbamato complexes of cadmium in trioctylphosphine oxide (TOPO) is reported. The nanodispersed materials obtained show quantum size effects in their optical spectra and exhibit near band-edge luminescence. The influence of experimental parameters on the properties of the nanocrystallites is discussed. HRTEM images of these materials show well-defined, crystalline nanosized particles. Standard size fractionation procedures can be performed in order to narrow the size dispersion of the samples. The TOPO-capped CdS and CdSe nanocrystallites and simple organic bridging ligands, such as 2,2¢-bipyrimidine, are used as the starting materials for the preparation of novel nanocomposites. The optical properties shown by these new nanocomposites are compared with those of the starting nanodispersed materials

Evolution of the electronic structure with size in II-VI semiconductor nanocrystals

In order to provide a quantitatively accurate description of the band gap variation with sizes in various II-VI semiconductor nanocrystals, we make use of the recently reported tight-binding parametrization of the corresponding bulk systems. Using the same tight-binding scheme and parameters, we calculate the electronic structure of II-VI nanocrystals in real space with sizes ranging between 5 and 80 {\AA} in diameter. A comparison with available experimental results from the literature shows an excellent agreement over the entire range of sizes.Comment: 17 pages, 4 figures, accepted in Phys. Rev.

Conformational control of integrin subtype selectivity in isoDGR peptide motifs: A biological switch

Thumbnail image of graphical abstract The rearrangement of asparagine to isoaspartate (isoD) is responsible for the deactivation of many functional proteins. However, the isoDGR motif, which is optimally presented as a conformationally controlled cyclic pentapeptide, binds selectively to a5ß1 integrin (see the docking model) with an affinity comparable to that of the peptidic antitumor agent CilengitidePeer ReviewedPostprint (published version

Fabrication of Massive Sheets of Single Layer Patterned Arrays Using Lipid Directed Reengineered Phi29 Motor Dodecamer

The bottom-up assembly of patterned arrays is an exciting and important area in current nanotechnology. Arrays can be engineered to serve as components in chips for a virtually inexhaustible list of applications ranging from disease diagnosis to ultra-high-density data storage. Phi29 motor dodecamer has been reported to form elegant multilayer tetragonal arrays. However, multilayer protein arrays are of limited use for nanotechnological applications which demand nanoreplica or coating technologies. The ability to produce a single layer array of biological structures with high replication fidelity represents a significant advance in the area of nanomimetics. In this paper, we report on the assembly of single layer sheets of reengineered phi29 motor dodecamer. A thin lipid monolayer was used to direct the assembly of massive sheets of single layer patterned arrays of the reengineered motor dodecamer. Uniform, clean and highly ordered arrays were constructed as shown by both transmission electron microscopy and atomic force microscopy imaging

An α5β1 integrin inhibitor attenuates glioma growth

Integrins are heterodimeric transmembrane proteins, which mediate cell-cell and cell-extracellular matrix (ECM) interaction. We show, that an inhibitor of alpha5 beta1 integrin ({alpha}5{beta}1), JSM6427, attenuated glioma growth and decreased the density of microglia at the tumor border. 21 days after glioma cell injection into an experimental mouse model, the tumor volume was significantly smaller after treating animals for 14 days with JSM6427 as compared to controls. We could demonstrate the expression of integrin {alpha}5 beta1 on both microglia and glioma cells using flow cytometry. In a slice culture we could compare glioma growth in the presence and absence of microglia. Slices injected with glioma cells were treated with the integrin inhibitor JSM6427 and showed a significant reduction in tumor size as compared to control. Depleting microglial cells from the slice culture by treatment with clodronate liposomes abrogated the effect of JSM6427 on glioma invasion indicating that the presence of microglia is required. We show further, that microglial migration, and proliferation was attenuated dose-dependently by JSM6427

Influence of growth temperature on phase and intermixing in Ni2Ni_{2}MnIn Heusler films on InAs(001)

This paper reports on the influence of deposition temperature on structure and morphology of uncapped Ni2MnIn Heusler films grown by molecular beam epitaxy on InAs(0 0 1). Deposition temperatures between 80 and 360 °C and layer thicknesses between 20 and 100 nm have been used. Our studies reveal that during growth beyond 80 °C an intermixing layer arises at the Heusler/substrate interface that is formed by diffusion of arsenic from the substrate. The intermixing process, which is found to take place via interstitial sites, becomes increasingly severe with increasing growth temperature. Furthermore, we find that the films grown at 80 °C are polycrystalline with crystallites in the B2 phase. At 250 °C the films are found to be single-crystalline and pseudomorphically strained in the B2 phase. The desired L21 phase and single-crystalline Heusler films are observed at a growth temperature of 300 °C. Interestingly, Heusler films in L21 phase are found to have a (1 1 0) surface orientation in contrast to the InAs(0 0 1) substrate crystal. At temperatures higher than 300 °C, strong intermixing and a morphological degradation of the L21 Heusler films is observe