One-Pot Synthesis of Cationic Gold Nanoparticles by Differential Reduction

The size-controlled synthesis of cationic particles by differential reduction of HAuCl precursor in the presence of NaBH and 1-aminoundecane-12-thiol (AUT) is reported. The number of seed particles is determined by the fraction of the initially Au precursor reduced by NaBH present in the reaction mixture, which are then grown larger by the AUT, acting as both weak reducing agent and stabilizing surfactant. By this methodology, size controlled synthesis is achieved in a two-step one-pot synthesis at room temperature

Changes in Caco-2 cells transcriptome profiles upon exposure to gold nanoparticles

Abstract Higher efficacy and safety of nano gold therapeutics require examination of cellular responses to gold nanoparticles (AuNPs). In this work we compared cellular uptake, cytotoxicity and RNA expression patterns induced in Caco-2 cells exposed to AuNP (5 and 30 nm). Cellular internalization was dose and time-dependent for both AuNPs. The toxicity was observed by colony forming efficiency (CFE) and not by Trypan blue assay, and exclusively for 5 nm AuNPs, starting at the concentration of 200 μM (24 and 72 h of exposure). The most pronounced changes in gene expression (Agilent microarrays) were detected at 72 h (300 μM) of exposure to AuNPs (5 nm). The biological processes affected by smaller AuNPs were: RNA/zinc ion/transition metal ion binding (decreased), cadmium/copper ion binding and glutathione metabolism (increased). Some Nrf2 responsive genes (several metallothioneins, HMOX, G6PD, OSGIN1 and GPX2) were highly up regulated. Members of the selenoproteins were also differentially expressed. Our findings indicate that exposure to high concentration of AuNPs (5 nm) induces metal exposure, oxidative stress signaling pathways, and might influence selenium homeostasis. Some of detected cellular responses might be explored as potential enhancers of anti-cancer properties of AuNPs based nanomedicines

Rational design of multi-functional gold nanoparticles with controlled biomolecule adsorption: a multi-method approach for in-depth characterization

Multi-functionalized nanoparticles are of great interest for diagnostic and therapeutic applications

A high throughput imaging database of toxicological effects of nanomaterials tested on HepaRG cells

The large amount of existing nanomaterials demands rapid and reliable methods for testing their potential toxicological effect on human health, preferably by means of relevant in vitro techniques in order to reduce testing on animals. Combining high throughput workflows with automated high content imaging techniques allows deriving much more information from cell-based assays than the typical readouts (i.e. one measurement per well) with optical plate-readers. We present here a dataset including data based on a maximum of 14 different read outs (including viable cell count, cell membrane permeability, apoptotic cell death, mitochondrial membrane potential and steatosis) of the human hepatoma HepaRG cell line treated with a large set of nanomaterials, coatings and supernatants at different concentrations. The database, given its size, can be utilized in the development of in silico hazard assessment and prediction tools or can be combined with toxicity results from other in vitro test systems.peer-reviewe

Structuration and integration of magnetic nanoparticles on surfaces and devices

Different experimental approaches used for structuration of magnetic nanoparticles on surfaces are reviewed. Nanoparticles tend to organize on surfaces through self-assembly mechanisms controlled by non-covalent interactions which are modulated by their shape, size and morphology as well as by other external parameters such as the nature of the solvent or the capping layer. Further control on the structuration can be achieved by the use of external magnetic fields or other structuring techniques, mainly lithographic or atomic force microscopy (AFM)-based techniques. Moreover, results can be improved by chemical functionalization or the use of biological templates. Chemical functionalization of the nanoparticles and/or the surface ensures a proper stability as well as control of the formation of a (sub)monolayer. On the other hand, the use of biological templates facilitates the structuration of several families of nanoparticles, which otherwise may be difficult to form, simply by establishing the experimental conditions required for the structuration of the organic capsule. All these experimental efforts are directed ultimately to the integration of magnetic nanoparticles in sensors which constitute the future generation of hybrid magnetic devices. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.We thank the Spanish government for the project MAT2009-13977-C03-03. N.D and E.B. thank the Spanish government for a Ramon y Cajal and an F.P.I. grant, respectively.Peer Reviewe

Small Gold Nanoparticles Synthesized with Sodium Citrate and Heavy Water: Insights into the Reaction Mechanism

