Search results for "nanoparticle"

Ligand-Protected Gold Nanoclusters as Superatoms—Insights from Theory and Computations

2012

Abstract Gold clusters and nanoparticles, stabilized by various ligands, exhibit a rich array of interesting and important electronic, optical, chemical and catalytic properties. Many particles can now be synthesized by wet chemistry, and they can be handled as normal chemicals: stored, modified and functionalized for applications in medical therapy, biolabelling, sensing, nanoelectronics and catalysis. In recent years, understanding of the stability, surface chemistry and functionalization of these interesting building blocks of nano-matter has taken a quantum leap. This is facilitated by simultaneous breakthroughs in experimental and theoretical fronts concerning accurate structural deter…

Radiation Engineering of Multifunctional Nanogels

2016

Nanogels combine the favourable properties of hydrogels with those of colloids. They can be soft and conformable, stimuli-responsive and highly permeable, and can expose a large surface with functional groups for conjugation to small and large molecules, and even macromolecules. They are among the very few systems that can be generated and used as aqueous dispersions. Nanogels are emerging materials for targeted drug delivery and bio-imaging, but they have also shown potential for water purification and in catalysis. The possibility of manufacturing nanogels with a simple process and at relatively low cost is a key criterion for their continued development and successful application. This p…

Elaboration of functionalized nanoparticles : applications as MRI contrast agent

2010

Spinel structured iron oxide nanoparticles open the way of biomedical applications of nanomaterials.Superparamagnetic properties of ten nanometer size crystallites permit to use them in diagnosis such as Magnetic Resonance Imaging (MRI).The aim of this work was to synthesize colloidal suspension of magnetite or maghemite (called USPIO for Ultrasmall SuperParamagnetic Iron Oxide) stable in physiological conditions (pH = 7.4 and [NaCl] = 0.15M).By classical co-precipitation method, UPSIO were synthesized with a mean crystallite size of 8 nm, with a specific surface area of 110 m².g-1 and an aggregate size of 20 nm. To stabilize these nano-objects, two ways were investigated. Electrostatic age…

Nanoscale Deposition of Single-Molecule Magnets onto SiO2 Patterns

2007

bet on a silicon oxide template while the rest ofthe macroscopic surface remains free of molecules. Local oxi-dation was used to fabricate silicon oxide nanopatterns, eitherdots or stripes, over a Si (100) surface coated with a SAM.Their width ranged from 30 to 500 nm whereas the lengthcould be modified from a few nanometers up to several mi-crometers. Nanoscale direct assembly arose from a combina-tion of three factors: i) the strength of the attractive electro-static interactions between the molecules and the local oxides;ii) the weak repulsive interaction between the molecules andthe unpatternedsurface; and iii) the size of the nanopattern.Local oxidation nanolithography (LON) allows the…

Biogenic iron-silver nanoparticles inhibit bacterial biofilm formation due to Ag+ release as determined by a novel phycoerythrin-based assay

2020

Silver nanoparticles (Ag-NPs) can be considered as a cost-effective alternative to antibiotics. In the presence of Fe(III)-citrate and Ag+, Klebsiella oxytoca DSM 29614 produces biogenic Ag-NPs embedded in its peculiar exopolysaccharide (EPS). K. oxytoca DSM 29614 was cultivated in a defined growth medium–containing citrate (as sole carbon source) and supplemented with Ag+ and either low or high Fe(III) concentration. As inferred from elemental analysis, transmission and scanning electron microscopy, Fourier transform infrared spectrometry and dynamic light scattering, Ag-EPS NPs were produced in both conditions and contained also Fe. The production yield of high-Fe/Ag-EPS NPs was 12 times …

GraftFast Surface Engineering to Improve MOF Nanoparticles Furtiveness

2018

International audience; Controlling the outer surface of nanometric metal–organic frameworks (nanoMOFs) and further understanding the in vivo effect of the coated material are crucial for the convenient biomedical applications of MOFs. However, in most studies, the surface modification protocol is often associated with significant toxicity and/or lack of selectivity. As an alternative, how the highly selective and general grafting GraftFast method leads, through a green and simple process, to the successful attachment of multifunctional biopolymers (polyethylene glycol (PEG) and hyaluronic acid) on the external surface of nanoMOFs is reported. In particular, effectively PEGylated iron trime…

dsRNA-functionalized multifunctional gamma-Fe2O3 nanocrystals: a tool for targeting cell surface receptors.

2008

Gold nanoparticle catalysis of the cis-trans isomerization of azobenzene

2013

Ablated, “pseudo-naked” gold nanoparticles (AuNPs) catalyze the cis–trans isomerization of substituted azobenzenes. para-Substitution was found to affect the rate of isomerization, suggesting the participation of AuNP-mediated electron transfer in the isomerization mechanism. Fil: Hallet Tapley, Geniece. University of Ottawa; Canadá Fil: D'Alfonso, Claudio. University of Ottawa; Canadá. Universita Di Roma; Italia Fil: Pacioni, Natalia Lorena. University of Ottawa; Canadá Fil: McTiernan, Cristopher D.. University of Ottawa; Canadá Fil: Gonzalez Bejar, Maria. University of Ottawa; Canadá. Universidad de Valencia; España Fil: Lanzalunga, Osvaldo. Universita Di Roma; Italia Fil: Alarcon, Emilio…

Charge transfer effects on the chemical reactivity of PdxCu1−xnanoalloys

2015

This work reports on the synthesis and characterization of PdxCu1-x (x = 0.7, 0.5 and 0.3) nanoalloys obtained via an eco-friendly chemical reduction method based on ascorbic acid and trisodium citrate. The average size of the quasi-spherical nanoparticles (NPs) obtained by this method was about 4 nm, as observed by TEM. The colloids containing different NPs were then supported on carbon in order to produce powder samples (PdxCu1-x/C) whose electronic and structural properties were probed by different techniques. XRD analysis indicated the formation of crystalline PdCu alloys with a nanoscaled crystallite size. Core-level XPS results provided a fingerprint of a charge transfer process betwe…

Synergistic Activity of Silver Nanoparticles and Polyaminocyclodextrins in Nanosponge Architectures

2019

Four new composite materials, formed by silver nanoparticles embedded in polyamino-cyclodextrin nanosponge architectures, were designed exploiting the affinity of polyamino-cyclodextrins towards Ag+ ions. These materials were characterized by means of different techniques (thermogravimetry, FT-IR, solid state NMR, SEM, HR-TEM), and tested as catalysts for the reduction of nitroarenes and the oxidative coupling of anilines. The results obtained showed synergistic activity between the supramolecular binding abilities of the nanosponge matrix and the catalytic properties of the metal nanoparticle, and open the way towards the design of new composite smart nanomaterials with improved catalytic …