Toxicity assessment of ZnO-decorated Au nanoparticles in the Mediterranean clam Ruditapes decussatus

The synthesis of hybrid nanomaterials has greatly increased in recent years due to their special physical and chemical properties. However, information regarding the environmental toxicity associated with these chemicals is limited, in particular in the aquatic environment. In the present study, an experiment was performed in which the marine bivalve (Ruditapes decussatus) was exposed for 14 days to 2 concentrations of zinc oxide-decorated Au nanoparticles (Au-ZnONPs: Au-ZnONP50 = 50 μg/L; Au-ZnONP100 = 100 μg/L). The stability and resistance of Au-ZnONPs in the natural seawater were assessed by combining transmission electron microscopy and dynamic light scattering. Inductively coupled plasma-atomic emission spectroscopy revealed uptake of these nanoparticles within clams and their ability to induce metallic deregulation. The results obtained indicate that Au-ZnONPs induce biochemical and histological alterations within either the digestive gland or gill tissues at high concentration. This was deduced from the significant increase in H2O2 level, superoxide dismutase and catalase activities and malondialdehyde content. Furthermore, the toxicity of Au-ZnO nanoparticles was linked with the increase of intracellular iron and calcium levels in both tissues. Histological alterations in gill and digestive gland were more pronounced with Au-ZnONP100 and this is likely related to oxidative mechanisms. Gill and digestive gland are differentially sensitive to Au-ZnONPs if the exposure concentration is higher than 50 μg/L. In conclusion, the parameters considered here could constitute reliable biomarkers for evaluation of hybrid nanoparticles toxicity in environmental model organisms. In addition, based on the results obtained, gill and digestive gland of R. decussatus could be proposed as models to detect harmful effects of hybrid nanoparticles

Triangular gold nanoparticles modify shell characteristics and increase antioxidant enzyme activities in the clam Ruditapes decussatus

Context: Nanoparticles may cause adverse environmental effects but there is limited information on their interactions with marine organisms. Objective: Our aim was to examine the effects of triangular gold nanoparticles (Tr-Au NPs) on the clam, Ruditapes decussatus. Materials and methods: Clams were exposed to Tr-Au1 = 5 µg/L and Tr-Au2 = 10 µg/L for 2 and 7 days. Effects on shell structure were investigated. Superoxide dismutase (SOD), catalase (CAT), glutathione transferase (GST) activities, protein carbonyl levels and malondialdehyde content were used to assess biochemical status. Results: Transmission electron microscopy (TEM) and electron dispersive X-ray microanalysis (EDX) showed that Tr-Au NPs modified shell structure and morphology. Tr-Au NPs size increased forming aggregate particles. Tr-Au NPs increased SOD, CAT and GST activities in gill and digestive gland in a concentration- and time-dependent manner indicating defence against oxidative stress. Enhanced lipid peroxidation and protein carbonyl levels confirmed oxidative stress. Conclusion: Tr-Au NPs cause oxidative stress and affect shell structure of clams. These findings may have relevance to other marine species

Evaluation of an early marker of chronic renal graft dysfunction : Urinary PCR of Vimentin mRNA

La dysfonction chronique du greffon est la cause majeure d’échec en transplantation rénale, que son mécanisme soit immunologique ou non. Lorsque l’épithélium tubulaire rénal subit des changements phénotypiques épithéliaux (CPE), évocateurs de transition épithélio-mésenchymateuse (TEM) et associés au développement de lésions irréversibles de fibrose interstitielle et d’atrophie tubulaire, l’évolution se fait vers la diminution de la fonction rénale et de la perte du greffon. Nous avons étudié le phénotype de l’épithélium tubulaire rénal par immunohistochimie et par la mesure dans les urines des ARN messagers de la vimentine, CD45, GAPDH et Uroplakine 1a par RT-PCR. Nous avons comparé les greffes avec donneurs cadavériques et celles avec donneurs vivants et nous avons évalué les performances diagnostiques de la RT-PCR dans les urines pour le diagnostic de CPE chez les patients greffés, ayant une biopsie rénale de surveillance à 3 mois et une biopsie sur indication particulière. Nous avons montré que le score de TEM sur la biopsie de surveillance et l’évolution de la fonction rénale sont meilleurs chez les greffés à partir de donneur vivant, comparé à ceux ayant un greffon de donneur cadavérique. La valeur de l’ARNm de la vimentine et CD45 rapportée à l’uroplakine 1a est corrélée avec le score de vimentine en immunomarquage dans les biopsies de surveillance. Ces biomarqueurs pourraient être utilisés comme un outil non invasif pour surveiller la fibrogénèse dans le greffon rénal. Ce test pourrait être utilisé pour le dépistage précoce des pathologies fibrosantes du greffon rénal. Une étude transcriptomique indépendante a été réalisée, confirmant l’intérêt de la normalisation des ARN messagers par l’ARNm de l’uroplakine, et montrantChronic graft dysfunction is the major cause for end-stage renal failure after renal transplantation, both through immune and non-immune mechanisms. When the renal tubular epithelium undergoes epithelial phenotypic changes (EPC), reminiscent of epithelial mesenchymal transition (EMT), and associated with interstitial fibrosis and tubular atrophy, the prognosis is poor with a diminution of renal function and graft loss. In this prospective study. We studied the renal epithelial phenotype by immunohistochemistry and measured mRNA in urine of vimentin, CD45, GAPDH and uroplakin 1a by RT-PCR. We compared grafts from living donors and those from deceased donors. We evaluated the diagnostic performance of RT-PCR on urine for the diagnosis of epithelial phenotypic changes in transplant patients, with renal biopsy surveillance at 3 months and a biopsy on particular indication. We have shown that the EMT score on renal biopsy surveillance and the evolution of graft renal function were better in the patients from living donors than in those from cadaveric donors. The value of the mRNA of vimentin and CD45 relative to the uroplakin is correlated with the score in vimentin immunostaining in routine biopsies. These biomarkers could be used as a noninvasive tool to monitor the renal graft fibrogenesis. This test could be used for early detection of fibrotic diseases of the kidney transplant. In an independant study, the transcriptome in urine was analyzed, and it was found that normalization of mRNA with uroplakin mRNA was useful, and that EPC were associated with immune and inflammatory profiles

