Search results for "Nanoparticle"
showing 10 items of 2198 documents
Reversible Cluster Formation of Colloidal Nanospheres by Interparticle Photodimerization
2004
Crosslinked spherical nanoparticles based on trimethoxysilane monomers have been prepared by polycondensation in aqueous emulsion. These particles have been labeled chemically at their surface region with two different types of organic dye molecules (cinnamate, coumarin), which both are well known for their ability to undergo a reversible photodimerization if irradiated with light of a suitable wavelength. Upon irradiation of dilute solutions of these nanoparticles with UV light, the photodimerization of labels belonging to different colloidal nanoparticles caused the formation of large colloidal clusters consisting of chemically bound individual nanospheres. This process has been quantitat…
Functionalization of Crosslinked Vesicles by Co-Self-Assembly of a Gelable Diblock Copolymer and Mercaptosilane
2008
Herein, a convenient and general method to simultaneously fix and functionalize polymeric vesicles with sulphydryl groups by the co-self-assembly of poly(ethylene oxide)-block-poly[3-(triethoxysilyl)propyl methacrylate] (PEO-b-PTESPMA) and 3-mercaptopropyltrialkoxysilane in an aqueous solution is reported. The presence of sulphydryl groups across the vesicle membrane has been confirmed by using an energy-filtered technique during TEM analysis and by capturing Au nanoparticles.
Synthesis of yttrium aluminum garnet nanoparticles in confined environment, and their characterization
2016
Abstract Nanopowders of yttrium aluminum garnet (YAG, Y3Al5O12) have been prepared by thermal treatment of hydroxides obtained by synthesis in a confined environment constituted by water/Cetyltrimethylammonium bromide (CTAB)/1-butanol/n-heptane. The phase behavior of the above system has been investigated on varying the water/CTAB molar ratio (R) at constant 1-butanol/CTAB and heptane/CTAB molar ratio. The dispersed aqueous phases were constituted by solutions of ammonia and of yttrium and aluminum nitrates, respectively. Measures of Kinematic Viscosity, Electrical Conductivity and Small Angle X-ray Scattering have been carried out. It was found that, on increasing the ammonia solution cont…
Structural Characterization of Zirconia Nanoparticles Prepared by Microwave-Hydrothermal Synthesis
2009
Nanocrystalline zirconia powders have been prepared by microwave-hydrothermal synthesis starting from aqueous solution of ZrOCl2·8H2O. Results of investigations on the aqueous suspension stability of the washed zirconia nanopowders by dynamic light scattering showed that the suspension, constituted by superaggregates of nanoparticles (131 ± 10 nm), was stable up to 15 days. Nanopowders were investigated by means of transmission electron microscopy and small angle x-ray scattering measurements which proved that the zirconia nanopowder is constituted by small primary nanoparticles of ca. 8 nm that agglomerate forming bigger aggregates of 50 ± 1 nm.
Water-Soluble Palladium Nanoparticles: Click Synthesis and Applications as a Recyclable Catalyst in Suzuki Cross-Couplings in Aqueous Media
2010
A new PEG-tagged material, which was prepared by a threefold copper-catalyzed [3+2] cycloaddition (click chemistry), was found to act as an efficient stabilizer for palladium nanoparticles. The newly formed material proved to be active as a recyclable catalyst in Suzuki coupling; the presence of polyether chains allowed for the catalytic runs to be conducted in aqueous media.
A Nanoparticulate Drug-Delivery System for Rivastigmine: Physico-Chemical and in vitro Biological Characterization
2007
The preparation and characterization of surface-PEGylated polymeric nanoparticles are described. These systems were obtained by UV irradiation of PHM and PHM-PEG 2000 as an inverse microemulsion, using an aqueous solution of the PHM/PHM-PEG 2000 copolymer mixture as the internal phase and triacetin saturated with water as the external phase, and characterized by dimensional analysis, zeta-potential measurements and XPS. in vitro biological tests demonstrated their cell compatibility and their ability to escape from phagocytosis. Rivastigmine was encapsulated into the nanoparticle structure and drug-release profiles from loaded samples were investigated in PBS at pH = 7.4 and human plasma.
Thermal and Chemical Stability of Thiol Bonding on Gold Nanostars
2015
The stability of thiol bonding on the surface of star-shaped gold nanoparticles was studied as a function of temperature in water and in a set of biologically relevant conditions. The stability was evaluated by monitoring the release of a model fluorescent dye, Bodipy-thiol (BDP-SH), from gold nanostars (GNSs) cocoated with poly(ethylene glycol) thiol (PEG-SH). The increase in the BDP-SH fluorescence emission, quenched when bound to the GNSs, was exploited to this purpose. A maximum 15% dye release in aqueous solution was found when the bulk temperature of gold nanostars solutions was increased to T = 42 °C, the maximum physiological temperature. This fraction reduces 3-5% for temperatures …
Consolidation and protection by nanolime: recent advances for the conservation of the graffiti, Carceri dello Steri Palermo and of the 18th century l…
2014
Abstract Nanolime dispersed in 2-propanol was extensively used for the consolidation of wall paintings. The knowledge of the advances of this methodology dealing with all the possible effects associated with the nanolime new material in conservation is fundamental to assess and improve the technique. In this paper, four different dispersions of Ca(OH) 2 nanoparticles were characterised by Small Angle X-rays Scattering technique (SAXS) and Transmission Electron Microscopy (TEM) in order to achieve information on size, shape, polydispersity, agglomeration, and crystal structure (by SAED patterns) of the particles. Once characterised, the dispersions were tested in two different case studies, …
Fluorogenic detection of Tetryl and TNT explosives using nanoscopic-capped mesoporous hybrid materials
2013
[EN] A hybrid capped mesoporous material, which was selectively opened in the presence of Tetryl and TNT, has been synthesised and used for the fluorogenic recognition of these nitroaromatic explosives.
Vibronic structures in the visible luminescence of silica nanoparticles
2014
Time resolved photoluminescence investigation in air and in vacuum atmosphere of the visible luminescence related to silica surface defects is here reported. Two contributions can be singled out: one, observed both in air and in vacuum, is the well-known blue band, peaked around 2.8 eV decaying in ∼5 ns; the other, only observed in vacuum, is a structured emission in the violet range characterized by two vibronic progressions spaced 1370 cm−1 and 360 cm−1 decaying in ∼100 ns. In contrast with previous attribution, the well distinguishable spectroscopic properties together with the observation of the effects induced by the interaction with nitrogen allow to state that the emission bands orig…