Tunable Functionality and toxicity studies of Titanium Dioxide Nanotube Layers

In this work, we have developed economic process to elaborate scalable titanium dioxide nanotube layers which show a tunable functionality. The titanium dioxide nanotube layers was prepared by electrochemical anodization of Ti foil in 0.4 wt% hydrofluoric acid solution. The nanotube layers structure and morphology were characterized using x-ray diffraction and scanning electron microscopy. The surface topography and wettability was studied according to the anodization time. The sample synthesized while the current density reached a local minimum displayed higher contact angle. Beyond this point, the contact angles decrease with the anodization time. Photo-degradation of acid orange 7 in aqueous solution was used as a probe to assess the photo-catalytic activity of titanium dioxide nanotube layers under UV irradiation. We obtained better photocatalitic activity for the sample elaborate at higher current density. Finally we use the Ciliated Protozoan T. pyriformis, an alternative cell model used for in vitro toxicity studies, to predict the toxicity of titanium dioxide nanotube layers in biological system. We did not observe any characteristic effect in the presence of the titanium dioxide nanotube layers on two physiological parameters related to this organism, non-specific esterases activity and population growth rate

Contrôle de la structure de matériaux moulésen acier inoxydable austénitique Z2 NCDU 25.20.04-M et en alliage base nickel NC16D16Fe5W5-M par balayage potentiocinétique du domaine actif vers son domaine passif du matériau dans un électrolyte choisi

La technique EPR DL (Electrochemical Potentiokinetic Reactivation Double Loop) permet la détection et la quantification de zones déchromées. Cette déchromisation provoque une destruction locale du film passif autour des carbures de chrome ou des phases intermétalliques à base de chrome (phase σ, χ...). La conjonction d’un milieu corrosif et de zones appauvries en chrome est à l’origine d’un phénomène de corrosion intergranulaire (CIG). Cette étude a pour but la mise au point de conditions d’essais du test EPR dans l’optique de contrôler in situ la structure de matériaux moulés. Nous avons recherché un électrolyte suffisamment sensible ainsi que des conditions opératoires pour une mise en application aisée sur site. L’étude est menée sur deux alliages :

Fabrication of TiO2 Nanotanks Embedded in a Nanoporous Alumina Template

The feasibility of surface nanopatterning with TiO2 nanotanks embedded in a nanoporous alumina template was investigated. Self-assembled anodized aluminium oxide (AAO) template, in conjunction with sol gel process, was used to fabricate this nanocomposite object. Through hydrolysis and condensation of the titanium alkoxide, an inorganic TiO2 gel was moulded within the nanopore cavities of the alumina template. The nanocomposite object underwent two thermal treatments to stabilize and crystallize the TiO2. The morphology of the nanocomposite object was characterized by Field Emission Scanning Electron Microscopy (FESEM). The TiO2 nanotanks obtained have cylindrical shapes and are approximately 69 nm in diameter with a tank-to-tank distance of 26 nm. X-ray diffraction analyses performed by Transmission Electron Microscopy (TEM) with selected area electron diffraction (SAED) were used to investigate the TiO2 structure. The optical properties were studied using UV-Vis spectroscopy

Photoactive TiO2 antibacterial coating on surgical external fixation pins for clinical application

Guillaume Villatte,1,2 Christophe Massard,1 Stéphane Descamps,1,2 Yves Sibaud,1 Christiane Forestier,3 Komla-Oscar Awitor1 1Laboratory C-Biosenss EA 4676, Clermont-Ferrand University, Université d’Auvergne, Clermont-Ferrand, France; 2Department of Orthopedics, Clermont-Ferrand University Hospital (CHU), Clermont-Ferrand, France; 3Laboratory Microorganism UMR 6023, Clermont-Ferrand University, Université d’Auvergne, Clermont-Ferrand, France Abstract: External fixation is a method of osteosynthesis currently used in traumatology and orthopedic surgery. Pin tract infection is a common problem in clinical practice. Infection occurs after bacterial colonization of the pin due to its contact with skin and the local environment. One way to prevent such local contamination is to create a specific coating that could be applied in the medical field. In this work, we developed a surface coating for external fixator pins based on the photocatalytic properties of titanium dioxide, producing a bactericidal effect with sufficient mechanical strength to be compatible with surgical use. The morphology and structure of the sol-gel coating layers were characterized using, respectively, scanning electron microscopy and X-ray diffraction. The resistance properties of the coating were investigated by mechanical testing. Photodegradation of acid orange 7 in aqueous solution was used as a probe to assess the photocatalytic activity of the titanium dioxide layers under ultraviolet irradiation. The bactericidal effect induced by the process was evaluated against two strains, ie, Staphylococcus aureus and multiresistant Staphylococcus epidermidis. The coated pins showed good mechanical strength and an efficient antibacterial effect after 1 hour of ultraviolet irradiation. Keywords: hybrid sol-gel, external pin fixation, titanium dioxide, antibacterial effect, mechanical strength, ultraviolet photoactivit

