The Use of a Suspension of Functionalized Gadolinium Oxide Nanoparticles for Photocatalytic Applications

International audiencePhoto-degradation of Rhodamine B (RhB) in aqueous solution was use as a probe to assess the photocatalytic activity of Gadolinium oxide (Gd2 O3 ) nanoparticles in suspension under UV irradiation. The nanoparticles in suspension were prepared by a polyol method using gadolinium chloride hexahydrate (Gd2 Cl6 .6H2 O) and diethylene glycol (DEG) as starting precursors. The physico-chemical properties of the elaborated suspension are analyzed using X-ray diffraction (XRD), ultraviolet visible (UV-vis) and infrared (FTIR) spectroscopies, transmission electron microscopy (TEM) and viscosimetry. The Gd2 O3 nanoparticles in suspension were used as photocatalyst for the degradation of Rhodamine B (RhB) dye under irradiation with UV light. The results of the kinetic studies showed that the photodegradation reactions were followed by a pseudo first order reaction rate law over the first 30 minutes of monitoring. The elaborated Gd2 O3 nanoparticles suspension showed a great efficiency in the photocatalytic test without any addition of a co-catalyst, thus limiting the complexity of the further decontamination process of waste water

An Ecoconceptual Synthesis Process of Silver Nanoparticles Integrating the Valorization of a Food Waste: The Peanut Shell

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Boosted Photoactivity of Titania Nanotube Layers Doped with a Suspension of Gold Nanoparticles

International audienceIn the present work, we report on the behavior of synthesized gold nanopar-ticles suspension, incorporated in titanium dioxide nanotube layers (TiO 2-NT) and fabricated by electrochemical anodization in 0.4 wt% hydrofluoric acid solution and we study its photocatalytic response. Gold nanoparticles were characterized using Transmission electron microscopy and X-ray dif-fraction. Scanning electron microscopy was used to study the morphology of TiO 2 nanotube layers doped by gold nanoparticles. Boosted photocatalytic performances on the degradation of an azo dye were obtained by using TiO 2 nanotube layers doped by gold nanoparticles (Au/TiO 2-NT), compared to undoped TiO 2 nanotube layer (TiO 2-NT) catalysts. Under UV irradiation, this new nanomaterial, with noble metal-semi conductor heterojunction (Au/ TiO 2-NT) exhibits a synergetic effect in accelerating the electron transfert, resulting in an enhanced photoactivity recorded in the kinetics of degradation of Acid Orange 7 (AO7). Chronoamperometry was used to highlight higher photocurrent produced by gold-titania interface submited to UV irradiation

Environmental Toxicity and Antimicrobial Efficiency of Titanium Dioxide Nanoparticles in Suspension

International audienceThe aim of this work was to evaluate the photokilling efficiency of synthesized titanium dioxide nanoparticles in suspension. Two strains of Escherichia coli, Lactobacillus casei rhamnosus and Staphylococcus aureus were used as probes to test the photokilling activities of the nanoparticles. The toxicity effects of TiO 2 nanoparticles on the environment were determined by a standard test using gram-negative bioluminescent bacteria Vibrio fischeri. The antimicrobial activity of these nanoparticles (NPs) was then investigated versus NPs concentration, UV irradiation time and mi-cro-organism strains. We evaluated the LC50 values of the nanoparticles suspension by counting the Colony-Forming Units. Results highlighted the differences in bacteria sensitivity facing photo-killing treatment induced by the irradiation of anatase TiO 2 nanoparticles suspension. At the concentration of 1 g·L −1 TiO 2 , tested bacteria were killed after 30 minutes of photo-treatment. Using different TiO 2 concentrations, the Staphylococcus aureus gram-positive/catalase-positive bacteria were more resistant than gram-negative/catalase-positive ones or gram-positive/catalase-negative bacteria. An effect of UV irradiation was evaluated by the quantification of hydrogen peroxide generated by the photolysis of water molecules in presence of the nanoparticles with or without the most resistant bacterium (S. aureus). After 30 minutes with UV irradiation in these two conditions , the concentration of hydrogen peroxide was 35 µM in presence of 1.2 g·L −1 TiO 2 suspension. This result suggested that the resistance mechanism of S. aureus was not due to an extracelullar H 2 O 2 enzymatic degradation

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

International audienceIn 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 electrochemi-cal anodization of Ti foil in 0.4 wt% hydrofluoric acid solution during 20 minutes and then an-nealed 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

