Synthèse et caractérisation de nanoparticules métalliques vers la nanomédecine

L'objectif essentiel de notre travail a consisté à synthétiser des nanoparticules d'or monodisperses, stables en conditions physiologiques et des nanoparticules hybrides type Au@MO (où MO = Fe3O4 ou ZnO) pour des applications biomédicales, en magnétoplasmon ou en photocatalyse. La stratégie adoptée est fondée sur l'utilisation du procédé polyol comme méthode de synthèse par chimie douce. L'étude des propriétés optiques des nanoparticules élaborées a été réalisée essentiellement par spectroscopie de diffusion Raman. Dans un premier lieu, nous avons préparé des nanotriangles d'or stabilisées par le polyvinylpyrrolidone (PVP), ceci en contrôlant plusieurs paramètres de synthèse à savoir le rapport PVP/AuIII, la température et la nature du surfactant. Par la suite, nous avons étudié leurs propriétés plasmoniques et de diffusion Raman exaltée de surface ce qui nous a permis d'éclairer la dynamique des interactions PVP-Au. Les mesures préliminaires d'hyperthermie sur des particules d'or de 100 nm montrent un pouvoir chauffant intéressant. La deuxième partie de notre travail a été consacré à la synthétise de nanoparticules hybrides Au-Fe3O4 en adoptant la stratégie "one pot". Les expériences Raman-SERS révèlent la structure fine de ces particules. Une étude Raman-SERS de la transition de la phase magnétite (Fe3O4) en hématite (a-Fe2O3) est détaillée. La dernière partie de ce travail est consacrée à la synthèse des nanoparticules hybrides Au-ZnO par la stratégie "one pot". Les propriétés plasmoniques sont étudiées par spectroscopie d'absorption et sont soutenues par des simulations numériques. Les particules élaborées présentent une forte résonance plasmonique qui peut être intéressante pour des applications photocatalytiques.The main objective of our work was to synthesize monodisperse gold nanoparticles, stable under physiological conditions and hybrid nanoparticles such as Au@MO (where MO = ZnO or Fe3O4) for biomedical applications, magnétoplasmon or photocatalysis. The strategy is based on using the polyol process as a method of synthesis by soft chemistry. The study of the optical properties of nanoparticles was performed essentially by Raman spectroscopy. Firstly, we have prepared single-crystalline triangular gold nanoplates (Tr-AuNPs) with well-defined shape and tunable size by polyvinylpyrrolidone (PVP) by controlling several parameters (the molar ratio of PVP to AuIII, temperature and the nature of the surfactant). Thereafter, we studied their properties and plasmon-enhanced Raman scattering surface which allowed us to clarify the dynamics of interactions PVP-Au. Preliminary hyperthermia mesearement on gold nanoparticles of 100 nm show an interesting heating power. The second part of our work, we have reported the synthesis of hybrid Au-Fe3O4 nanoparticles using a novel one-pot process, and have studied their plasmonic and SERS related properties as well as their phase transition properties. By combining SERS experiments and numerical simulations of the plasmonic near fields, we were able to investigate the fine structure of the Fe3O4 shell. By changing the laser intensity, we have investigated the transformation of the magnetite Fe3O4 shell into maghemite and hematite (a-Fe2O3). The last part of this work is devoted to the synthesis of hybrid Au-ZnO nanoparticles with a narrow size distribution, a controlled morphology and a high crystalline quality using the one pot polyol process, without adding any other reagents, template or complex metal ligand. Optical extinction measurements combined with numerical simulations showed that the Au-ZnO nanoparticles exhibit a localized surface plasmon resonance (SPR) clearly red shifted with respect to that of bare Au nanoparticles (AuNPs)

