Article pubs.acs.org/JPCC
High Specific Absorption Rate and Transverse Relaxivity Effects in Manganese Ferrite Nanoparticles Obtained by an Electrochemical Route Eva Mazarío,⊥ Jorge Sánchez-Marcos,⊥ Nieves Menéndez,⊥ Magdalena Cañete,φ Alvaro Mayoral,§,† Sara Rivera-Fernández,† Jesús M. de la Fuente,†,‡,◊ and Pilar Herrasti*,⊥ ⊥
Departamento de Química Física Aplicada, Facultad de Ciencias, Universidad Autónoma de Madrid, C/Francisco Tomás y Valiente, 7, 28049, Madrid, Spain φ Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, C/Darwin 2, 28049 Madrid, Spain § Laboratorio de Microscopias Avanzadas (LMA), Zaragoza, Spain † Instituto de Nanociencia de Aragón, Universidad de Zaragoza, Mariano Esquillor s/n, 50018 Zaragoza, Spain ‡ Instituto de Ciencia de Materiales de Aragón, CSIC/Universidad de Zaragoza, C/Pedro Cerbuna 12, 50009, Zaragoza, Spain ◊ Institute of Nano Biomedicine and Engineering, Key Laboratory for Thin Film and Microfabrication Technology of the Ministry of Education, Research Institute of Translation Medicine, Shanghai Jiao Tong University, Dongchuan Road 800, 200240 Shanghai, People’s Republic of China S Supporting Information *
ABSTRACT: Superparamagnetic iron oxide-based nanoparticles (SPIONS) have attracted an enormous amount of attention for their potential use in biomedical applications, due to their good biocompatibility and low toxicity. The current study considers citric acidconjugated manganese ferrite and its synergy to be used in MRI and in hyperthermia treatment, thus showing theragnostic applications. High colloidal stability was obtained with this functionalization. SPIONS with superparamagnetic behavior of crystal sizes of approximately 20 nm were obtained via an electrochemical synthesis method. One of the highest specific absorption rate (SAR) values was achieved in this work (1661 W g−1), under a magnetic field of 30 mT at 717 kHz frequency, compared with other magnetic ferrites in the literature. These nanoparticles dissipate heat through Néel relaxation and, together with the high SAR value obtained, indicate an excellent material for hyperthermia treatment of cancer. In addition, these nanoparticles exhibit transverse relaxivity behavior, with an r2 value of 394 mM−1 s−1, i.e., at least two times higher than the value of a commercial magnetic contrast agent based on iron oxides. Finally, no toxicity effects of these nanoparticles are evidenced; as a result, these nanoparticles are appropriate for in vivo application.
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INTRODUCTION
substitution of M(X) for Co, Ni, Mn, etc., with different properties. Although the hysteresis loop of ferromagnetic MNPs is advantageous, such materials are almost completely inappropriate for biomedical applications such as hyperthermia due to the possibility of aggregating in the vessel. For this reason, superparamagnetic nanoparticles are preferred for in vivo applications. The magnetization disappears once the external magnetic field is removed, which inhibits particle aggregation and the possible embolization of the capillary vessels. The requirements to be fulfilled for the use of magnetic nanoparticles in biomedical applications can be summarized in the following aspects. The magnetic moments should be sufficiently high for achieving higher signal sensitivity for better contrast in
Magnetic properties are crucial for the successful performances of magnetic nanoparticles (MNPs) in biomedical applications, such as magnetic resonance imaging (MRI), drug delivery, cellular signaling, and hyperthermia.1−3 It is important to devise nanoparticles with high and tunable magnetism, especially saturation magnetization (Ms) values, while maintaining a good degree of monodispersity. For decades, iron oxide (Fe3O4) nanoparticles have served as a model material in the biomedical research field. In fact, some commercially available iron oxide magnetic fluids have been developed by various enterprises such as Chemicell, Micromod, and Bayer-Schering.4 However, currently, all of the efforts are focused on developing new materials with enhanced magnetic properties. As a result, ferrites of the general formula (M(X)+2O)(M(Y)2+3O3) and with M(X) and M(Y) = Fe in the case of magnetite can generate multiple compounds with enhanced properties via © 2015 American Chemical Society
Received: October 31, 2014 Revised: February 24, 2015 Published: March 4, 2015 6828
DOI: 10.1021/jp510937r J. Phys. Chem. C 2015, 119, 6828−6834
Article
The Journal of Physical Chemistry C
were characterized via X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), thermogravimetric analysis, inductively coupled plasma optical emission spectrometry (ICP-OES), and a SQUID magnetometer. The stable colloidal solution obtained was evaluated for hyperthermia application by calculating the specific absorption rate (SAR) for different frequencies and magnetic fields. The use of the nanoparticles as contrast agents for magnetic resonance images was also evaluated by quantification of its r1 and r2 values. Finally, the viability of the nanoparticles was studied using HeLa cells to verify the absence of cytotoxicity.
magnetic resonance imaging (MRI) and for improving the heating efficiency in magnetic hyperthermia. Chemical stability should be ensured under physiological conditions; in this way, the use of an organic cover on the nanoparticles is able to prevent aggregation in physiological medium. The magnetic nanoparticles should present low or negligible toxicity. Furthermore, the degree of crystallinity and dispersibility in terms of size and shape of the nanoparticles are the critical parameters affecting the performance of the nanoparticles when used in therapeutic and diagnostic techniques. Finally, to prevent easy excretion by the reticuloendothelial system (RES), the overall size of the nanoparticles must be
