Citrate Stabilized Au‐FexOy Nanocomposites for Variable Exchange Bias, Catalytic Properties and Reversible Interaction with Doxorubicin

Abstract

Exchange bias effect in Au‐FexOy nanocomposites, prepared with regulated Au:Fe content, has been controlled using the variable iron content and the composition of FexOy. A green synthetic route has been adapted at room temperature in aqueous medium for such Au−Fe oxide nanocomposites. Diversity in FexOy compositions has been achieved through Au(III) reduction by Fe powder to obtain Au‐FexOy nanocomposites in presence of gold nanoparticles as seed and threshold amount of sodium citrate as stabilizing agent. The exchange bias effect in selective Au‐FexOy nanocomposites (5Fe, 6Fe, 7Fe and 9Fe) arises from the ferromagnetic‐antiferromagnetic (FM‐AFM) interaction between Fe3O4 and α‐Fe2O3 present in the samples. A theoretical model is used to explain the variation of the exchange bias, coercivity and magnetization for the different samples at various temperatures. These Au‐FexOy nanocomposites have been compared in terms of their catalytic activities for nitroarene reductions and reversible surface interaction with cancer drug doxorubicin.

Hybrid Nanoparticles Based on Cobalt Ferrite and Gold: Preparation and Characterization

“…As discussed above, in this paper, 10-15 nm magnetic nanoparticles of cobalt ferrite, decorated with 2 nm gold nanoclusters, were obtained. It is worth noting that the nanomaterials decorated with gold are of interest for catalytic applications [4,5,[20][21][22][23][24][25][26]70,71]. The gold-decorated nanoparticles were synthesized by Félix et al [22], using polyethyleneiminetreated Fe 3 O 4 as magnetic cores and sodium borohydride as a reducing agent; they were also synthesized by Silvestri et al [5], using CoFe 2 O 4 and 2,3-meso-dimercapto succinic acid as a bifunctional organic ligand.…”

“…Such a hybrid catalyst material has higher efficiency and lower cost due to the larger Au surface area, compared with gold NPs. It is also worth noting that it is possible to separate the catalyst using an external magnetic field [4,5,[20][21][22][23][24][25][26]. The catalytic properties of gold-coated magnetic nanoparticles can be varied by the type of coating (thick shell or decoration with nanoclusters) and the morphology and size of gold nanoparticles on the surface.…”

Seed free synthesis of polyethylene glycol stabilized gold nanoprisms exploiting manganese metal at low pH

“…The pH independent Mn/Mn 2+ couple along with PEG is responsible for the reduction of Au 3+ to Au 0 in the absence of HCl ( eqn (1) ). In order to inspect pH dependent behavior of redox reaction between Mn and Au( iii ), 24 this has been added to the solution. Addition of 10 equivalents of HCl (Au : HCl = 1 : 10) to the reaction mixture shows the generation of effervescence as expected due to liberation of hydrogen gas after reaction with Mn metal ( Scheme 1 ).…”

“…The growth mechanism of anisotropic nanoparticles has been inuenced by reduction potential, which is indirectly governed by variations in seed concentration, pH, halide concentration, reducing agent, and surface passivating stabilizing agents. 23 In our previous reports with Fe and Zn, seedmediated syntheses produced gold-iron oxide 24 or gold-zinc oxide nanocomposites. 25 In this study, we aimed to synthesize nanoparticles without the incorporation of the reducing metal in the nal nano-structure.…”

Hybrid Nanoparticles Based on Cobalt Ferrite and Gold: Preparation and Characterization

“…Gold is one of the most effective coating materials to protect magnetic nanoparticles and increase their biocompatibility. Additionally, the optical and catalytic properties of gold-coated magnetic nanoparticles can be varied by the type of coating (thick shell or decoration with nanoclusters) and the morphology and size of gold nanoparticles on the surface [20][21][22].…”