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

ASSESSMENT OF THE ADSORPTION OF AEROMONAS HYDROPHILA ON POLYTHENE IN SODIUM HYPOCHLORITE AND HYDROGEN PEROXIDE TREATED WATER

A study was carried out on Aeromonas hydrophila adhesion to polythene fragment at different cell growth phases in aquatic microcosm. The main purpose of this study was to assess adsorption capacity, adsorption intensity and kinetics of Aeromonas hydrophila on polythene in sodium hypochlorite (NaOCl) and hydrogen peroxide (H2O2) disinfected water. The mean abundance of adhered A. hydrophila sometimes reached 28 and 111CFU.cm-2 respectively in NaOCl and H2O2 treated water. The adsorption capacities of A. hydrophila cells fluctuated between 1 and 2.12x1057 and between 1 and 2.29x1027 adhered cells.cm-2 in NaOCl and H2O2 disinfected water respectively. The adsorption intensities of this bacterium ranged from -45.81 to 3.49x1019 and from 0.16 to 2.29x1027 respectively in NaOCl and H2O2 treated water. Adsorption capacity and adsorption intensity of A. hydrophila cells on polythene in NaOCl treated water were greater than that obtained in water disinfected with H2O2. Adhesion kinetics of A. hydrophila cells oscillated between 0.001 and 0.930 adhered cell.cm-2.h-1. Adsorption kinetics seem resulted from interactions between bacterial cells and substrates, and depended both on the fragment type and bacterial species. The values of A. hydrophila surface hydrophobicity fluctuated between 65.11 and 92.74% in NaOCl disinfected water and between 63.38 and 89.41% in H2O2 treated water. The mean values of contact angle ranged from 83.1±0.6 to 85.8±0.8°.   Adhesion of A. hydrophila on polythene is mediated amongst others by cell growth phases, cell surface hydrophobicity, cell kinetic adhesion, adsorption capacity and adsorption intensity

Theoretical approach of nanostructuration effects on surface energies

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Impact of two disinfectants on detachment of Enterococcus faecalis from polythene in aquatic microcosm

After cell adhesion processes in microcosm, the impact of sodium hypochlorite (NaOCl) and hydrogen peroxide (H2O2) on the detachment of Enterococcus faecalis from polythene fragments immersed in water under stationary and dynamic conditions was assessed. The abundance of planktonic cells was also evaluated. The density of E. faecalis adhered in absence of disinfectant fluctuated between 2 and 4 units (Log CFU/cm2). After living in disinfected water, the density of E. faecalis remained adhered to polythene sometimes reached 2 units (Log CFU/Cm2). This highest abundance of cells remained adhered was recorded with cells coming from the lag, exponential and stationary growth phases in water treated with 0.5‰ NaOCl. In H2O2 disinfected water, the highest value was recorded at all cells growth phases with 5‰ H2O2 concentration. Adhered E. faecalis cells have been sometimes completely or partially decimated respectively by NaOCl and H2O2 treated water. Considering separately each experimental condition, it was noted that increasing the concentration of disinfectant caused a significant decrease (P≤0.01) in abundance of cells stay adhered after living in water disinfected by the two disinfectants. Changes in disinfectant concentrations in different experimental conditions had an impact on the detachment of E. faecalis cells from the substrates.Â

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

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

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

Nanoporous Surface Wetting Behavior: The Line Tension Influence

International audienc

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