Hexacyano Ferrate (III) Reduction by Electron Transfer Induced by Plasmonic Catalysis on Gold Nanoparticles

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Plasmonic catalysis for the Suzuki–Miyaura cross-coupling reaction using palladium nanoflowers

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Gold(I)-Silver(I)-calix[8]arene complexes, precursors of bimetallic alloyed Au-Ag nanoparticles

International audienceIn this paper, we report the first synthesis and characterisations of bimetallic gold(I)–silver(I) calix[8]arene complexes. We show that the radiolytic reduction of these complexes leads to the formation of small bimetallic nanoparticles with an alloyed structure, as evidenced by XPS, HR-TEM and STEM/HAADF-EDX measurements

Polypyrrole nanostructures modified with mono- and bimetallic nanoparticles for photocatalytic H 2 generation

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A Facile One-Pot Synthesis of Versatile PEGylated Platinum Nanoflowers and Their Application in Radiation Therapy

International audienceNanomedicine has stepped into the spotlight of radiation therapy over the last two decades. Nanoparticles (NPs), especially metallic NPs, can potentiate radiotherapy by specific accumulation into tumors, thus enhancing the efficacy while alleviating the toxicity of radiotherapy. Water radiolysis is a simple, fast and environmentally-friendly method to prepare highly controllable metallic nanoparticles in large scale. In this study, we used this method to prepare biocompatible PEGylated (with Poly(Ethylene Glycol) diamine) platinum nanoflowers (Pt NFs). These nanoagents provide unique surface chemistry, which allows functionalization with various molecules such as fluorescent markers, drugs or radionuclides. The Pt NFs were produced with a controlled aggregation of small Pt subunits through a combination of grafted polymers and radiation-induced polymer cross-linking. Confocal microscopy and fluorescence lifetime imaging microscopy revealed that Pt NFs were localized in the cytoplasm of cervical cancer cells (HeLa) but not in the nucleus. Clonogenic assays revealed that Pt NFs amplify the gamma rays induced killing of HeLa cells with a sensitizing enhancement ratio (SER) of 23%, thus making them promising candidates for future cancer radiation therapy. Furthermore, the efficiency of Pt NFs to induce nanoscopic biomolecular damage by interacting with gamma rays, was evaluated using plasmids as molecular probe. These findings show that the Pt NFs are efficient nano-radio-enhancers. Finally, these NFs could be used to improve not only the performances of radiation therapy treatments but also drug delivery and/or diagnosis when functionalized with various molecules

Superior photocatalytic activity of polypyrrole nanostructures prepared by radiolysis in water and dichloromethane

International audienceConjugated polymers have emerged as very active photocatalysts under visible light. Among these materials, nanostructured polypyrrole (PPy) has recently been used as photocatalyst for degradation of environmental pollutants under UV as well as visible light. In the present study, we specifically explored the photocatalytic activity of conducting PPy synthesized by radiolysis, either in water (PPyH2O) or in dichloromethane solvent (PPyDCM), in the absence of any external dopant or template. The successful preparation of both kinds of conducting polymers was confirmed by complementary spectroscopic techniques and morphological characterizations. Besides, the photocatalytic activity of both materials was evaluated in the degradation of phenol as model pollutant in aqueous solution. PPyH2O as well as PPyDCM were found to exhibit remarkably high photocatalytic activity under both UV and visible light. These organic photocatalysts remain very stable after several cycles and thus, easily reusable. Interestingly, PPyDCM clearly appears as the most efficient photocatalyst due to its longer chain length, highly doped nature, lower optical band gap and extended absorption band from the UV to the near infrared region. The present work definitely validates radiation chemistry as an 2 alternative approach to synthesize conducting polymer-based photocatalysts. The obtained results also highlight that the radiosynthesized PPy, especially those prepared in dichloromethane, constitute promising candidates for photocatalytic depollution of water

Radio-Enhancing Properties of Bimetallic Au:Pt Nanoparticles: Experimental and Theoretical Evidence

International audienceThe use of nanoparticles, in combination with ionizing radiation, is considered a promising method to improve the performance of radiation therapies. In this work, we engineered mono-and bimetallic core-shell gold-platinum nanoparticles (NPs) grafted with poly (ethylene glycol) (PEG). Their radio-enhancing properties were investigated using plasmids as bio-nanomolecular probes and gamma radiation. We found that the presence of bimetallic Au:Pt-PEG NPs increased by 90% the induction of double-strand breaks, the signature of nanosize biodamage, and the most difficult cell lesion to repair. The radio-enhancement of Au:Pt-PEG NPs were found three times higher than that of Au-PEG NPs. This effect was scavenged by 80% in the presence of dimethyl sulfoxide, demonstrating the major role of hydroxyl radicals in the damage induction. Geant4-DNA Monte Carlo simulations were used to elucidate the physical processes involved in the radio-enhancement. We predicted enhancement factors of 40% and 45% for the induction of nanosize damage, respectively, for mono-and bimetallic nanoparticles, which is attributed to secondary electron impact processes. This work contributed to a better understanding of the interplay between energy deposition and the induction of nanosize biomolecular damage, being Monte Carlo simulations a simple method to guide the synthesis of new radio-enhancing agents

Green One-Step Synthesis of Medical Nanoagents for Advanced Radiation Therapy

Purpose: Metal-based nanoparticles (M-NPs) have attracted great attention in nanomedicine due to their capacity to amplify and improve the tumor targeting of medical beams. However, their simple, efficient, high-yield and reproducible production remains a challenge. Currently, M-NPs are mainly synthesized by chemical methods or radiolysis using toxic reactants. The waste of time, loss of material and potential environmental hazards are major limitations.Materials and Methods: This work proposes a simple, fast and green strategy to synthesize small, non-toxic and stable NPs in water with a 100% production rate. Ionizing radiation is used to simultaneously synthesize and sterilize the containing NPs solutions. The synthesis of platinum nanoparticles (Pt NPs) coated with biocompatible poly(ethylene glycol) ligands (PEG) is presented as proof of concept. The physicochemical properties of NPs were studied by complementary specialized techniques. Their toxicity and radio-enhancing properties were evaluated in a cancerous in vitro model. Using plasmid nanoprobes, we investigated the elementary mechanisms underpinning radio-enhancement.Results and Discussion: Pt NPs showed nearly spherical-like shapes and an average hydrodynamic diameter of 9 nm. NPs are zero-valent platinum successfully coated with PEG. They were found non-toxic and have the singular property of amplifying cell killing induced by γ-rays (14%) and even more, the effects of carbon ions (44%) used in particle therapy. They induce nanosized-molecular damage, which is a major finding to potentially implement this protocol in treatment planning simulations.Conclusion: This new eco-friendly, fast and simple proposed method opens a new era of engineering water-soluble biocompatible NPs and boosts the development of NP-aided radiation therapies