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

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Cytotoxicity Study of Gold Nanoparticles on the Basal-Like Triple-Negative HCC-1937 Breast Cancer Cell Line

International audienceThe Triple Negative " Basal-like " breast cancer (TNBL) tumours have a high proliferative capacity and develop a resistance phenotype associated with me-tastases. However, the management of TNBL carcinomas is still not standardized. Among the promising trails, gold nanoparticles could be a relevant tool for the development of a targeted treatment for this breast cancer sub-type in monotherapy, associated and/or conjugated with other drugs. In this work, we report the cytotoxicity impact of gold nanoparticles wrapped in Poly-Ethylene Glycol (PEG) on the TNBL HCC-1937 breast cancer cell line. PEG-coated gold nanoparticles (PEG-Au NPs) were synthesized by a two-step method using a reduction process followed by a post-functionalization called PEGylation. PEG-Au NPs were characterized using transmission electron mi-croscopy and X-ray diffraction. The gold content of the samples was determined using atomic absorption spectrometer. The cytotoxicity tests were performed using Sulforhodamine B survival test and resazurin viability test. PEG-Au NPs impact analysis on HCC1937 TNBL cell line showed a clear toxic action of type dose dependent and at long term. These PEGylated gold nanopar-ticles present a promising tool for the development of tumor-specific radi-osensitizing vectors, with or without the association of other treatment strategies

Feasibility of a Chronic Foreign Body Infection Model Studying the Influence of TiO2 Nanotube Layers on Bacterial Contamination

International audienceBacterial infections on the surface of medical devices are a significant problem in therapeutic approach , especially when implants are used in the living. In cardiology, pacemaker generator pocket surfaces, made in titanium alloy can be colonized by pathogen microorganism. This contamination represents a major risk of sepsis, endocarditis and localized infections for patients. A way to limit this bacterial contamination is to modify the surface topography using nano-structuration process of the titanium alloy surface of the implanted devices. The aim of this study is to evaluate the influence of TiO2 nanotube layers on bacterial infection in the living, considering the feasibility of an animal model of chronic foreign body infection. TiO2 nanotube layers prepared by electro-chemical anodization of Ti foil in 0.4 wt% hydrofluoric acid solution were implanted subcuta-neously in Wistar rats. Three weeks after implantation, TiO2 implants were contaminated by a Staphylococcus epidermilis strain using two different concentrations at 10 6 and 10 8 colony forming unit (CFU) in order to induce a sufficient infection level and to avoid unwanted over infection consequences on rats health during the experiments. After 28 days in the living, 75% of nanotube layers initially submitted to the 10 8 CFU inoculum were contaminated while only 25% nanotube layers initially submitted to the 10 6 CFU inoculum remained infected. This significant result underlines the influence of TiO2 nanotube layers in decreasing the infection level. Our in vitro experiments showed that the synthesized TiO2 nanotubes indeed decreased the Staphylcoccus epider-mis adhesion compared to unanodized Ti foil

Functional and antimicrobial properties of herbal nanocomposites from Piper betle plant leaves for enhanced cotton fabrics

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Fluorescent Gold Nanoparticles in Suspension as an Efficient Theranostic Agent for Highly Radio-Resistant Cancer Cells

International audienceGold nanoparticles are a promising candidate for developing new strategies of therapy against cancer. Due to their high atomic number and relative biocompatibility, they are commonly investigated as radiosensitizers to locally increase the dose of radiotherapy. In order to optimize this radiosensitizing effect, it is necessary to control the positioning of the nanoparticles in the cells. The purpose of this study is to investigate, by means of fluorescent gold nanoparticles in suspension, the dose enhancement on highly radio-resistant cancer cells. These nanoparticles were successfully produced using modern click-chemistry methods, first by attaching a chelating agent Diethylenetriamine pentaacetate benzylamine to L-cysteine, bonding the resulting ligand to a gold core, grafting propargylamine and then utilizing copper-catalyzed azide-alkyne cycloaddition (CuAAC) to fuse AlexaFluor 647 to the ligands. The results of this study prove the success of the reactions to produce a minimally cytotoxic and highly stable nanoparticle suspension that increases the radiosensitivity of gliosarcoma 9L tumor cells, with a 35% increase in cell death using 5 Gy kilovoltage radiation. Their fluorescent functionalization allowed for their simple localization within living cells and detection in vivo post-mortem