Preparation and Characterization of 3 nm Magnetic NiAu Nanoparticles

Abstract

Using PAMAM dendrimers as nanoparticle templates, a synthetic route to prepare 3 nm magnetic NiAu nanoparticles was developed. Aqueous solutions of hydroxyl-terminated generation 5 PAMAM dendrimers in 25 mM NaClO 4 were shown to bind aqueous Ni II . Coreduction of Ni II and Au III salts yielded bimetallic dendrimer stabilized nanoparticles, which were extracted into toluene with decanethiol. Characterization of the resulting monolayer protected clusters (MPCs) with transmission electron microscopy and UV-visible, atomic absorption, and X-ray photoelectron spectroscopies suggested that the MPCs had substantial surface enrichment in Au. Superconducting quantum interference device (SQUID) measurements at 5 K show the bimetallic MPCs to have low coercivity and saturation magnetization relative to bulk Ni. Solution nuclear magnetic resonance (NMR) studies using the Evans method showed the bimetallic nanoparticles retain magnetic properties at ambient temperatures.

Enhanced Oxygen Activation over Supported Bimetallic Au−Ni Catalysts

“…The details of these synthetic protocols and characterization information have already been reported for monometallic Au NPs and Ni@Au core-shell NPs. 30,39 Catalyst Synthesis and Characterization. The total metal: dendrimer ratio was held constant at 147:1 for all syntheses; only the Au:Ni ratios were adjusted to yield catalysts with Au: Ni molar ratios ranging from pure Au to 75% Ni (mass ratios from 6 to 1).…”

“…Several groups, including our own, have recently reported solution syntheses to Ni-Au NPs. 26,30,31 Notably, one study showed that Ni-Au NPs are appropriate precursors to heterogeneous Au/NiO/SiO 2 catalysts. 26 On the basis of these results, and particularly our previous experience preparing Ni-Au NPs in solution, we therefore set out to tune Au catalysts by incorporating varying amounts of Ni into the NP syntheses.…”

Synthesis, Characterization, and Applications of Dendrimer-Encapsulated Zero-Valent Ni Nanoparticles as Antimicrobial Agents

“…As of date, nanosized inorganic particles with simple or complex structures are currently being used in electronics [1], optical devices [2,3], sensor devices [4,5], surface enhanced Raman scattering (SERS) [6,7], catalysis [8][9][10], biomedicine [11], wound healing [12], antimicrobial properties [13,14], gene expression [15], and magnetic resonance imaging [16]. However, due to the limitation of current synthesizing methodologies to produce nanoparticles with precise physical and chemical details, concerns have increased over nanoparticle usage in the healthcare industry.…”

Structure and composition of Au/Co magneto-plasmonic nanoparticles

“…In a 2008 study, Auten et al [23] have reported ∼"3-nm magnetic NiAu nanoparticles" using decane-thiolate monolayer protection, which "had essentially the same Au:Ni ratio as was set in the synthesis (Au:Ni = 2.1)." The evidence indicated the surfaces are enriched in gold.…”

“…[16] There exist several studies on the synthesis and properties of Au-Ni and Au-Co NPs. [17][18][19][20][21][22][23] However, thiolate protected Au/Co NPs have not been reported so far. In general terms, segregation of Au toward the surface is predicted, considering only the metal-metal interaction, i.e., neglecting the effect of the surfactant molecules.…”