Magnetic nanoparticles of Ga‐substituted ε‐Fe₂O₃ for biomedical applications: Magnetic properties, transverse relaxivity, and effects of silica‐coated particles on cytoskeletal networks

Abstract

Magnetic nanoparticles of ε-Fe 1.76 Ga 0.24 O 3 with the volume-weighted mean size of 17 nm were prepared by thermal treatment of a mesoporous silica template impregnated with metal nitrates and were coated with silica shell of four different thicknesses in the range 6-24 nm. The bare particles exhibited higher magnetization than the undoped compound, 22.4 Am 2 kg −1 at 300 K, and were characterized by blocked state with the coercivity of 1.2 T at 300 K, being thus the very opposite of superparamagnetic iron oxides. The relaxometric study of the silica-coated samples at 0.47 T revealed promising properties for MRI, specifically, transverse relaxivity of 89-168 s −1 mmol(f.u.) −1 L depending on the shell thickness was observed. We investigated the effects of the silica-coated nanoparticles on human A549 and MCF-7 cells. Cell viability, proliferation, cell cycle distribution, and the arrangement of actin cytoskeleton were assessed, as well as formation and maturation of focal adhesions.Our study revealed that high concentrations of silica-coated particles with larger shell thicknesses of 16-24 nm interfere with the actin cytoskeletal networks, inducing thus morphological changes. Consequently, the focal adhesion areas were significantly decreased, resulting in impaired cell adhesion. K E Y W O R D S cytoskeleton, cytotoxicity, epsilon polymorph, Ga-doped iron(III) oxide, transverse relaxivity How to cite this article: Královec K, Havelek R, Koutová D, et al. Magnetic nanoparticles of Ga-substituted ε-Fe 2 O 3 for biomedical applications: Magnetic properties, transverse relaxivity, and effects of silica-coated particles on cytoskeletal networks.

Insights into the Molecular Mechanisms Regulating Cell Behavior in Response to Magnetic Materials and Magnetic Stimulation in Stem Cell (Neurogenic) Differentiation

“…Furthermore, changes occurring in the cytoskeleton architecture and dynamics also play a significant role during the differentiation process, especially when they are associated with significant modifications to the cellular morphology [20][21][22]. Regarding the influence of magnetic cues on cellular behavior, there are numerous studies focusing on the reorganization of the cytoskeleton network and the effects on the focal adhesion complex or gap junctions [23][24][25]. It has been shown that a magnetic field and high concentrations of MNPs can lead to a decrease in proliferation and negatively affect FA and cytoskeleton components [26,27].…”

Dissecting the Inorganic Nanoparticle-Driven Interferences on Adhesome Dynamics

“…Soon after, Lo HM et al demonstrated that similar AuNP could disrupt platelet-derived growth factor (PDGF)-induced FAK phosphorylation, decreasing the vascular smooth muscle cell adhesion to a collagen I-rich ECM and inhibiting cell migration [144]. Recently, Královec K., et al observed that a novel type of complex nanoparticles, SiO 2 @Ga-substituted ε-Fe 2 O 3 , also induced FA shortening and a loss of stress fibers in human lung adenocarcinoma A549 [145]. Therefore, inorganic nanoparticles disturb fiber formation and stability at first glance, leading to an impaired cell migration.…”

Magnetism and magnetic phase transition in nanowires of diamagnetically diluted superstrong magnets ε-InxFe1-xO3

“…Metastable ε-Fe2O3 has attracted attention in recent years because of its enormous coercive force value up to 20 kE at room temperature and its ability to absorb electromagnetic waves in the millimeter range [3][4]. All together this provides great potential for the applicability of ε-Fe2O3 for photocatalysis, gas sensors, magnetic/electrical tunable high-speed wireless communication devices and biomedical applications [5][6][7][8][9][10]. ε-Fe2O3 is not well suited for permanent magnet applications due to its low residual magnetization.…”