National Institute Of Materials Physics - Romania

In this paper we present the preparation and biological tests of iron oxide nanoparticles coated with dextrin. Iron oxide was also prepared by co-precipitation. The samples were characterized by transmission electron microscopy (TEM) and 14 scanning electron microscopy (SEM). Biocompatibility test of the iron oxide nanoparticles coated with dextrin substrate has been done using primary osteoblast cell line. After osteoblast culture achievement, the cells were treated with trypsin 0.05% and splitted in 35/35 mm Petri dish. The influence in vitro was assessed using primary osteoblast cell line and various techniques to observe cell-particles interactions. The results of these analyses are presented in this work.

Nickel nano- and micro- tubes were prepared by electroless deposition in ion track template membranes. By choosing the appropriate etching conditions membranes with cylindrical or conical pores were obtained allowing the preparation of cylindrical or conical tubules. The activation of the membranes was a two step process. The bath used for deposition was an acidic one. Typically for acidic bath deposition, by energy dispersive X ray analysis, a phosphorous content of up to 10 % was found in the deposit.

Creatinine thin films were synthesised by matrix assisted pulsed laser deposition (PLD) techniques for enzyme-based biosensor applications. An UV KrF* (lambda = 248 nm, tau similar to 10 ns) excimer laser source was used for the irradiation of the targets at incident fluence values in the 0.3-0.5 J/cm(2) range. For the matrix assisted PLD the targets consisted on a frozen composite obtained by dissolving the biomaterials in distilled water. The surface morphology, chemical composition and structure of the obtained biomaterial thin films were investigated by scanning electron microscopy, Fourier transform infrared spectroscopy, and electron dispersive X-ray spectroscopy as a function of the target preparation procedure and incident laser fluence.

Photoluminescence properties of Er3+-doped calcium niobium gallium garnet (CNGG) disordered crystals have been studied in the range of 200-2000 nm at 10-290 K. In addition to emission bands due to Er3+, a broad emission band is observed at 470 nm. From the emission spectra that were obtained by various excitations, level assignment has been established for the emission bands. Different temperature dependences are observed between the emission bands at 522 and 543 nm. This is explained using non-radiative phonon relaxation between the H-2(11/2) and S-4(3/2) states. Besides the 1535 nm Er3+ emission band, near infrared emission bands are observed at 860 and 1240 nm, which are attributed to the transitions from the S-4(3/2) state to the (4)vertical bar(13/2) and vertical bar 4(11/2) states, respectively.

Photoluminescence (PL) properties of the composites based on zinc oxide (ZnO) and single-walled carbon nanotubes (SWNTs) prepared by hydrothermal synthesis are studied in this paper. The emission and excitation spectra of nanometric ZnO powder are dramatically influenced by the adsorption of different molecules coming from the environment. Therefore, a special attention is given to reveal the influences of adsorption/de-sorption process on photoluminescence properties of zinc oxide nanoparticles. A quenching effect of the intrinsic PL is observed regularly when the ZnO is synthesized in the presence of SWNTs, i.e. when a ZnO/SWNTs composite is formed. A distinct feature of the ZnO/SWNTs composite, is an emission band with a maximum at 405-450 nm.

Intercalated PbI2 compounds were prepared by exposing crystalline films and crystalline powders of lead iodide to pyridine or iodine vapor at room temperature. Correlated studies of optical absorption, Raman scattering and low temperature photoluminescence (PL) reveal different properties in comparison with those of pure crystalline PbI2 powder. Depending of the nature of intercalated molecules (organic or inorganic) the basic semiconducting properties of PbI2 are dramatically modified. The main signature of iodine intercalated PbI2 consists in a luminescence band peaking at 2.24 eV appearing at 77 K under 350 nm excitation light. In the case of pyridine intercalated PbI2 a new intense band at about 3.3 eV in the absorption spectrum is observed. The the PL spectra of pyridine intercalated PbI2 at 77 K change substantially when the excitation wavelength. The Raman spectra confirm the presence of pyridine between the PbI2 layers.

This work reports on recently investigated structural and magnetic properties of three FexOy-SiO2 nanocomposites prepared by the alkoxide route of the sol-gel method. Depending on the presence or absence of catalyst and on its nature (acidic or basic), important differences among the samples have been observed from the point of view of their structure and properties. (c) 2007 Elsevier B.V. All rights reserved.

The iron oxide nanoparticles and iron oxide nanoparticles coated with dextrin have been synthesized using aqueous solution of ferric and ferrous ions and mixtures of dextrin with sodium salt. The size of the iron-oxide nanoparticles are controlled by the concentration of sodium salt in the medium. An average size of iron oxide and iron oxide coated with dextrin was found by transmission electron microscopie (TEM). The iron oxide nanoparticles are nearly spherical with an average diameter of about 8.0 +/- 1 nm. The iron oxide nanoparticles coated with dextrin appear to cluster-like aggregates. The average diameter of these nanoparticles is about 6 1 nm. The attachment of the dextrin on the particle surface was confirmed by FTIR spectroscopy and scanning electron microscopy (SEM). Osteoblasts used to determine the cell proliferation, viability and citotoxicity interaction with iron oxide nanoparticles coated with dextrin has been obtained from the upper part of the patient's femur.

Preparation of ZnO in different nano-morphological forms became a hot topic during the last few years. This tendency was motivated by the wide field of potential applications ranging from optics to electronics and spintronics. In the present work, we deal with the preparation of ZnO nanowires and nanostructured thin films using electrochemical deposition. ZnO nanowires were grown using the template approach, namely by replicating the nanopores of polycarbonate ion track membranes. The method yields uniform arrays of nanowires with the morphology controlled by the shape and size of the templates pores. Adding polyvinylpyrolidone as an additive in the growth bath became a necessity due to the fact that polycarbonate ion track membranes are usually hydrophobic and thus filling of the nanopores with the growth electrolyte is rather difficult. In order to better understand the influence of the additive on the electrochemical deposition of such nanostructures, similar experiments were performed for the deposition of ZnO thin films. Scanning electron microscopy, X-ray diffraction and optical spectroscopy measurements were performed for characterization of the deposited structures. Copyright (c) 2008 John Wiley & Sons, Ltd.

PbSe nanowires were prepared using the template method. Polycarbonate ion track membranes with pore sizes ranging between 50 nm and 1.5 mu m were used as templates. The deposition of PbSe in the pores of the template was performed electrochemically. The influence of the deposition potential and membrane porosity on the morphology and composition of the prepared nanowires was studied. The composition of the wires has been determined by EDX measurements for different potentials. Scanning electron microscopy revealed the morphology of the deposited nanowires. X ray diffraction has been used for structural measurements.