1,721,289 research outputs found
Gold nanoparticles stabilised by GGC peptide terminated with a RDG motif
No full textGold nanoparticles stabilized by nucleobases, nucleosides and nucleotides
S. Avvakumova, Milano/I, F. Porta, Milano/I, G. Scari, Milano/I
Dr. Svetlana Avvakumova, University of Milan, Dip. Chimica Inorganica Metall. Anal., L. Malatesta, Via Venezian 21, 20133 Milano, Italy
Today gold nanoparticles (AuNPs) have become an important biomedical tool in cancer research. The presence of a negative charge on the surface of AuNPs helps to modify the surface of AuNPs by binding with several biomolecules. It is well established that capped AuNPs are biocompatible and non-toxic allowing their use in cancer treatment [1]. Nucleobases, nucleosides and nucleotides, used in this work, were among the first chemotherapeutic agents introduced for the medical treatment of cancer. These agents behave as antimetabolites and interact with a large number of intracellular targets. Biocompatible gold nanoparticles have been synthesized by reduction of NaAuCl4 aqueous solution by sodium borohydride as reducing agent. Adenine, adenosine, guanine, guanosine, cytosine, cytidine, thymine, guanosine 5’- monophosphate and cytidine 5’-monophosphate were used as stabilising agents. Au:stabiliser:NaBH4 molar ratios have been set up for obtaining red stable sols constituted by spherical gold nanoparticles with mean diameters in the 2-10 nm range. Reaction course was followed by UV-vis spectroscopy for studying the kinetic of reaction and plasmon peaks were found in the range of 513-530 nm. The colloids obtained were characterized by spectroscopic, microscopic and crystallographic methods (1H NMR, ATR-FTIR, XRD and TEM) studying the ligand interaction with the surface of gold nanoparticles. ATR-FTIR and 1H-NMR studies highlighted that the binding of ligands with the metallic surface dipends on the structure of molecules (nucleobases, nucleosides or nucleotides).
Literature:
[1] C. M. Galmarini, J. R. Mackey, C. Dumontet, The Lancet Oncology, 2002, Vol 3, p. 415
Gold nanoparticles stabilised by nucleobases, nucleosides and nucleotides
No full textGold nanoparticles stabilized by nucleobases, nucleosides and nucleotides
S. Avvakumova, Milano/I, F. Porta, Milano/I, G. Scari, Milano/I
Dr. Svetlana Avvakumova, University of Milan, Dip. Chimica Inorganica Metall. Anal., L. Malatesta, Via Venezian 21, 20133 Milano, Italy
Today gold nanoparticles (AuNPs) have become an important biomedical tool in cancer research. The presence of a negative charge on the surface of AuNPs helps to modify the surface of AuNPs by binding with several biomolecules. It is well established that capped AuNPs are biocompatible and non-toxic allowing their use in cancer treatment [1]. Nucleobases, nucleosides and nucleotides, used in this work, were among the first chemotherapeutic agents introduced for the medical treatment of cancer. These agents behave as antimetabolites and interact with a large number of intracellular targets. Biocompatible gold nanoparticles have been synthesized by reduction of NaAuCl4 aqueous solution by sodium borohydride as reducing agent. Adenine, adenosine, guanine, guanosine, cytosine, cytidine, thymine, guanosine 5’- monophosphate and cytidine 5’-monophosphate were used as stabilising agents. Au:stabiliser:NaBH4 molar ratios have been set up for obtaining red stable sols constituted by spherical gold nanoparticles with mean diameters in the 2-10 nm range. Reaction course was followed by UV-vis spectroscopy for studying the kinetic of reaction and plasmon peaks were found in the range of 513-530 nm. The colloids obtained were characterized by spectroscopic, microscopic and crystallographic methods (1H NMR, ATR-FTIR, XRD and TEM) studying the ligand interaction with the surface of gold nanoparticles. ATR-FTIR and 1H-NMR studies highlighted that the binding of ligands with the metallic surface dipends on the structure of molecules (nucleobases, nucleosides or nucleotides).
Literature:
[1] C. M. Galmarini, J. R. Mackey, C. Dumontet, The Lancet Oncology, 2002, Vol 3, p. 415
Catalytic synthesis of C-nitroso compounds by cis-Mo(O)(2)(acac)(2)
No full textThe ortho, meta and para mono substituted anilines R-C6H4NH2 (R = 4-Me, 3-Me, 2-Me, 4-Et, 2-Et, 4-Br, 3-Br 2-Br; 4-Cl, 3-Cl, 2-Cl,4-F, 4-Pr-i, 4-Bu-t) were catalytically oxidised by H2O2, in the presence of cis-Mo(O)(2)(acac)(2), (acacH = CH3C(O)CH2C(O)CH3), producing the corresponding C-nitroso derivatives, R-C6H4NO. High conversions and selectivities were obtained. (C) 2000 Elsevier Science B.V. 2000 rights reserved
pre-formed gold particle immobilized on supports: preparation and catalytic applications
No full textOxidation of alcohols and sugars using Au/C catalysts - Part 1. Alcohols
No full textThe activity of Au/C catalysts has been reviewed in the liquid phase oxidation of alcohols as a function of preparation method, particle size and dispersion, surface exposure and nature of the support. A strong influence of substrate structure has also been observed. Monometallic Au on carbon catalysts show a unique behaviour in the liquid phase oxidation of alcohols compared with Pt- and Pd-based systems, characterised by a higher resistance to poisoning from both oxygen and (by)products normally affecting other catalysts. (c) 2005 Elsevier B.V. All rights reserved
Selective oxidation of glycerol to sodium glycerate with gold on carbon catalyst: an insight into reaction selectivity
No full textGlycerol was oxidised with oxygen in the presence of gold on carbon as the catalyst. Two types of catalysts were identified: one, characterised by well-dispersed nanoparticles with a mean diameter centred at 6 nm, did not maintain the initial selectivity of the oxidation at full
conversion; the other, characterised by larger particles (> 20 nm), showed constant selectivity from the beginning to the end of the reaction.
The experimental conditions were studied to optimise glycerate production with selected catalysts, with particular regard to the effect of the NaOH/glycerol ratio, glycerol concentration, temperature, and glycerol/catalyst ratio. The best result was 92% selectivity to glycerate at full
conversion, obtained by oxidising glycerol at 30 ◦C, with a NaOH/glycerol ratio of 4, a glycerol/Au = 500, and 0.3 M concentration
Gold nanostructured materials for the selective liquid phase catalytic oxidation
No full textAu(0) sols were obtained in aqueous solutions by reduction of NaAuCl4 with NaBH4 in the presence of protective agents [the long chain compound poly(oxyethylene(23)lauryl ether (C12E23), the polymer poly{bis(2-chloroethyl)ether-alt-1,3-bis[3-(dimethylamino)propyl]urea} (PEG), the poly quaternary salt obtained by reaction of a polyethyleneglycole with the bisphenol A diglycidyl ether (PEU), and a polysaccharide (dextrin)]. The sols, characterized by TEM microscopy and UV-Vis spectroscopy, consisted of nanoparticles of different size (2.6-6.9 nm) depending on the used stabilizing agent. The colloidal solutions were immobilized on activated carbon. The carbon-supported gold catalysts were used in a model reaction for the selective liquid phase oxidation of ethylene glycol to glycolate (pO(2) = 300 kPa, T = 343 K, r.t. = 1 h, [EG] = 0.5 M, EG/Au = 1000, EG/NaOH = 1, EG = ethylene glycol). A comparison of the catalytic activity underlines the importance of the stabilizing agent in both the steps of sol formation and support impregnation
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