Search results for "nanoparticle"

Effect of Pre-Reduction on the Properties and the Catalytic Activity of Pd/Carbon Catalysts: A Comparison with Pd/Al2O3

2013

The effect of pre-reduction in solution with chemical reagents on the catalytic performance and catalyst properties of Pd/carbon catalysts was systematically investigated with a multitechnique approach. The results are critically discussed in comparison to those recently obtained on analogous Pd/alumina catalysts. It was proved that the Pd phase on the carbon surface is characterized by a high mobility, opposite to what occurs on alumina. As a result, the Pd particles on carbon aggregate together during pre-reduction, with a consequent decrease in available metal surface. Pd particles remain aggregated also in reaction conditions; the decreased Pd dispersion negatively affects the catalyst …

MODIFICA SUPERFICIALE DI FILM DI POLY(ETILENE-co-ACIDO ACRILICO) CON NANOPARTICELLE DI SILICE ATTIVATA

2009

Biologically-induced transition of bio-silica sol to mesoscopic gelatinous flocs: a biomimetic approach to a controlled fabrication of bio-silica str…

2012

Siliceous sponges form their skeletal elements, the spicules, enzymatically via the sponge-specific enzyme silicatein. The enzymatic product of silicatein in vitro is a bio-silica polymer that is not processed/hardened by phase separation. In the present study we applied a two-phase system to investigate the transition of bio-silica, formed by silicatein, from the lucid state to the opaque/turbid state. We report for the first time that the polyether polyethylene glycol [PEG] causes a rapid transition of the lucid bio-silica to the opaque/turbid state. For the experiments the recombinant silicatein from the demosponge Suberites domuncula had been used. This process is rapid (1 h) and procee…

Peptide-Capped Mesoporous Nanoparticles: Toward a more Efficient Internalization of Alendronate

2020

[EN] Osteoporosis is an illness which appears when the osteoblast/osteoclast activities are unbalanced taking place bone resorption (caused by osteoclasts) in higher extension than bone formation (induced by osteoblasts). Alendronate is one of the most used drugs for osteoporosis treatment despite its scarce bioavailability. Here we present the synthesis and characterization of mesoporous gated nanoparticles (two sets) for the controlled release of alendronate. The first set of nanoparticles (S1) were loaded with sulforhodamine B and capped with a peptide that could be selectively hydrolyzed by cathepsin K enzyme (overexpressed in osteoclasts). The second set (S2) was functionalized with am…

Preparation and characterisation of Na 2 S and ZnSO 4 nanoparticles in water/sodium bis(2-ethylhexyl)sulphosuccinate/ n -heptane microemulsions

2001

The preparation procedure for nanoparticles of the water-soluble salts Na2S and ZnSO4, two commonly used reagents to synthesise ZnS nanoparticles, by evaporation of volatile components of salt-containing water-in-oil microemulsions is described. In suitable conditions, the evaporation leads to the formation of dry salt–surfactant composites and to the formation of Na2S or ZnSO4 nanoparticles. It was found that the salt–surfactant composites can be totally redissolved in a dry apolar organic solvent allowing the formation of virtually water-free solutions containing a considerable amount of the water-soluble salts. The presence of nanoparticles in these solutions and in the composites has be…

Controlled UV-C light-induced fusion of thiol-passivated gold nanoparticles.

2011

Thiol-passivated gold nanoparticles (AuNPs) of a relatively small size, either decorated with chromophoric groups, such as a phthalimide (Au@PH) and benzophenone (Au@BP), or capped with octadecanethiol (Au@ODCN) have been synthesized and characterized by NMR and UV-vis spectroscopy as well as transmission electron microscopy (TEM). These NPs were irradiated in chloroform at different UV-wavelengths using either a nanosecond laser (266 and 355 nm, ca. 12 mJ/pulse, 10 ns pulse) or conventional lamps (300 nmλ400 nm and ca. 240 nmλ280 nm) and the new AuNPs were characterized by X-ray and UV-vis spectroscopy, as well as by TEM. Laser irradiation at 355 nm led to NP aggregation and precipitation,…

CTAB‐PLGA Curcumin Nanoparticles: Preparation, Biophysical Characterization and Their Enhanced Antifungal Activity against Phytopathogenic Fungus Pyt…

2020

Role of pH in the synthesis and growth of gold nanoparticles using L-asparagine: a combined experimental and simulation study

2020

Abstract The use of biomolecules as capping and reducing agents in the synthesis of metallic nanoparticles constitutes a promising framework to achieve desired functional properties with minimal toxicity. The system’s complexity and the large number of variables involved represent a challenge for theoretical and experimental investigations aiming at devising precise synthesis protocols. In this work, we use L-asparagine (Asn), an amino acid building block of large biomolecular systems, to synthesise gold nanoparticles (AuNPs) in aqueous solution at controlled pH. The use of Asn offers a primary system that allows us to understand the role of biomolecules in synthesising metallic nanoparticl…

Characterization of transparent silver loaded poly(l-lactide) films produced by melt-compounding for the sustained release of antimicrobial silver io…

2014

Abstract In the present study, thermally stable silver complexes were produced and incorporated into a poly-( l -lactide) (PLA) matrix by melt-compounding. The effect of the different formulations on the mechanical and color properties was first evaluated. Additionally, the release of silver ions to an aqueous environment was also monitored over time by anodic stripping voltammetry and correlated with the antimicrobial performance against Salmonella enterica. The incorporation of some silver compounds with contents of 1 wt% did not affect the mechanical or optical properties of the films. The films showed a good potential for application in surface treatment and demonstrated a sustainable, …

A Facile Approach for Transferring Hydrophobic Magnetic Nanoparticles into Water-Soluble Particles

2008

A novel, easy and high-efficient method is described for transferring hydrophobic magnetic Fe 3 O 4 nanoparticles from organic to aqueous solution by wrapping a thermo-responsive and photocrosslinkable poly(N-isopropylacrylamide) (PNIPAm) terpolymer around the particles. The wrapping procedure is introduced by the co-nonsolvent transition of PNIPAm in the mixing solvent and the polymer can dissolve in water carrying Fe 3 O 4 nanoparticles by noncovalent interaction. The temperature-dependant and magnetic properties of the water-soluble particles are characterized in this paper.