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SETNanoMetro, a European Seventh Framework project, seeks to develop standard synthetic routes and metrological characterisation methods for the development and production of TiO2 nanoparticles and nano-sized coatings with highly-defined, homogeneous and reproducible characteristics. These materials are being tested for their potential in selected technological applications, including as biomaterials, specifically as coatings on dental or orthopaedic metallic prostheses. This study aimed to assess how variations in nano-scale morphology and phase composition of TiO2 coatings affect their biocompatibility in vitro.
Pulsed DC magnetron sputtering was used to deposit a layer of Ti metal followed by a layer of TiO¬2 on standard glass microscope slides. The substrate bias voltage was varied during deposition to control the morphology and phase composition of the TiO2 layers. In order of increasing substrate bias voltage, the phase compositions of the TiO2 layers were: predominantly anatase, mixed anatase/rutile, and predominantly rutile, as confirmed by XRD. Examination of the coating cross-sections by SEM revealed feather-like columnar structures in the thin (950 nm thick) and thick (1550 nm thick) anatase coatings and in the mixed anatase/rutile coating (900 nm thick). In the rutile coating (730 nm thick), the columns were denser and had largely lost their feather-like structure. Top-view SEM showed square-pyramidal morphology of the columns in the anatase coatings, with columns generally 100 nm or smaller in size (thin coating) or up to 200 nm across (thick coating). In the mixed anatase/rutile coating, the top-view showed less regular columnar morphology with more elongated columns (up to approx. 100 nm by 200 nm). In the rutile coating, the top-view showed a less ordered, pebble-like morphology.
MG-63 human osteoblast-like cells and RAW 264.7 murine macrophage cells were cultured on the TiO2-coated substrates for 24 or 72 h before quantification of cell proliferation using the WST-1 cell proliferation assay. A toxic response was defined as a reduction in cell viability of greater than 30%. After 24 h culture, proliferation of MG-63 cells was significantly greater than the control (p < 0.05) on the thin anatase and mixed anatase/rutile coatings. After 72 h of culture no significant difference to the control was observed. For RAW 264.7 cells, proliferation was non-significantly decreased compared to the control on all coatings except the rutile coating after 24 h. After 72 h, RAW 264.7 proliferation was significantly decreased (p < 0.01) to 68% and 61% of the control for the thick and thin anatase coatings, respectively, indicating a toxic response. The results indicate that nano-sized TiO2 coatings show different biocompatibility to different test cell types, with a dependence upon coating phase composition and morphology.
SETNanoMetro, a European Seventh Framework project, seeks to develop standard synthetic routes and metrological characterisation methods for the development and production of TiO₂ nanoparticles and nano-sized coatings with highly-defined, homogeneous and reproducible characteristics, including bulk structure, size, shape and surface structure. These materials are being tested for their potential in selected technological applications, including as coatings on bone-substituting prostheses. The objective of this study was to assess how variations in morphology and chemistry of nano-sized TiO₂ coatings affect their biocompatibility in vitro.
We present the synthesis and characterization of multifunctional fluorophore-labeled poly(organosiloxane) nanoparticles with core-shell architecture, where the fluorescent dye is incorporated into the core. Grafting of heterobifunctional poly(ethylene oxide) (PEO) onto the particle surface leads to water-soluble biocompatible nanoparticles. Two different strategies have been used for the synthesis: The encapsulation of dye-labeled monomers during the polycondensation with additional PEO coating and subsequent dye labeling by covalent attachment of the fluorescent dye rhodamine B to the (chloromethylphenyl)siloxane groups in the core after polymerization and grafting of PEO onto the surface. Comparison of the fluorescence quantum yields of the nanoparticles before and after PEO coating show a decrease in quantum yield after PEO coating.
As bio-absorbable implant material the magnesium alloy Mg-1Ca is able to degrade in-vivo. The mechanical properties of this alloy are similar to those of human bone; both Mg and Ca are essential elements in human body. The main problem is the high corrosion rate of this alloy. Two coating systems based on plasma-chemical oxidation and an organic dip coating are applied onto MgCa1.0 magnesium alloy in order to slow down the corrosion rate. The corrosion behaviour of the coated alloys was investigated with electrochemical noise measurements. The influence of hydrogen evolution and increasing pH-value on the cytotoxicity was examined. The results of these investigations suggest that a combination of both coating systems leads to promising degradation properties.