Pardo Alberto, Pujales Rosa, Blanco Mateo, Villar-Alvarez Eva M, Barbosa Silvia, Taboada Pablo, Mosquera Víctor
Grupo de Física de Coloides y Polímeros, Departamento de Física de la Materia Condensada, 15782-Santiago de Compostela, Spain.
Dalton Trans. 2016 Jan 14;45(2):797-810. doi: 10.1039/c5dt03923a.
In this work, we analyzed the effects of subtle changes in the synthetic conditions and synthetic parameters on the resulting size, shape, monodispersity, crystallinity and magnetic properties of iron oxide nanocrystals (IONCs) obtained through a modified one pot method for the production of mainly cubic-shaped nanoparticles (NPs). Cubic, octahedral and cuboctahedral shapes with different sizes and monodispersity could be obtained by slightly changing the stabilizer/precursor molar ratio, the precursor concentration, the reaction time and temperature and/or the heating rate. Their physical properties were evaluated using high-resolution transmission electron microscopy (HRTEM), X-ray powder diffraction (XRD), selected-area electron diffraction (SAED) and a superconducting quantum interference (SQUID) device. It was found that monodisperse cubic nanocrystals from ca. 25 to 94 nm could be obtained either by changing the precursor concentration, the heating rate or the reaction time. These cubic nanocrystals were ferrimagnetic in the whole temperature rage analyzed, with saturation magnetization values even larger than those of bulk magnetite. In addition, slightly truncated octahedral NPs could be achieved at relatively large heating ramp rates, whereas cubooctahedral NPs were derived by simply increasing the stabilizer/precursor molar ratio. The saturation magnetization of both types of NPs was slightly lower than the cubic ones, but they were still ferrimagnetic in the whole temperature range analyzed. Moreover, transfer to aqueous solution was possible by a ligand exchange with dimercaptosuccinic acid (DMSA) providing, at the same time, chemical groups for additional functionalization if required. The DMSA-coated cubic IONCs were fairly stable in culture medium, allowing their internalization by different cell types. The NPs inside the cells were located in the cytoplasm and most of them showed a perinuclear distribution. Moreover, a great cytocompatibility in a large range of particle concentrations was observed without the induction of morphological changes in the cultured cells.
在本工作中，我们分析了合成条件和合成参数的细微变化对通过改进的一锅法制备的主要为立方体形纳米颗粒（NPs）的氧化铁纳米晶体（IONCs）的尺寸、形状、单分散性、结晶度和磁性的影响。通过略微改变稳定剂/前驱体摩尔比、前驱体浓度、反应时间和温度以及/或者加热速率，可以获得具有不同尺寸和单分散性的立方体形、八面体形和立方八面体形。使用高分辨率透射电子显微镜（HRTEM）、X射线粉末衍射（XRD）、选区电子衍射（SAED）和超导量子干涉（SQUID）装置对它们的物理性质进行了评估。结果发现，通过改变前驱体浓度、加热速率或反应时间，可以获得约25至94 nm的单分散立方纳米晶体。这些立方纳米晶体在整个分析温度范围内呈亚铁磁性，其饱和磁化强度值甚至大于块状磁铁矿。此外，在相对较大的加热升温速率下可以获得略微截顶的八面体NPs，而通过简单增加稳定剂/前驱体摩尔比可以得到立方八面体NPs。这两种类型的NPs的饱和磁化强度略低于立方体形NPs，但在整个分析温度范围内仍呈亚铁磁性。此外，通过与二巯基琥珀酸（DMSA）进行配体交换可以将其转移到水溶液中，同时，如果需要的话，还提供了用于额外功能化的化学基团。DMSA包覆的立方体形IONCs在培养基中相当稳定，允许不同细胞类型将其内化。细胞内的NPs位于细胞质中，大多数呈核周分布。此外，在很大的颗粒浓度范围内观察到了良好的细胞相容性，且未诱导培养细胞发生形态变化。
