N. Millot

Easy Route to Functionalize Iron Oxide Nanoparticles via Long-Term Stable Thiol Groups

The functionalization of superparamagnetic iron oxide nanoparticles (SPIOs) by meso-2,3-dimercaptosuccinic acid (DMSA) was investigated. Under ambient conditions, the thiol groups from DMSA are not stable and do not allow a direct functionalization without storage in stringent conditions or a chemical regeneration of free thiols. In this study, we have developed a protocol based on poly(ethylene glycol) (PEG) grafting of SPIO prior to DMSA anchoring. We have observed that PEG helps to increase the stability of thiol groups under ambient conditions. The thiol functionalized SPIOs were stable under physiological pH and ionic strength as determined by Ellmans essay and allowed us to graft a thiol reactive fluorescent dye: tetramethylrhodamine-5-maleimide (TMRM).

The radiosensitization effect of titanate nanotubes as a new tool in radiation therapy for glioblastoma: a proof-of-concept.

BACKGROUND AND PURPOSE One of the new challenges to improve radiotherapy is to increase the ionizing effect by using nanoparticles. The interest of titanate nanotubes (TiONts) associated with radiotherapy was evaluated in two human glioblastoma cell lines (SNB-19 and U87MG). MATERIALS AND METHODS Titanate nanotubes were synthetized by the hydrothermal treatment of titanium dioxide powder in a strongly basic NaOH solution. The cytotoxicity of TiONts was evaluated on SNB-19 and U87MG cell lines by cell proliferation assay. The internalization of TiONts was studied using Transmission Electron Microscopy (TEM). Finally, the effect of TiONts on cell radiosensitivity was evaluated using clonogenic assay. Cell cycle distribution was evaluated by flow cytometry after DNA labeling. DNA double-stranded breaks were evaluated using γH2AX labeling. RESULTS Cells internalized TiONts through the possible combination of endocytosis and diffusion with no cytotoxicity. Clonogenic assays showed that cell lines incubated with TiONts were radiosensitized with a decrease in the SF2 parameter for both SNB-19 and U87MG cells. TiONts decreased DNA repair efficiency after irradiation and amplified G2/M cell-cycle arrest. CONCLUSION Our results indicated that further development of TiONts might provide a new useful tool for research and clinical therapy in the field of oncology.

Titanate nanotubes: towards a novel and safer nanovector for cardiomyocytes.

Abstract Actively contractile cardiomyocyte (CM) monolayer represents an interesting tool to study both cardiac diseases and injuries. However, this model is poorly transfectable with conventional agents. Consequently, there is a need to develop new carriers that could overcome this problem. Titanate nanotubes (TiONts) could be a potential candidate due to possibly higher cell uptake as a direct consequence of their shape. On the basis of this rationale, TiONts were assessed for their cytotoxicity and internalization pathways. Cytotoxicity was assessed for TiONts either functionalized with PEI or unfunctionalized and its spherical counterpart P25 TiO2. No cytotoxic effect was observed under TiONts, TiONts-PEI1800 and P25 TiO2 exposed conditions. The tubular morphology was found to be an important parameter promoting internalization while reversing the charge was assessed as non-additional. Internalization was found to occur by endocytosis and diffusion through the membrane. A preliminary transfection study indicated the potential of TiONts as a nanocarrier.

XPS and EELS investigations of chemical homogeneity in nanometer scaled Ti-ferrites obtained by soft chemistry

Abstract Nanocrystalline Ti-ferrites with composition Fe 3− x Ti x O 4 with 0≤ x ≤1 are synthesized using the soft chemistry route. Heterogeneities in precipitate and annealed powders are investigated by a combination of XPS and EELS techniques. As-prepared powder consists in particles with spinel structure and grain size of about 15 nm. Due to high reactivity towards oxygen of nanoparticules, a significant amount of Fe 2+ cations oxidize during precipitation, so that precipitated powders present large deviation from oxygen-metal stoichiometry. Moreover precipitated particles are evidenced to exhibit a strong surface titanium enrichment and an iron richer core. Observation of such cation segregation proves that, during oxide formation process, kinetics of Ti precipitation is slower than that of Fe one. Conditions for tailoring nanocrystalline samples with satisfying composition homogeneity are finally obtained by determination of an appropriate annealing under oxidizing conditions which enables to eliminate Fe–Ti segregation.

Surface adsorption effects on the lattice expansion of copper nanocrystals

Lattice expansion in nanocrystalline copper due to size and surface effect is reported. The lattice parameter is measured by in situ x-ray diffraction at various temperatures from −173°Cto150°C. The experiments are carried out on nanocrystalline copper powders having an average particle size of 40nm. The size effect on the lattice expansion is examined regarding a modified Laplace law, where a surface stress is considered instead of the usual scalar surface energy. The results are discussed taking into account oxidation state and the sorption of molecular species at the nanoparticles surface.

Inelastic neutron scattering due to acoustic vibrations confined in nanoparticles: Theory and experiment

The inelastic scattering of neutrons by nanoparticles due to acoustic vibrational modes (energy below 10 meV) confined in nanoparticles is calculated using the Zemach-Glauber formalism. Such vibrational modes are commonly observed by light-scattering techniques (Brillouin or low-frequency Raman scattering). We also report high-resolution inelastic neutron-scattering measurements for anatase

Zinc oxide nanoparticles mediated cytotoxicity, mitochondrial membrane potential and level of antioxidants in presence of melatonin

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Phthalocyanine–titanate nanotubes: a promising nanocarrier detectable by optical imaging in the so-called imaging window

nanoparticles in a loose powder. Factors enabling the observation of such vibrations are discussed. These include a narrow nanoparticle size distribution which minimizes inhomogeneous broadening of the spectrum and the presence of hydrogen atoms oscillating with the nanoparticle surfaces which enhances the number of scattered neutrons.

Fast and continuous synthesis of nanostructured iron spinel in supercritical water: influence of cations and citrates

Zinc oxide nanoparticles (ZnO NPs) are widely used in a variety of products and are currently being investigated for biomedical applications. However, they have the potential to interact with macromolecules like proteins, lipids and DNA within the cells which makes the safe biomedical application difficult. The toxicity of the ZnO NP is mainly attributed reactive oxygen species (ROS) generation. Different strategies like iron doping, polymer coating and external supply of antioxidants have been evaluated to minimize the toxic potential of ZnO NPs. Melatonin is a hormone secreted by the pineal gland with great antioxidant properties. The melatonin is known to protect cells from ROS inducing external agents like lipopolysaccharides. In the present study, the protective effect of melatonin on ZnO NPs mediated toxicity was evaluated using C6 glial cells. The Cytotoxicity, mitochondrial membrane potential and free radical formation were measured to study the effect of melatonin. Antioxidant assays were done on mice brain slices, incubated with melatonin and ZnO NPs. The results of the study reveal that, instead of imparting a protective effect, the melatonin pre-treatment enhanced the toxicity of ZnO NPs. Melatonin increased antioxidant enzymes in brain slices.

Characterization of ferrites synthesized by mechanical alloying and soft chemistry

TiONts–phthalocyanine nanohybrids combining an efficient optical probe and a promising nanovector have been developed in a step-by-step approach and were thoroughly characterized. Each 150 nm long TiONts–Pc bear ca. 450 Pc. Three nanohybrids were prepared including three different linkers in quest for the best stability.