Magnetic nanoparticles of ε‐Fe_1.76Ga_0.24O₃ 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 Am² 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.

中文翻译：

---

用于生物医学应用的 Ga 取代的 ε-Fe2 O3 磁性纳米粒子：磁性、横向弛豫率和二氧化硅涂层粒子对细胞骨架网络的影响。

ε-Fe _1.76 Ga _0.24 O ₃磁性纳米粒子的体积加权平均尺寸为 17 nm，是通过对浸渍有金属硝酸盐的介孔二氧化硅模板进行热处理制备的，并涂有四种不同厚度的二氧化硅壳，范围为 6– 24 纳米。裸颗粒表现出比未掺杂的化合物更高的磁化强度，在 300 K 时为22.4 Am ² kg ^-1，并且具有在 300 K 时具有 1.2 T 矫顽力的阻塞状态的特征，因此与超顺磁性氧化铁非常相反。二氧化硅涂层样品在 0.47 T 下的弛豫研究揭示了 MRI 的有希望的特性，特别是横向弛豫率为 89-168 s ^-1 mmol(fu) ^-1观察到取决于壳厚度的 L。我们研究了二氧化硅包覆的纳米粒子对人 A549 和 MCF-7 细胞的影响。评估细胞活力、增殖、细胞周期分布和肌动蛋白细胞骨架的排列，以及粘着斑的形成和成熟。我们的研究表明，具有 16-24 nm 更大壳厚度的高浓度二氧化硅包覆颗粒会干扰肌动蛋白细胞骨架网络，从而诱导形态变化。因此，粘着斑区域显着减少，导致细胞粘附受损。