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

Synthèse et caractérisation de nanoparticules métalliques vers la nanomédecine

TOULOUSE3-BU Sciences (315552104) / SudocSudocFranceF

Synthesis of hybrid Au-ZnO nanoparticles using a one pot polyol process

cited By 7International audienceIn this work, we report on the synthesis of hybrid Au-ZnO nanoparticles using a one-pot chemical method that makes use of 1,3-propanediol as a solvent, a reducing agent and a stabilizing layer. The produced nanoparticles consisted of Au cores decorated with ZnO nanoparticles. The structure and morphology of the nanoparticles were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), energy dispersive X-ray spectrometry (EDX) and Raman spectroscopy. Optical extinction measurements, combined with numerical simulations, showed that the Au-ZnO nanoparticles exhibit a localized surface plasmon resonance (SPR) clearly red-shifted with respect to that of bare Au nanoparticles (AuNPs). This work contributes to the emergence of multi-functional nanomaterials with possible applications in surface plasmon resonance based biosensors, energy-conversion devices, and in water-splitting hydrogen production

Effect of Plasmonic Gold Nanoprisms on Biofilm Formation and Heat Shock Proteins Expression in Human Pathogenic Bacteria

Gold nanoparticles have gained interest in biomedical sciences in the areas of nano-diagnostics, bio-labeling, drug delivery, and bacterial infection. In this study, we examined, for the first time, the antibacterial and antibiofilm properties of plasmonic gold nanoprisms against human pathogenic bacteria using MIC and crystal violet. In addition, the expression level of GroEL/GroES heat shock proteins was also investigated by western blot. Gold nanoparticles were characterized by TEM and EDX, which showed equilateral triangular prisms with an average edge length of 150 nm. Antibacterial activity testing showed a great effect of AuNPs against pathogenic bacteria with MICs values ranging from 50 μg/mL to 100 μg/mL. Nanoparticles demonstrated strong biofilm inhibition action with a percentage of inhibition ranging from 40.44 to 82.43%. Western blot analysis revealed that GroEL was an AuNPs-inducible protein with an increase of up to 66.04%, but GroES was down-regulated with a reduction of up to 46.81%. Accordingly, plasmonic gold nanoprisms, could be a good candidate for antibiotics substitution in order to treat bacterial infections

Construction of a Novel Three-Dimensional PEDOT/RVC Electrode Structure for Capacitive Deionization: Testing and Performance

This article discusses the deposition of different amount of microstuctured poly(3,4-ethylenedioxythiophene) (PEDOT) on reticulated vitreous carbon (RVC) by electrochemical method to prepare three-dimensional (3D) PEDOT/RVC electrodes aimed to be used in capacitive deionization (CDI) technology. A CDI unit cell has been constructed here in this study. The performance of CDI cell in the ion removal of NaCl onto the sites of PEDOT/RVC electrode has been systematically investigated in terms of flow-rate, applied electrical voltage, and increasing PEDOT loading on PEDOT/RVC electrodes. It is observed that the increase in flow-rate, electric voltage, and PEDOT loading up to a certain level improve the ion removal performance of electrode in the CDI cell. The result shows that these electrodes can be used effectively for desalination technology, as the electrosorption capacity/desalination performance of these electrodes is quite high compared to carbon materials. Moreover, the stability of the electrodes has been tested and it is reported that these electrodes are regenerative. The effect of increasing NaCl concentration on the electrosorption capacity has also been investigated for these electrodes. Finally, it has been shown that 1 m3 PEDOT-120 min/RVC electrodes from 75 mg/L NaCl feed solution produce 421, 978 L water per day of 20 mg/L NaCl final concentration

Toxicity of silver nanoparticles on the clam Ruditapes decussatus assessed through biomarkers and clearance rate

The current bioassay aims the evaluation of the ecotoxicity of the silver nanoparticles (NPs) (100 and 200 μ g l ^−1 ) on Ruditapes decussatus after 48 h and 7 days of its exposure. The biochemical analyses performed at gills and digestive glands showed a disturbance of the antioxidant system following the exposure of clams to Ag NPs. The catalase activity was induced and varied significantly depending on the concentration of Ag NPs and the exposure time, as well as the organ analysed. Simultaneousely, a decrease in Gluthation S -Transferase activity was observed at all concentrations tested and organs considered. The acetylcholinesterase activity results confirmed that the threshold of Ag NPs able to disrupt the the cholinergic system was less than 100 μ g l ^−1 . In overall, silver nanoparticles had a significant caused antagonistic effect on clams in both oxidative- and cholinergic states. Furthermore the findings obtained in this study demonstrated that Ruditapes decussatus can employed as a potential bioindicative species in the assessment of the toxicity of such an emerging material as Ag NPs