Hydroxyapatite is a biocompatible material with various applications. To meet the demand for industrial use of this material, a rapid and upscalable process for the synthesis of hydroxyapatite nanoparticles was developed using an in-house developed two-stage continuous flow hydrothermal reactor. In the framework of this study, phase pure and highly crystalline 30 to 115 nm long hydroxyapatite nanorods were produced for potential use as nanofertilizers. The phase composition of the nanorods was confirmed by X-ray diffraction. Particle size and shape were investigated using transmission electron microscopy. Inductively coupled plasma mass spectrometry was used to determine the Ca:P ratio. It was shown that the use of a second mixing stage allows the particle length to be decreased down to 30 nm without compromising on crystallinity. In addition to using different mixing stages, adjusting the pH and controlling the flow speed allow wide range size tuning of the produced particles. The experimental setup allows for continuous synthesis of phase pure and highly crystalline hydroxyapatite nanorods, ensuring the reproducibility and scalability of the process. Dispersive behavior and dissolution in citrate buffer at a hydroponic pH of 5.5 were studied to evaluate further possibilities of applying produced NPs on the plants.

中文翻译：

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作为潜在纳米肥料的尺寸可调羟基磷灰石纳米颗粒的可扩展合成

羟基磷灰石是一种具有多种应用的生物相容性材料。为了满足这种材料的工业应用需求，使用内部开发的两级连续流水热反应器开发了一种快速且可升级的羟基磷灰石纳米颗粒合成工艺。在本研究的框架中，生产了相纯且高度结晶的 30 至 115 nm 长的羟基磷灰石纳米棒，可用作纳米肥料。通过X射线衍射证实了纳米棒的相组成。使用透射电子显微镜研究颗粒尺寸和形状。使用电感耦合等离子体质谱法测定Ca:P比率。结果表明，使用第二个混合阶段可以将颗粒长度减小至 30 nm，而不会影响结晶度。除了使用不同的混合阶段外，调节 pH 值和控制流速还可以对所产生的颗粒进行大范围的尺寸调整。该实验装置允许连续合成相纯且高度结晶的羟基磷灰石纳米棒，确保该过程的再现性和可扩展性。研究了水培 pH 值为 5.5 时在柠檬酸盐缓冲液中的分散行为和溶解情况，以评估将生产的纳米颗粒应用于植物的进一步可能性。