Cubic Anisotropic Co- and Zn-Substituted Ferrite Nanoparticles as Multimodal Magnetic Agents

Abstract

The use of magnetic nanoparticles as theranostic agents for the detection and treatment of cancer diseases has been extensively analyzed in the last few years. In this work, cubic-shaped cobalt and zinc-doped iron oxide nanoparticles with edge lengths in the range from 28 to 94 nm are proposed as negative contrast agents for magnetic resonance imaging and to generate localized heat by magnetic hyperthermia, obtaining high values of transverse relaxation coefficients and specific adsorption rates. The applied magnetic fields presented suitable characteristics for the potential validation of the results into the clinical practice in all cases. Pure iron oxide and cobalt- and zinc-substituted ferrites have been structurally and magnetically characterized, observing magnetite as the predominant phase and weak ferrimagnetic behavior at room temperature, with saturation values even larger than those of bulk magnetite. The coercive force increased due to the incorporation of cobalt ions, while zinc substitution promotes a significant increase in saturation magnetization. After their transfer to aqueous solution, those particles showing the best properties were chosen for evaluation in in vitro cell models, exhibiting high critical cytotoxic concentrations and high internalization degrees in several cell lines. The magnetic behavior of the nanocubes after their successful cell internalization was analyzed, detecting negligible variations on their magnetic hysteresis loops and a significant decrease in the specific adsorption rate values.

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

“…Similarly, a heating efficiency of about 3.5 kW/g was measured for 22 nm Co-Mn doped ferrites in aqueous dispersion; however, such heating performance was due to Brownian motion, not hysteresis, and consequently decreased in high viscosity glycerol solutions that simulate cellular media [37]. These results are in agreement with those reported in cubic Co-and Zn-substituted ferrites after their cell internalization [38], where the SAR showed a reduction of about 60% in the case of Zn 0.21 Fe 2.79 O 4 . The same tendency applies to monodisperse Fe 3 O 4 /Co x Zn 1-x Fe 2 O 4 core-shell NPs [39].…”

The Effect of Zn-Substitution on the Morphological, Magnetic, Cytotoxic, and In Vitro Hyperthermia Properties of Polyhedral Ferrite Magnetic Nanoparticles

“…In this context, the substitution of Fe 2+ (d 6 ) cations in B sites with Mn 2+ (d 5 ) cations, bearing a larger magnetic moment of 5µ B per formula unit due to their five unpaired valence electrons, led to an increase of the saturation magnetization (M s ) of ferrite particles and thus to an enhancement of their heating capabilities [17][18][19][20][21]. The replacement of Fe 2+ (d 6 ) cations in B sites by more anisotropic Co 2+ (d 7 ) cations, conducted to ferrite particles with larger coercivity values and a wider hysteresis loop, which improved considerably the production of heat under AMF [22][23][24][25]. A particular different situation is offered by the diamagnetic Zn 2+ (d 10 ) cations once incorporated in the spinel structure, as they can produce significant enhancement of the ferrite particle s magnetic moment, compared to pure Fe 3 O 4 [26][27][28].…”

“…Several synthesis routes have been employed for the preparation of ZnF particles, exhibiting different particle size histograms, cation distribution between the two sublattices, and magnetic properties. The preparation of single-crystalline monodisperse ZnF-particles with magnetic properties closed to bulk-like ones has been achieved by thermal decomposition of metal acetylacetonates and oleates in organic solvents at high temperatures [25,26,28,29,[31][32][33][34]. In most cases, this method enables the formation of secondary phases as wüstite [35].…”

Di- and tri-component spinel ferrite nanocubes: synthesis and their comparative characterization for theranostic applications

“…The 12 ± 1 nm Zn-ferrite NC (Zn 0.2 Fe 2.8 O 4 ) sample showed a significantly low coercive field and high saturation magnetization at both 300 K and 10 K, being superparamagnetic at 300 K, in accordance with the literature. 7,47 The inclusion of cobalt ions into the Zn-Co-ferrite NC of the 11 nm sample (Zn 0.1 Co 0.5 Fe 2.4 O 4 ) also showed superparamagnetic behaviour at 300 K, but the H c drastically increased at 10 K (1600 kA m −1 ), so other magnetic structures may have affected the overall magnetic features. In general, such a behaviour is ascribed to the formation of core-shell structures, 16,48 which may lead to the hypothesis that the NCs present an iron-rich core and a Zn/Co-rich shell ferrite structure.…”