Nanoparticles copper

Fig. 7. TEM image of starch capped copper nanoparticles 3.2 Bimetallic nanoparticles...

The mode of action of starch capped copper nanoparticles (SCuNPs) was compared with that of the well-known antibiotic amphicillin (Fig. 9). There was a drastic decrease in the optical density of compounds containing SCuNPs and ampicillin, ultimately reaching almost zero suggesting that there were no more bacteria present in the culture. AmpiciUin at a concentration of 100 pg/ml has the ability to lyse E.coli almost immediately [29]. The same effect was produced by SCuNPs at 365 ng/ml concentration. The cell lysis occurs at the expense of the fact that at the point of cell division there occurs a deformation of the cell envelope. The decrease in optical density is possibly associated with the cell-envelope deformation occurring at the point of cell division [30]. 

The biological impact of starch capped copper nanoparticles on mouse embryonic fibroblast (3T3L1) cells in vitro) was also evaluated by various parameters. More than 85 % of the 3T3Llcells were found to be viable, even after 20 hours time exposure which implies minimum impact on cell viability and morphology. The study demonstrates dose dependent cytotoxic potential of SCuNPs, that is non cytotoxic in the nanogram dose and moderately cytotoxic in the microgram doses (Fig. 10). Comparison of SCuNPs with Cu ions and uncapped copper nanoparticles (UCuNPs) revealed that, ions are more cytotoxic than SCuNPs. This observation supports the theory of slow release of ions from starch coated nanoparticles. 

Fig. 10. Effect of starch capped copper nanoparticles on cell viability (MTT assay) in case of mouse embryonic fibroblast (3T3L1).

We investigated the catalytic performance of the CU2O coated copper nanoparticles for Ullmann coupling reactions. When the coupling reactions using aryl bromides such as 2-... 

Similarly, Pd, Ag, and Pd-Ag nanoclusters on alumina have been prepared by the polyol method [230]. Dend-rimer encapsulated metal nanoclusters can be obtained by the thermal degradation of the organic dendrimers [368]. If salts of different metals are reduced one after the other in the presence of a support, core-shell type metallic particles are produced. In this case the presence of the support is vital for the success of the preparation. For example, the stepwise reduction of Cu and Pt salts in the presence of a conductive carbon support (Vulcan XC 72) generates copper nanoparticles (6-8 nm) that are coated with smaller particles of Pt (1-2 nm). This system has been found to be a powerful electrocatalyst which exhibits improved CO tolerance combined with high electrocatalytic efficiency. For details see Section 3.7 [53,369]. 

Table 2. Conditions for preparation of cubic copper nanoparticles via seed (S)-mediated method.

Ko WY, Chen WH, Tzeng SD et al (2006) Synthesis of pyramidal copper nanoparticles on gold substrate. Chem Mater 18 6097-6099... 

Haas I, Shanmugam S, Gedanken A (2006) Pulsed sonoelectrochemical synthesis of size-controlled copper nanoparticles stabilize by poly(N-vinylpyrrolidone). J Phys Chem B 110 16947-16952... 

However, in Ar and H2 atmospheres, the formation of H2O2 was arrested due to the scavenging of OH radicals by the hydrogen [75] producing only pure copper nanoparticles. Thus argon and hydrogen mixture produced even more H radicals and reduced Cu2+ ions to Cu+ as a consequence of sonication in the aqueous... 

Salkar RA, Jeevanandam P, Kataby G, Arana ST, Koltipin yuri, Palchik O, Gedanken A (2000) Elongated copper nanoparticles coated with a zwitterionic surfactant. J Phys Chem B 104 893-897... 

Kitchens, C.L. and Roberts, C.B. (2004) Copper nanoparticle synthesis in compressed liquid and supercritical fluid reverse micelle systems. Industrial and Engineering Chemistry Research, 43 (19), 6070-6081. 

An interesting sonochemical synthesis of elongated copper nanoparticles (approx. 50 X 500 nm) has been described [164]. The principle of the method is the use of an organised medium of aqueous cetyltrimethylammonium p-toluenesulphonate as the supporting fluid for sonication. The resulting nanoparticles are produced from the sonication of copper hydrazine carboxylate in the interconnected threadlike micelles which act as a template. The nanoparticles are coated with a layer of the surfactant. In the absence of the detergent the particles were spherical (ca. 50 nm). 

Gadhe, J.B., Gupta, R.B. 2007. Hydrogen production by methanol reforming in supercritical water catalysis by in situ-generated copper nanoparticles. Int J Hydrogen Energy 32 2374-2381. 

Similar to chemical vapor deposition, reactants or precursors for chemical vapor synthesis are volatile metal-organics, carbonyls, hydrides, chlorides, etc. delivered to the hot-wall reactor as a vapor. A typical laboratory reactor consists of a precursor delivery system, a reaction zone, a particle collector, and a pumping system. Modification of the precursor delivery system and the reaction zone allows synthesis of pure oxide, doped oxide, or multi-component nanoparticles. For example, copper nanoparticles can be prepared from copper acetylacetone complexes [70], while europium doped yttiria can be obtained from their organometallic precursors [71]. 

J.M.N. Zen, C.T. Hsu, A.S. Kumar, H.J. Lyuu and K.Y. Lin, Amino acid analysis using disposable copper nanoparticle-plated electrodes, Analyst, 129 (2004) 841-845. 

Schmittel, M., Kalsanl, V., Kienle, L., Simple and supramolecular copper complexes as precursors in the HRTEM induced formation of crystalline copper nanoparticles. Chem. Commun. 2004, 1534-1535. 

Male KB, Hrapovic S, Liu YL, Wang DS, Luong JHT. Electrochemical detection of carbohydrates using copper nanoparticles and carbon nanotubes. Analytica Chimica Acta 2004, 516, 35-41. 

Fig. 15.12. Specific catalytic activity vs. surface density of copper nanoparticles on thermally oxidized silicon in reactions involving chlorohydrocarbons (1) CC14 + C8H16 at 150°C, (2) the same at 130°C and e = 10, (3) isomerization of dichlorobutenes at 110°C, (4) isomerization of dichlorobutenes at 130°C, and (5) CC14 + C10H22 at 130°C.

Fig. 15.15. Specific catalytic activity vs. surface density of copper nanoparticles in dichlo-robutene isomerization at T = 110°C (1) oxidized silicon support and (2) silicon support.

Using formula (4), compare the value of the potential drop across the oxide sheath of copper nanoparticle with the thermal energy kT. In calculation, use the value of copper nuclei radius R — 1.7 nm, the thickness of Cu20 sheath d — 0.7 nm, and the dielectric constant of the sheath ed 4. 

Behrens M, Furche A, Kasatkin I, Trunschke A, Busser W, Muhler M, Kniep B, Fischer R, Schlogl R. The potential of microstructural optimization in metal/oxide catalysts Higher intrinsic activity of copper by partial embedding of copper nanoparticles. ChemCatChem. 2010 2(7) 816-818. 

Gunter et al. (2001) XAS, TGA Cu/ZnO Microstructure of activated copper nanoparticles, detection of strain + n.a Methanol synthesis/ steam reforming... 

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