Functionalized superparamagnetic nanoparticles (Nps) are among the most investigated research topics. In this study, we present an efficient protocol for gold deposition onto the surface of cobalt ferrite (CoFe 2 O 4 ) Nps by a simple one-pot reduction of AuCl 4 − ions with amino acid methionine, which, in turn, produces the biocompatible stabilizing shell. In contrast to previously reported gold deposition recipes, the one suggested herein is distinguished by the simplicity and prevention of monogold crystallite nucleation and growth in the deposition solution bulk. To demonstrate the preferential deposition of gold onto the surface of ferrite Nps, high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectroscopy (EDX), inductively coupled plasma mass spectrometry, and Fourriertransformed infrared spectroscopy (FTIR) investigations have been performed. The innovative gold deposition method is expected to open new horizons for the design of biocompatible water dispersible gold/methionine-functionalized ferrite nanoparticles by a simply controllable way.

We report the design and methodology for functionalization of the surface of small Co-ferrite nanoparticles with a mean size of up to 5.0 nm through the attachment of vitamin C molecules initiating [AuCl4] -reduction and the subsequent deposition of gold. By this method, Co-ferrite-Au nanoparticles have been fabricated for the first time in a simple and controllable manner, consisting of the determination of the consumed ascorbic acid content. The sequential addition of vitamin C and HAuCl4 to the ferrofluid at low concentrations leads to the formation of a gold shell on the ferrite core. This approach avoids the additional stabilization of ferrite nanoparticles before gold deposition, and is of great importance in view of the preparation of biodegradable superparamagnetic particles for nanomedicine applications. The deposition of gold onto the ferrite surface was proved herein by UV-vis absorption and energydispersive X-ray (EDX) spectroscopy, inductively coupled plasma mass spectrometry analysis, atomic force microscopy (AFM), high resolution transmission electron microscopy (HRTEM) and Mössbauer spectroscopy.

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Biocompatible superparamagnetic iron oxide nanoparticles (NPs) through smart chemical functionalization of their surface with fluorescent species, therapeutic proteins, antibiotics, and aptamers offer remarkable potential for diagnosis and therapy of disease sites at their initial stage of growth. Such NPs can be obtained by the creation of proper linkers between magnetic NP and fluorescent or drug probes. One of these linkers is gold, because it is chemically stable, nontoxic and capable to link various biomolecules. In this study, we present a way for a simple and reliable decoration the surface of magnetic NPs with gold quantum dots (QDs) containing more than 13.5% of Au+. Emphasis is put on the synthesis of magnetic NPs by co-precipitation using the amino acid methionine as NP growth-stabilizing agent capable to later reduce and attach gold species. The surface of these NPs can be further conjugated with targeting and chemotherapy agents, such as cancer stem cell-related antibodies and the anticancer drug doxorubicin, for early detection and improved treatment. In order to verify our findings, high-resolution transmission electron microscopy (HRTEM), atomic force microscopy (AFM), FTIR spectroscopy, inductively coupled plasma mass spectroscopy (ICP-MS), and X-ray photoelectron spectroscopy (XPS) of as-formed CoFe2O4 NPs before and after decoration with gold QDs were applied.

We report the study of gold clusters' attachment to magnetic nanoparticles by microwave processing for red-luminescent magnetic species formation.