Synthesis of Silica-Coated Silver-Cobalt Ferrite Nanoparticles for Biomedical Applications

  • Shadab Dabagh
  • Ghasem DiniEmail author
Original Paper


In this work, a series of silver-substituted cobalt ferrite (AgxCo1-xFe2O4, 0 ≤ x ≤ 0.1) nanoparticles (NPs) were synthesized, and then a sample with monophase structure and optimum magnetic properties was coated with an amorphous silica layer. First, Ag-substituted Co-ferrite NPs were synthesized via a sol-gel auto combustion method from aqueous metal nitrates solutions. Then, all the powders were characterized by several techniques such as X-ray diffraction (XRD), field emission electron microscopy (FE-SEM), and vibrating sample magnetometry (VSM). These results showed that when the Ag content was between 0 and 0.08, the synthesized powders were the cubic spinel structure, having spherical-shaped particles with an average size of about 20–25 nm. Afterward, the silica coating was applied on the surfaces of the selected sample (i.e., Ag0.08Co0.92Fe2O4 NPs with monophase structure and optimum magnetic properties) by a sol-gel approach based on the Stöber process from the tetraethyl orthosilicate (TEOS) as the precursor of silica. Transmission electron microscopy (TEM), Fourier-transform infrared (FTIR) spectroscopy, and zeta potential investigations were used to study the characteristics of the silica-coated Ag-Co-ferrite NPs. The results of FTIR and TEM analyses confirmed the presence of the silica coating on the surfaces of the Ag-Co-ferrite NPs. Although the silica-coated sample showed the saturation magnetization (MS) value slightly lower than that of the uncoated one, however, its magnetic properties are suitable for use in different biomedical applications. Also, a water-based suspension containing the silica-coated Ag-Co-ferrite NPs showed a more negative zeta potential value at the pH of 7 in comparison with a suspension containing uncoated ones. Therefore, it can be concluded that the synthesized silica-coated Ag0.08Co0.92Fe2O4 NPs in this study could be considered as a good candidate for the preparation of biomedical ferrofluids.


Silver-cobalt ferrite nanoparticles Sol-gel method Magnetic properties Silica coating Suspension stability 



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© Springer Science+Business Media, LLC, part of Springer Nature 2019

Authors and Affiliations

  1. 1.Department of Nanotechnology Engineering, Faculty of Advanced Sciences and TechnologiesUniversity of IsfahanIsfahanIran

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