Chrystelle Neaime

Characterization and Luminescence Properties of Lanthanide-Based Polynuclear Complexes Nanoaggregates

For the first time, hexanuclear complexes with general chemical formula [Ln6O(OH)8(NO3)6(H2O)n](2+) with n = 12 for Ln = Sm-Lu and Y and n = 14 for Ln = Pr and Nd were stabilized as nanoaggregates in ethylene glycol (EG). These unprecedented nanoaggregates were structurally characterized by (89)Y and (1)H NMR spectroscopy, UV-vis absorption and luminescence spectroscopies, electrospray ionization mass spectrometry, diffusion ordered spectroscopy, transmission electron microscopy, and dynamic light scattering. These nanoaggregates present a 200 nm mean solvodynamic diameter. In these nanoaggregates, hexanuclear complexes are isolated and solvated by EG molecules. The replacement of ethylene glycol by 2-hydroxybenzyl alcohol provides new nanoaggregates that present an antenna effect toward lanthanide ions. This results in a significant enhancement of the luminescence properties of the aggregates and demonstrates the suitability of the strategy for obtaining highly tunable luminescent solutions.

Voltage-Driven Photoluminescence Modulation of Liquid-Crystalline Hybridized ZnO Nanoparticles

Liquid-crystalline hybrid nanomaterials have been obtained by grafting mesogenic units around luminescent ZnO nanocrystals of 5 nm in diameter. Modifying the mesogenic density around the inorganic core allows the modulation of the liquid-crystalline behavior and its miscibility in commercial liquid crystal (LC). The strong blue photoluminescence observed for the hybrids can be modulated by applying a voltage on a LC cell containing commercial LC and 10 wt % of hybrid.

Robust Method Using Online Steric Exclusion Chromatography-Ultraviolet-Inductively Coupled Plasma Mass Spectrometry To Investigate Nanoparticle Fate and Behavior in Environmental Samples.

The foundation of nanoscience is that the properties of materials change as a function of their physical dimensions, and nanotechnology exploits this premise by applying selected property modifications for a specific benefit. However, to investigate the fate and effect of the engineered nanoparticles on toxic metal (TM) mobility, the analytical limitations in a natural environment remain a critical problem to overcome. Recently, a new generation of size exclusion chromatography (SEC) columns developed with spherical silica is available for pore sizes between 5 and 400 nm, allowing the analysis of nanoparticles. In this study, these columns were applied to the analysis of metal-based nanoparticles in environmental and artificial samples. The new method allows quantitative measurements of the interactions among nanoparticles, organic matter, and metals. Moreover, because of the new nanoscale SEC, our method allows the study of these interactions for different size ranges of nanoparticles and weights of organic molecules with a precision of 1.2 × 10(-2) kDa. The method was successfully applied to the study of nanomagnetite spiked in complex matrixes, such as sewage sludge, groundwater, tap water, and different artificial samples containing Leonardite humic acid and different toxic metals (i.e., As, Pb, Th). Finally, our results showed that different types of interactions, such as adsorption, stabilization, and/or destabilization of nanomagnetite could be observed using this new method.

Evaluation of functional SiO2 nanoparticles toxicity by a 3D culture model

CONTEXT as a kind of non-metal oxide SiO2 NPs have been extensively used in biomedicine, pharmaceuticals and other industrial manufacturing fields, such as DNA delivery, cancer therapy… Our group had developed a method based on microemulsion process to prepare SiO2 NPs incorporating photonic or magnetic nanocrystals and luminescent nanosized inorganic metal atom clusters. However, the toxicity of nanoparticles is known to be closely related to their physico-chemical characteristics and chemical composition. OBJECT it is therefore of interest to investigate the toxicity of these novel SiO2 NPs to the cells that may come in contact. MATERIALS AND METHODS the potential toxic effect of the functional @SiO2 NPs containing Mo6 clusters with or without gold nanoparticles was investigated, at concentrations 1 μg/mL, 10 μg/mL and 100 μg/mL each, on three different cell lines. Cell viability was measured by the MTT test in monolayers culture whereas the cytotoxicity in spheroid model was examined by the APH assay. In a second time, oxidative-stress-induced cytotoxicity was investigated through glutathione levels dosages. RESULTS the results indicated that both A549 and L929 cell lines did not exhibit susceptibility to functional @SiO2 NPs-induced oxidative stress unlike KB cells. DISCUSSION SiO2 NPs containing CMB may become toxic to cultured cells but only at a very high dosage level. Therefore, this toxicity depends on cell lines and more, on the model of cell cultures. The selection of appropriate cell line remains a critical component in nanotoxicology. CONCLUSION these results are relevant to future applications of SiO2 gold-cluster NPs in controlled release applications.

Magnetic and Fluorescent Hybrid Silica Nanoparticles Based on the Co-Encapsulation of γ-Fe 2 O 3 Nanocristals and [Mo 6 Br 14 ] 2- Luminescent Nanosized Clusters by Water-in-Oil Microemulsion

The design, synthesis and characterization of magnetic-luminescent nanoparticles is now more and more studied since the last decade. However, optimizing the design of such materials requires a deep understanding of their physico-chemical properties. In this paper are reported extended investigations on luminescent and magnetic @SiO2 Nps prepared by a water-in-oil microemulsion technique. The Cs2[Mo6Br14] cluster compound is used as red-NIR phosphor and is prepared by solid state chemistry. We bring here new insights into the structure of such Nps and its interplay with their optical or magnetic properties.

Multi-Functional Silica Nanoparticles Based on Metal Atom Clusters: From Design to Toxicological Studies

We report on the interest of luminescent and nanosized metal atom clusters for the development of functional silica nanoparticles. Furthermore, multi-functional hybrid nanoparticles have been achieved by associating these luminescent clusters with magnetic γ-Fe2O3 nanocrystals and plasmonic gold nanocrystals. In addition, as part of the risk evaluation before potential applications, the toxicity of the nanoparticles was evaluated both on plants and on human cells.

Band-Gap Engineering Based on Ti@ZnO Nanocolloids: Tunable Optical Properties

One of the largest application areas of sol-gel chemistry is thin-film preparation. Using this approach, we started to synthesize M@ZnO colloidal solutions for the preparation of functional thin films. ZnO is a wide band-gap (3.37 eV) semiconductor with large exciton binding energy. In the bulk or in nanosized form, it could be used in a wide range of applications such as UV light emitters, spin functional devices, gas sensors, transparent electronics or surface acoustic wave devices. Since recently, the preparation of innovative functional M@ZnO materials by doping or functionalizing nanocolloids constitutes a new challenge. Using high concentrations of the different Ti@ZnO nanocolloids, we were able to prepare various functional colloidal solutions with tunable emission and thin films, such as red-luminescent Eu3+@ZnTiO3 or versatile ZnTiON colored nanomaterials.