Abstract
During the past few decades, hybrid nanoparticles (HNPs) based on a magnetic material and gold have attracted interest for applications in catalysis, diagnostics and nanomedicine. In this paper, magnetic CoFe2O4/Au HNPs with an average particle size of 20 nm, decorated with 2 nm gold clusters, were prepared using methionine as a reducer and an anchor between CoFe2O4 and gold. The methionine was used to grow the Au clusters to a solid gold shell (up to 10 gold deposition cycles). The obtained nanoparticles (NPs) were studied by X-Ray diffraction (XRD), transmission electron microscopy (TEM), Fourier-transform infrared (FT-IR) spectroscopy, X-Ray photoelectron spectroscopy (XPS) and UV-vis spectroscopy techniques. The TEM images of the obtained HNPs showed that the surface of cobalt ferrite was covered with gold nanoclusters, the size of which slightly increased with an increase in the number of gold deposition cycles (from 2.12 ± 0.15 nm after 1 cycle to 2.46 ± 0.13 nm after 10 cycles). The density of the Au clusters on the cobalt ferrite surface insignificantly decreased during repeated stages of gold deposition: 21.4 ± 2.7 Au NPs/CoFe2O4 NP after 1 cycle, 19.0 ± 1.2 after 6 cycles and 18.0 ± 1.4 after 10 cycles. The magnetic measurements showed that the obtained HNPs possessed typical ferrimagnetic behavior, which corresponds to that of CoFe2O4 nanoparticles. The toxicity evaluation of the synthesized HNPs on Chlorella vulgaris indicated that they can be applied to biomedical applications such as magnetic hyperthermia, photothermal therapy, drug delivery, bioimaging and biosensing.
Highlights
The design, synthesis and applications of hybrid nanoparticles (HNPs) are hot research topics in the field of nanotechnology
Cobalt ferrite nanoparticles were synthesized using anion-exchange resin precipitation based on the ion exchange between the anions of the aqueous solution and a solid substance
We found that gold-containing nanoparticles with a non-continuous gold shell showed lower toxicity compared with bare CoFe2O4 nanoparticles
Summary
The design, synthesis and applications of hybrid nanoparticles (HNPs) are hot research topics in the field of nanotechnology. Among various iron oxide-based nanomaterials, magnetite has been the most popular for biomedical applications. It has the strongest magnetism among iron oxides. Magnetite is extremely sensitive to oxidation, decreasing its magnetic properties; it requires a protective capping layer [16,17]. Cobalt and nickel ferrites are often considered as alternatives to magnetite [18,19]. These materials are attractive due to their high chemical stability and significant magnetism
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