Hybrid Au–Fe₃O₄ Nanoparticles: Plasmonic, Surface Enhanced Raman Scattering, and Phase Transition Properties

In this work, we report on the synthesis of hybrid Au–Fe₃O₄ nanoparticles (NPs) using a novel one-pot synthesis method that makes use of triethylene glycol as a solvent, a reducing agent, and a stabilizing layer. The produced nanoparticles consist of Au cores decorated with magnetite Fe₃O₄ nanoparticles. Optical absorption measurements combined with numerical simulations showed that the Au–Fe₃O₄ nanoparticles exhibit a localized surface plasmon resonance clearly red-shifted with respect to that of bare Au nanoparticles. This strong plasmonic resonance is exploited to produce surface-enhanced Raman scattering (SERS) from both the organic molecules and the iron oxide surrounding the Au cores. We found that the SERS signal exhibits strong temporal fluctuations which are used to identify the origin of the observed Raman lines. In particular, we clearly point out the presence of an iron hydroxide (γ-FeOOH) layer at the surface of the Fe₃O₄ nanoparticles forming the shell. This result is supported by numerical simulations of the plasmonic near field generated by the Raman probe. Moreover, we investigate the light-induced phase transition from magnetite to hematite (α-Fe₂O₃). Owing to the strong SERS effect we were able to detect the formation of diiron-oxo bonds during the phase transition. These bonds are ascribed to the presence of a mixed magnetite/maghemite phase. We thus propose a new scheme where the phase transition is triggered by the iron hydroxide surface layer. Such a transition is here studied for the first time in Au–Fe₃O₄ hybrid nanoparticles where the gold cores act as plasmonic nanoheaters responsible for the thermally induced phase transition

La transition épithélio-mésenchymateuse et la fibrose du transplant rénal

La transition épithélio-mésenchymateuse (TEM) est un processus par lequel les cellules épithéliales différenciées subissent une conversion phénotypique et acquièrent un phénotype de cellules mésenchymateuses. Outre la morphologie allongée, s’y associent une capacité migratoire et une production accrue des composants de la matrice extracellulaire (MEC). Ce phénomène joue un rôle essentiel dans le développement embryonnaire, la cicatrisation et la régénération tissulaire. Certaines études ont suggéré que les cellules épithéliales tubulaires rénales, en réponse à une agression, se transforment en cellules mésenchymateuses, constituant une source importante de nouveaux myofibroblastes qui envahissent l’interstitium rénal et contribuent à la fibrose au sein de celui-ci. Cependant, un nombre croissant de travaux ont remis en question l’existence réelle de ce processus in vivo, qui reste un sujet de débat intense, et pourrait dépendre du modèle étudié. Dans cette revue, nous faisons le point sur le rôle de la TEM dans le développement de la fibrose du greffon rénal, puis nous proposons des approches pour la détection et le traitement de la fibrogenèse rénale, basées sur ce processus de TEM

Nanoparticles influence the herbicide diuron mediated toxicity on marine mussel Mytilus galloprovincialis: single and mixture exposure study

The exposure of habitats to the herbicide diuron, one of the most effective and highly used antifouling agents worldwide, leads to serious environmental toxicity, mainly for marine invertebrates. Moreover, nanoparticles (NPs) act as carriers of organic pollutants in marine ecosystems, thereby influencing their bioaccumulation and toxicity in exposed organisms. This study aimed to investigate the individual and combined toxicity of diuron and two NPs (ZnO NPs and TiO _2 NPs) at sub-lethal doses on the marine mussel Mytilus galloprovincialis

Comparative Study of Ni- and Co-Substituted ZnO Nanoparticles: Synthesis, Optical, and Magnetic Properties

International audienceNi- and Co-substituted ZnO nanoparticles were synthesized using forced hydrolysis of acetate metallic salts in a polyol medium. The X-ray diffraction patterns show a hexagonal wurtzite structure (space group P63mc). The characteristic absorption bands of UV-vis-IR spectra are correlated with the d-d transitions of tetrahedrally coordinated Co2+ and Ni2+ ions in octahedral and tetrahedral sites. The photoluminescence spectra exhibited a typical ZnO UV-exitonic emission band around 380 nm and a broad band between 400 and 500 nm that might be ascribed to the intrinsic defects in the ZnO material. The transmission electron microscopy displays spherical particles with a diameter between 20 and 30 nm. The magnetic measurements reveal that Zn1-xNixO and Zn1-xCoxO nanoparticles show, respectively, ferromagnetic and paramagnetic behavior at 5 K. Homogeneous distributions of Co and Ni ions in the particles observed by filter imaging analysis indicates that there is no evidence of Co or Ni metal throughout the powders