5 páginas, 3 figuras, 1 esquema.The effect of solvent isotopic replacement (H for D) on the size of gold nanoparticles (Au NPs) prepared by sodium citrate reduction has been investigated. With increasing replacement of water by deuterium oxide, smaller sizes of Au NPs are obtained, which is interpreted as a consequence of a faster reduction. A mechanism in which a substitution complex, [AuCl3(C6H5O7)−2]−, is formed from AuCl4 and citrate ions prior to its rate-limiting disproportionation into products is suggested. This novel procedure offers an attractive alternative to the existing ones and opens a full range of possibilities for biological studies.The work is supported in part by Ministerio de Ciencia e Innovación under grant numbers PTQ-06-2-0839 (for I.O.-J.) and Consolider Nanobiomed Ingenio 2010.Peer reviewe

Exploring the Limitations of the Use of Competing Reducers to Control the Morphology and Composition of Pt and PtCo Nanocrystals

10 páginas, 9 figuras, 2 tablas.We have explored size- and shape-controlled synthesis of platinum nanocrystals (Pt NCs) by systematically comparing the differential reducing performance of two competing reducing agents in a one-pot synthesis: hexadecanediol, a weak reducer, and metallic cobalt or superhydride, stronger reducers of Pt. In addition to its role as a metal reducer, Co also functions as a shape-directing agent and is incorporated into the Pt NCs, forming a PtCo alloy structure. By maintaining a constant HDD concentration and systematically increasing the Co content, the shape of the resulting NCs was found to alter from polypods, when no Co was present, to cuboctahedrons and cubes when trace amounts of Co were added, and back to polypods when Co dominated the reduction process. On the other hand, when the concentration of HDD was systematically increased (with Co kept constant), evolution from polypod morphology to prismatic/spherical/cubic NCs, followed by irregular shapes was observed. Both experimental results indicate the importance of the competitive role between the reducing agents, their concentration limits for achieving a controlled morphology, and the presence of Co as a shape-directing agent to alter the NC shape. This allows the exploration of a wide range of NC morphologies without significant modification of the synthesis recipe.This work is supported by the Spanish MICINN. S.L. acknowledges the support of the Beatriu de Pinós fellowship from the Catalan Government. M.V. acknowledges the support from project: MAT2006-13572- C02-02.Peer reviewe

Pt nanocrystal evolution in the presence of Au(III)-salts at room temperature: spontaneous formation of AuPt heterodimers

6 páginas, 5 figuras.-- El pdf del artículo es el manuscrito de autor.Room temperature synthesis of AuPt heterodimers is reported using a simple protocol. The role of oleylamine and Pt NCs in the reduction and nucleation of Au has been investigated. There are two unique aspects in this synthesis. Firstly, the synthesis was conducted at room temperature, which enabled the heterodimer growth to progress at a slower rate and thus allowed monitoring of the Au nucleation process. Secondly, these conditions allowed epitaxial growth with no crystal modification at the Au–Pt interphase. The presence of Pt NC seeds markedly accelerated the reaction, serving both as nucleation platforms and as an initial catalytic reducer of the Au ions in solution. The growth of Au on Pt NCs was monitored at different times by UV-vis, HRTEM and XRD.This work was supported by the Spanish MICINN. S.L. thanks the Catalan Gov. for a B.P. grant, and M.V. for the support from project: MAT2006-13572-C02-02.Peer reviewe

Synthesis of Platinum Cubes, Polypods, Cuboctahedrons, and Raspberries Assisted by Cobalt Nanocrystals

10 páginas, 10 figuras, 1 tabla, 1 esquema.The introduction of metallic traces into the synthesis of platinum nanocrystals (Pt NCs) has been investigated as a surfactant-independent means of controlling shape. Various nanocrystal morphologies have been produced without modification of the reaction conditions, composition, and concentration other than the presence of cobalt traces (<5%). In the presence of metallic cobalt (a strong reducer for Pt cations) cubic Pt NCs are obtained, while cobalt ions or gold NCs have no effect on the synthesis, and as a result, polypods are obtained. Intermediate shapes such as cemented cubes or cuboctahedron NCs are also obtained under similar conditions. Thus, various NC shapes can be obtained with subtle changes, which illustrates the high susceptibility and mutability of the NC shape to modification of the reaction kinetics during the early reduction process. Our studies help progress toward a general mechanism for nanocrystal shape control.The work is supported by the Spanish MICIN. S.L. acknowledges the support from a Beatriu de Pinós fellowship from the Catalan Government.Peer reviewe