Surface Charge and Coating of CoFe₂O₄ Nanoparticles: Evidence of Preserved Magnetic and Electronic Properties

Abstract

Magnetic nanoparticles (MNPs) have shown exceptional potential for several biological and clinical applications. However, MNPs must be coated by a biocompatible shell for such applications. The aim of this study is to understand if and how the surface charge and coating can affect the electronic and magnetic properties of CoFe2O4 MNPs. The role of the surface on the total magnetic moment of MNPs is a controversial issue, and several effects can contribute to make it deviate from the bulk value, including the charge, the nature of the coating, and also the synthetic technique. Positively and negatively charged uncoated CoFe2O4 NPs as well as citrate-coated NPs were prepared by soft chemistry synthesis. The electronic properties and cationic distribution of CoFe2O4 NPs were probed by X-ray absorption spectroscopy (XAS), X-ray magnetic circular dichroism (XMCD), and X-ray photoemission spectroscopy (XPS) techniques and confirmed by theoretical simulations. The overall magnetic behavior and the hyperthermic properties were evaluated by magnetometry and calorimetric measurements, respectively. The results show that all of the investigated CoFe2O4 NPs have high magnetic anisotropy energy, and the surface charge and coating do not influence appreciably their electronic and magnetic properties. In addition, the citrate shell improves the stability of the NPs in aqueous environment, making CoFe2O4 NPs suitable for biomedical applications

Investigation of ZnFe2O4 spinel ferrite nanocrystalline screen‐printed thick films for application in humidity sensing

“…Satellite peaks are also noted at ~719.8 and ~733 eV. The positions of the two peaks and their satellites at BE higher for ~8 eV indicate the Fe 3+ oxidation state in the analyzed powder …”

Magnetic and antimicrobial properties of cobalt‐zinc ferrite nanoparticles synthesized by citrate‐gel method

“…This type of agglomeration affinity may be in general happened owing to the magnetic interactions among the CZF nanoparticles. 39 Hence, the SEM pictures may not provide the significant and true particle size of CZF materials. The EDS spectra manifested the CZF materials are of pure in nature thereby noting the presence of elements like Co, Zn, Fe, and Oxygen (Figure 4) including their atomic and weight percentages ( Figure 5A.…”

Thermoreversible magnetic nanochains

“…In general, magnetic nanoparticles (NPs) are attractive [22][23][24][25][26][27] for the above-mentioned applications due to the remarkable magnetic properties they maintain at scales of a few nanometers. Clever functionalization of the NP surface improves their stability; 28 magnetic properties; 29 or helps them to mediate their mutual supramolecular interactions, [30][31][32][33][34][35] or to react in the sense of dynamic covalent chemistry.…”