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

Nanoporous Surface Wetting Behavior: The Line Tension Influence

International audienceThe aim of this work is to develop a physical model to describe the evolution of the apparent contact angle for four different liquids on nanotextured alumina surfaces with different pore radius. The nanoporous alumina templates were fabricated by anodization of Al foil in a 0.3 M oxalic acid solution. Scanning electron microscopy was used to characterize the morphology of the surfaces. The templates are approximately 400 nm in thickness and consist of a well-ordered hexagonal array of uniform radius pores spaced 105 nm apart with pore radii from 12 to 42 nm. The wettability of nanoporous alumina templates was investigated using contact-angle measurements. We measured the contact angles using four liquids: water, ethylene glycol, aniline, and a mixture of ethylene glycol and aniline. We developed a new theoretical model for the contact angle on nanoporous surfaces as a function of the pore radius. This model is based on energy considerations and involves liquid penetration into the nanopores driven by the capillarity (Laplace's law). Because the air is compressed inside the pores, this model also includes the effect of the line tension. This is important because the three-phase line length is greatly enhanced in our nanoporous structures. For example: for a millimeter-sized droplet, the three-phase line around the perimeter of the droplet is a few millimeters long, whereas the total three-phase line within the pores can reach several tens of meters. Using our model, the line-tension value for our nanopore samples is positive and ranges from 4 to 13 × 10 −9 N, which falls within the wide interval from 10 −11 to 10 −5 N quoted in the literature. Nanoporous surfaces may allow the effect of line tension to be visible for micro-to macrodroplets

Nanoporous Surface Wetting Behavior: The Line Tension Influence

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In vitro evaluation of TiO2 nanotubes as cefuroxime carriers on orthopaedic implants for the prevention of periprosthetic joint infections

International audienceObjective: In this study, the influence of several parameters that could impact the use of titanium dioxide nanotubes as cefuroxime carriers was investigated.Method: Cefuroxime loading and release was studied for 90 min with three nano-topography conditions (nano-smooth, nano-rugged and nano-tubular), two cefuroxime loading solution concentrations (150 mg/mL and 25 mg/mL) and two nano-tubular crystalline structures.Results: In all tested conditions, maximum amount of cefuroxime was obtained within 2 min. For both cefuroxime loading solution concentrations, nano-smooth samples released the least cefuroxime, and the nano-tubular samples released the most, and a six-fold increase in the concentration of the cefuroxime loading increased the amount of cefuroxime quantified by more than seven times, for all tested nano-topographies. However, the nano-tubes’ crystalline structure did not have any influence on the amount of cefuroxime quantified.Conclusion: The results demonstrated that the surface nano-topography and loading solution concentration influence the efficiency of titanium dioxide nanotubes as cefuroxime carriers and need to be optimized for use as novel reservoirs for local delivery of cefuroxime to prevent periprosthetic infections

Stability of an ophthalmic micellar formulation of cyclosporine A in unopened multidose eyedroppers and in simulated use conditions

International audienceCyclosporine A eye drops are used at concentrations ranging from 0.5 to 20 mg/mL to treat a variety of ophthalmic diseases. Cyclosporine A formulations at high concentrations are difficult to manufacture because of cyclosporine's lipophilicity, and generally require an oil based vector. In this study, we investigated the physicochemical and microbiological stability of two high concentrations (10 mg/mL and 20 mg/mL) of an ophthalmic cyclosporine A micellar solution in a low density polyethylene multidose eyedropper, at two conservation conditions (5 °C and 25 °C), before and with simulated use. Analyses used were the following: visual inspection, cyclosporine quantification by a stability-indicating liquid chromatography method, osmolality and pH measurements and turbidity. A complementary analysis by dynamic light scattering was implemented to evaluate potential particle formation or micelle size change. In the in-use study, cyclosporine quantification was also performed on the drops emitted from the multidose eyedroppers. Our results show that the cyclosporine micellar formulation retains good physicochemical and microbiological stability, as all parameters stayed within acceptable range limits, however a higher variability in cyclosporine concentrations was observed for 20 mg/mL units stored at 25 °C. The in-use study showed that cyclosporine concentrations in the emitted drops were also within acceptable range limits. The micellar formulation presented in this study can therefore be stored at 5 °C or at ≤ 25 °C for up to 6 months

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

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