Abstract A multistep procedure, employing akaganeite FeO(OH,Cl) as a precursor, was developed for the preparation of rod-like maghemite particles for medical applications. At first, akaganeite rods with length of several hundred nm and width of ≈85 nm were prepared under hydrothermal conditions and were subsequently coated with mesoporous silica. Such coating enabled to maintain the shape of rods during the following steps that involved structural transformation of akaganeite to maghemite, i. e. γ-Fe2O3. Then the original protective coating was removed by alkaline leaching, bare maghemite rods were isolated, and their structure and ferrimagnetic order were characterized by X-ray diffraction, TEM inspection, Mossbauer spectroscopy and SQUID magnetometry. The magnetization of the bare maghemite rods, that were formed by elongated clusters of ≈10–20 nm crystallites, made 47.0 and 41.7 Am2/kg in magnetic field of 3 T at 5 K and 300 K, respectively. The hysteresis loops of both the bare and coated products at 300 K and ZFC/FC studies showed that the maghemite particles were largely blocked at room temperature in spite of the small size of crystallites. Finally, the particles were equipped with standard silica coating for biological studies. An evaluation of cytotoxicity of this silica-coated product was performed on two cell lines, namely A549 and MCF-7. The viability of cells incubated with particles at the concentration of 0.10, 0.21 and 0.42 mmol(Fe)/L was determined after 24 h and 48 h of incubation, and the values normalized to the viability of negative control were generally higher than 95%. Moreover, the real-time monitoring of cell adhesion, proliferation, and cytotoxicity by an xCELLigence system during 72 h of the incubation with particles revealed only some decrease of the cell index for the MCF-7 cells at the high concentration.

中文翻译：

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二氧化硅包覆磁赤铁矿的棒状颗粒：通过赤镁石合成、表征和生物学特性

摘要 开发了一种采用赤镁矿 FeO(OH,Cl) 作为前驱体的多步程序，用于制备用于医疗应用的棒状磁赤铁矿颗粒。首先，在水热条件下制备了长度为数百纳米、宽度约为 85 纳米的赤金石棒，然后用介孔二氧化硅包覆。这种涂层能够在以下步骤中保持棒的形状，这些步骤涉及赤金矿到磁赤铁矿的结构转变，即 γ-Fe2O3。然后通过碱浸去除原有的保护涂层，分离出裸露的磁赤铁矿棒，并通过X射线衍射、TEM检查、穆斯堡尔光谱和SQUID磁力测定法对其结构和亚铁磁序进行表征。裸磁赤铁矿棒的磁化，由约 10–20 nm 微晶的细长簇形成，在 5 K 和 300 K 的 3 T 磁场中分别制成 47.0 和 41.7 Am2/kg。裸露和涂层产品在 300 K 和 ZFC/FC 研究中的滞后回线表明，尽管微晶尺寸很小，但磁赤铁矿颗粒在室温下大部分被阻塞。最后，这些颗粒配备了用于生物学研究的标准二氧化硅涂层。在两种细胞系，即 A549 和 MCF-7 上进行了这种二氧化硅涂层产品的细胞毒性评估。用浓度为 0.10、0.21 和 0.42 mmol(Fe)/L 的颗粒孵育的细胞的活力在孵育 24 小时和 48 小时后测定，归一化为阴性对照的活力值通常高于 95%。而且，