Antoine Thill

Bio: Antoine Thill is an academic researcher from Université Paris-Saclay. The author has contributed to research in topics: Imogolite & Nanoparticle. The author has an hindex of 32, co-authored 76 publications receiving 3159 citations. Previous affiliations of Antoine Thill include Bhabha Atomic Research Centre & Commissariat à l'énergie atomique et aux énergies alternatives.

Cytotoxicity of CeO2 nanoparticles for Escherichia coli. Physico-chemical insight of the cytotoxicity mechanism

Abstract: The production of nanoparticles (NPs) is increasing rapidly for applications in electronics, chemistry, and biology. This interest is due to the very small size of NPs which provides them with many interesting properties such as rapid diffusion, high specific surface areas, reactivity in liquid or gas phase, and a size close to biomacromolecules. In turn, these extreme abilities might be a problem when considering a potentially uncontrolled exposure to the environment. For instance, nanoparticles might be highly mobile and rapidly transported in the environment or inside the body through a water or air pathway. Accordingly, the very fast development of these new synthetic nanomaterials raises questions about their impact on the environment and human health. We have studied the impact of a model water dispersion of nanoparticles (7 nm CeO2 oxide) on a Gram-negative bacteria (Escherichia coli). The nanoparticles are positively charged at neutral pH and thus display a strong electrostatic attraction toward b...

CeO2 nanoparticles induce DNA damage towards human dermal fibroblasts in vitro

Abstract: Cerium dioxide nanoparticles have been proposed for an increasing number of applications in biomedicine, cosmetic, as polishing materials and also as byproducts from automotive fuel additives. The aim of this study was to examine the potential in vitro cyto- and genotoxicity of nano-sized CeO2 (7 nm) on human dermal fibroblasts. By combining a physicochemical and a (geno)toxicological approach, we defined the causal mechanisms linking the physico-chemical properties of nano-CeO2 with their biological effects. Using X-ray absorption spectroscopy, we observed a reduction of 21 +/- 4% of the Ce4+ atoms localized at the surface of CeO2 nanoparticles due to the interactions with organic molecules present in biological media. These particles induced strong DNA lesions and chromosome damage related to an oxidative stress. These genotoxic effects occurred at very low doses, which highlighted the importance of a genotoxicological approach during the assessment of the toxicity of nanoparticles.

Heteroaggregation of Titanium Dioxide Nanoparticles with Model Natural Colloids under Environmentally Relevant Conditions

Abstract: The heteroaggregation of engineered nanoparticles (ENPs) with natural colloids (NCs), which are ubiquitous in natural surface waters, is a crucial process affecting the environmental transport and fate of ENPs. Attachment efficiencies for heteroaggregation, αhetero, are required as input parameters in environmental fate models to predict ENP concentrations and contribute to ENP risk assessment. Here, we present a novel method for determining αhetero values by using a combination of laser diffraction measurements and aggregation modeling based on the Smoluchowski equation. Titanium dioxide nanoparticles (TiO2 NPs, 15 nm) were used to demonstrate this new approach together with larger silicon dioxide particles (SiO2, 0.5 ?m) representing NCs. Heteroaggregation experiments were performed at different environmentally relevant solution conditions. At pH 5 the TiO2 NPs and the SiO2 particles are of opposite charge, resulting in αhetero values close to 1. At pH 8, where all particles are negatively charged, αhetero was strongly affected by the solution conditions, with αhetero ranging from <0.001 at low ionic strength to 1 at conditions with high NaCl or CaCl2 concentrations. The presence of humic acid stabilized the system against heteroaggregation.

Direct and indirect CeO2 nanoparticles toxicity for Escherichia coli and Synechocystis

Abstract: Physico-chemical interactions between nanoparticles and cell membranes play a crucial role in determining the cytotoxicity of nanoparticles, which may thereby vary depending on the nature of the ta...

Fast parallel algorithms for short-range molecular dynamics

Abstract: Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

Nanomaterials in the environment: Behavior, fate, bioavailability, and effects

Abstract: The recent advances in nanotechnology and the corresponding increase in the use of nanomaterials in products in every sector of society have resulted in uncertainties regarding environmental impacts. The objectives of this review are to introduce the key aspects pertaining to nanomaterials in the environment and to discuss what is known concerning their fate, behavior, disposition, and toxicity, with a particular focus on those that make up manufactured nanomaterials. This review critiques existing nanomaterial research in freshwater, marine, and soil environments. It illustrates the paucity of existing research and demonstrates the need for additional research. Environmental scientists are encouraged to base this research on existing studies on colloidal behavior and toxicology. The need for standard reference and testing materials as well as methodology for suspension preparation and testing is also discussed.