Synthesis of Water Dispersible and Catalytically Active Gold-Decorated Cobalt Ferrite Nanoparticles

Abstract

Hetero-nanoparticles represent an important family of composite nanomaterials that in the past years are attracting ever-growing interest. Here, we report a new strategy for the synthesis of water dispersible cobalt ferrite nanoparticles (CoxFe3-xO4 NPs) decorated with ultrasmall (2-3 nm) gold nanoparticles (Au NPs). The synthetic procedure is based on the use of 2,3-meso-dimercaptosuccinic acid (DMSA), which plays a double role. First, it transfers cobalt ferrite NPs from the organic phase to aqueous media. Second, the DMSA reductive power promotes the in situ nucleation of gold NPs in proximity of the magnetic NP surface. Following this procedure, we achieved a water dispersible nanosystem (CoxFe3-xO4-DMSA-Au NPs) which combines the cobalt ferrite magnetic properties with the catalytic features of ultrasmall Au NPs. We showed that CoxFe3-xO4-DMSA-Au NPs act as an efficient nanocatalyst to reduce 4-nitrophenol to 4-aminophenol and that they can be magnetically recovered and recycled. It is noteworthy that such nanosystem is more catalytically active than Au NPs with equal size. Finally, a complete structural and chemical characterization of the hetero-NPs is provided.

Anisotropic Gold Nanoparticles in Biomedical Applications

“…The use of selected organic molecules exposed on the surface of NPs to reduce gold have been used even for the synthesis of other hybrid NPs [ 68 ], and has the great advantage to realize the reduction of gold in one-step, without the need to prepare seeds. The final step of this protocol is based on the dissolution of the polymeric template by using an organic solvent as DMF or THF, affording an exciting hollow/multibranched gold nanostructures.…”

Nanostructured Spinel Ferrites: Synthesis, Functionalization, Nanomagnetism and Environmental Applications

“…In an important report on the synthesis of Fe 3 O 4 and other ferrite NPs, Hyeon et al [59] used iron(III) oleate as an organometallic precursor with the purpose to avoid environmental harmful reagents like Fe(CO) 5 [60] and Fe[acac] 3 [61]. Also, there is no need for external reducing agents and extra surfactant stabilizers [36,[61][62][63]. The authors obtained high yields of wellcrystallized monodispersed NPs with D values ranging from 9-22 nm by varying the solvent boiling point.…”

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

“…HNPs are important due to their multi-functionalities that are difficult to achieve by a simple mixture of individual components. Due to the combination of physical and chemical (magnetic, optical) properties of compound substances, they can be used in various fields, such as chemistry, physics, microelectronics, biotechnology, catalysis and medicine [1][2][3][4][5].…”

“…Another approach is to form a surface complex with gold ions. The surface of the magnetic material is modified with bifunctional ligands, such as citrate [29,30], dithiosuccinic acid [5] and methionine [31]. The bifunctional ligand must have a high affinity for both the magnetic nanoparticle and gold ions.…”