Impact of Annealing Treatment on the Behaviour of Titanium Dioxide Nanotube Layers

Abstract In this work, we study the influence of the annealing treatment on the behaviour of titanium dioxide nanotube layers. The heat treatment protocol is actually the key parameter to induce stable oxide layers and needs to be better understood. Nanotube layers were prepared by electrochemical anodization of Ti foil in 0.4 wt% hydrofluoric acid solution during 20 minutes and then annealed in air atmosphere. In-situ X-ray diffraction analysis, coupled with thermogravimetry, gives us an inside on the oxidation behaviour of titanium dioxide nanotube layers compared to bulk reference samples. Structural studies were performed at 700˚C for 12 h in order to follow the time consequences on the oxidation of the material, in sufficient stability conditions. In-situ XRD brought to light that the amorphous oxide layer induced by anodization is responsible for the simultaneous growths of anatase and rutile phase during the first 30 minutes of annealing while the bulk sample oxidation leads to the nucleation of a small amount of anatase TiO2. The initial amorphous oxide layer created by anodization is also responsible for the delay in crystallization compared to the bulk sample. Thermogravimetric analysis exhibits parabolic shape of the mass gain for both anodized and bulk sample; this kinetics is caused by the formation of a rutile external protective layer, as depicted by the associated in-situ XRD diffractograms. We recorded that titanium dioxide nanotube layers exhibit a lower mean mass gain than the bulk, because of the presence of an initial amorphous oxide layer on anodized samples. In-situ XRD results also provide accurate information concerning the sub-layers behavior during the annealing treatment for the bulk and nanostructured layer. Anatase crystallites are mainly localized at the interface oxide layer-metal and the rutile is at the external interface. Sample surface topography was characte-* Corresponding author. M. Siampiringue et al. 143 rized using scanning electron microscopy (SEM). As a probe of the photoactivity of the annealed TiO 2 nanotube layers, degradation of an acid orange 7 (AO7) dye solution and 4-chlorophenol under UV irradiation (at 365 nm) were performed. Such titanium dioxide nanotube layers show an efficient photocatalytic activity and the analytical results confirm the degradation mechanism of the 4-chlorophenol reported elsewhere

Photopolymerizable hybrid sol gel coating as a barrier against plasticizer release

International audienceIn this work, a dip-coating method was applied to coat polyvinyl chloride (PVC) used in the field of medicine with an organic/inorganic sol gel hybrid layer based on two organic functionalized titanium alkoxide and organic grafted alkoxysilane. The aim of the coating is to prevent the plasticizers release from PVC and to protect PVC against UV degradation. The optical and structural properties of the coating were investigated using UV–visible and infrared spectroscopy. ATR-FTIR spectroscopy was performed to control the amount of plasticizer leaching from the PVC medical device. The mechanical properties of the PVC and coated PVC samples were determined using tensile test. The barrier effect of the hybrid sol gel on the migration of the plasticizers was assessed using high performance liquid chromatography. Surprisingly the coating protects the PVC substrate against the UVA degradation and prevents leaching of plasticizers up to 98%. The adhesion of the hybrid coating on PVC exhibits a constant value whatever the treatments (UV-ozone and plasma) performed on the polymer surface

Photopolymerizable hybrid sol gel coating as a barrier against plasticizer release

International audienceIn this work, a dip-coating method was applied to coat polyvinyl chloride (PVC) used in the field of medicine with an organic/inorganic sol gel hybrid layer based on two organic functionalized titanium alkoxide and organic grafted alkoxysilane. The aim of the coating is to prevent the plasticizers release from PVC and to protect PVC against UV degradation. The optical and structural properties of the coating were investigated using UV–visible and infrared spectroscopy. ATR-FTIR spectroscopy was performed to control the amount of plasticizer leaching from the PVC medical device. The mechanical properties of the PVC and coated PVC samples were determined using tensile test. The barrier effect of the hybrid sol gel on the migration of the plasticizers was assessed using high performance liquid chromatography. Surprisingly the coating protects the PVC substrate against the UVA degradation and prevents leaching of plasticizers up to 98%. The adhesion of the hybrid coating on PVC exhibits a constant value whatever the treatments (UV-ozone and plasma) performed on the polymer surface

Photopolymerizable hybrid sol gel coating as a barrier against plasticizer release

International audienc