Bi-Magnetic Core-Shell CoFe2O4@MnFe2O4 Nanoparticles for In Vivo Theranostics

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.

Finding the Limits of Magnetic Hyperthermia on Core-Shell Nanoparticles Fabricated by Physical Vapor Methods

“…With regards to the improvement in SLP due to an interphase exchange mechanisms [26], an example shows synergistic effects (SLP~500 W/g) in soft MnFe 2 O 4 and hard CoFe 2 O 4 bimagnetic clusters when compared with the homomagnetic 9 nm counterparts (~100 and~200 W/g for Mn-and Co-ferrite, respectively) [27]. Such SLP values are similar to many others in the literature [28][29][30][31][32][33]. Overall, despite the superior magnetic hyperthermia response in many core-shell systems, recent experimental and theoretical studies failed to reproduce heating efficiencies above a few hundreds of watts per gram [34], in line with our observations (Table 2).…”

Application of Radiosensitizers in Cancer Radiotherapy

“… 206 Among them, ZnFe 2 O 4 , MnFe 2 O 4 , CoFe 2 O 4 nanoparticles were widely investigated. 207 For example, Meidanchi et al confirmed that ZnFe 2 O 4 nanoparticles interacted with γ-rays to produce photoelectric effect resulting in a higher release level of electron in radioresistant cells. 208 Studies also indicated that ZnFe 2 O 4 nanoparticles could be used as radiosensitizers.…”

Understanding MNPs Behaviour in Response to AMF in Biological Milieus and the Effects at the Cellular Level: Implications for a Rational Design That Drives Magnetic Hyperthermia Therapy toward Clinical Implementation

“…Even more impressive results were obtained with Zn 0.4 Fe 2.6 O4@CoFe 2 O 4 core-shell MNPs prepared with a cubic shape in which the SAR was above 10 kW/g [ 105 ]. Although these are outstanding SAR values compared to other MNPs [ 106 ], the synthesis of homogeneous core-shell structures with a controlled shell thickness remains a challenge.…”