National University of Science and Technology "MISIS", Moscow, 119049, Russia and Department of Medical Nanobiotechnology, Russian National Research Medical University, Moscow, 117997, Russia.
National University of Science and Technology "MISIS", Moscow, 119049, Russia.
J Mater Chem B. 2020 May 6;8(17):3886-3895. doi: 10.1039/c9tb02721a.
The chemical synthesis of nanoparticles with a preassigned size and shape is important for an optimized performance in any application. Therefore, systematic monitoring of the synthesis is required for the control and detailed understanding of the nucleation and growth of the nanoparticles. Here, we study Fe3O4-Au hybrid nanoparticles in detail using probes of the reaction mixture during synthesis and their thorough characterization. The proposed approach eliminates the problem of repeatability and reproducibility of the chemical synthesis and was carried out using laboratory equipment (standard transmission electron microscopy, X-ray diffraction, and magnetometry) for typically 10 μL samples instead of, for example, a dedicated synthesis and inspection at a synchrotron radiation facility. From the three independent experimental techniques we extract the nanoparticle size at 12 stages of the synthesis. These diameters show identical trends and good quantitative agreement. Two consecutive processes occur during the synthesis of Fe3O4-Au nanoparticles, the nucleation and the growth of spherical Fe3O4 nanoparticles on the surface of Au seeds during the heating stage and their faceting towards octahedral shape during reflux. The final nanoparticles with sizes of 15 nm Fe3O4 and 4 nm Au exhibit superparamagnetic behavior at ambient temperature. These are high-quality, close to stoichiometric Fe3O4 nanocrystals with nearly volumetric magnetic behavior as confirmed by the presence of the Verwey transition. Understanding the processes occurring during the synthesis allows the nanoparticle size and shape to be adjusted, improving their capabilities in biomedical applications.
具有预定尺寸和形状的纳米粒子的化学合成对于任何应用中的优化性能都很重要。因此，需要对合成过程进行系统的监测，以控制和详细了解纳米粒子的成核和生长。在这里，我们使用合成过程中反应混合物的探针，对 Fe3O4-Au 杂化纳米粒子进行了详细研究，并对其进行了彻底的表征。所提出的方法消除了化学合成重复性和再现性的问题，并且使用实验室设备（标准透射电子显微镜、X 射线衍射和磁强计）对通常为 10 μL 的样品进行了研究，而不是在例如同步辐射设施中进行专门的合成和检查。从三个独立的实验技术中，我们在合成的 12 个阶段提取了纳米粒子的尺寸。这些直径显示出相同的趋势和良好的定量一致性。在 Fe3O4-Au 纳米粒子的合成过程中，发生了两个连续的过程，在加热阶段，在 Au 种子表面上形成了球形 Fe3O4 纳米粒子的成核和生长，在回流过程中，它们向八面体形状的面心化。最终的纳米粒子的尺寸为 15nm Fe3O4 和 4nm Au，在室温下表现出超顺磁性。这些是高质量、接近化学计量比的 Fe3O4 纳米晶体，具有近乎体积磁行为，这一点从存在 Verwey 转变得到了证实。了解合成过程中发生的过程，可以调整纳米粒子的尺寸和形状，从而提高其在生物医学应用中的性能。
