Abstract
In this work, we report the synthesis and characterization of three magnetic nanosystems, CoFe2O4, CoFe2O4@ZnFe2O4, and CoFe2O4@MnFe2O4, which were developed as potential theranostic agents for magnetic hyperthermia and magnetic resonance imaging (MRI). These nanosystems have been thoroughly characterized by X-ray Diffraction (XRD), Transmission Electron Miscroscopy (TEM), Dark Field-TEM (DF-TEM), Vibrating Sample Magnetometry (VSM), and inductive heating, in order to elucidate their structure, morphology, and magnetic properties. The bi-magnetic CoFe2O4@ZnFe2O4 and CoFe2O4@MnFe2O4 nanoparticles (NPs) exhibited a core-shell structure with a mean average particle size of 11.2 ± 1.4 nm and 14.4 ± 2.4 nm, respectively. The CoFe2O4@MnFe2O4 NPs showed the highest specific absorption rate (SAR) values (210–320 W/g) upon exposure to an external magnetic field, along with the highest saturation magnetization (Ms). Therefore, they were selected for functionalization with the PEGylated ligand to make them stable in aqueous media. After the functionalization process, the NPs showed high magnetic relaxivity values and very low cytotoxicity, demonstrating that CoFe2O4@MnFe2O4 is a good candidate for in vivo applications. Finally, in vivo MRI experiments showed that PEGylated CoFe2O4@MnFe2O4 NPs produce high T2 contrast and exhibit very good stealth properties, leading to the efficient evasion of the mononuclear phagocyte system. Thus, these bi-magnetic core-shell NPs show great potential as theranostic agents for in vivo applications, combining magnetic hyperthermia capabilities with high MRI contrast.
Highlights
Nowadays, cancer continues to be one of the most frequent and severe diseases, with a global estimate in 2018 of 18.1 million new cases and 9.6 million deaths [1]
The heating capability of bi-magnetic NPs can be evaluated through their specific absorption rate (SAR), which is related to surface and shape anisotropy, thee degree of spin disordering, and exchange anisotropy at the interface between the magnetic phases
The core-shell CoFe2O4@MnFe2O4 (CF@MF) NPs were synthesized by the seed-mediated growth method. 80 mg of CF particles suspended in hexane were added to a reaction system that was similar to that described above containing 1 mmol Mn(acac
Summary
Cancer continues to be one of the most frequent and severe diseases, with a global estimate in 2018 of 18.1 million new cases and 9.6 million deaths [1]. In the last few years, there has been a growing interest in the development of new CAs based on nanotechnology in order to overcome this limitation [8,9,10,11] In this sense, bi-magnetic core-shell nanoparticles (NPs) have emerged as a very promising option for the development of new MRI CAs with outstanding magnetic properties [12,13,14]. The bi-magnetic core-shell structure has been shown to increase their heating efficiency by an order of magnitude when compared to its single-core counterpart [23]. Bi-magnetic NPs that consist of both soft and hard magnetic phases can greatly enhance their SAR due to the interfacial exchange coupling between the magnetic core-shell layers [23,27]. The relaxivity, biodistribution, and pharmacokinetics studies demonstrated the high potential of these bi-magnetic NPs for theranostic applications
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