Poor stability and dispersibility, as well as aggregation are considered as major challenges in clinical application of iron oxide nanoparticles (IONPs). Several studies have shown that the synthesis parameters and post-synthesis treatments e.g., drying methods, have the capability to improve the particles' characteristics. Herein, we investigate the combined effect of synthesis and post-treatment parameters on the particle size, stability and magnetism of IONPs. Magnetite (FeO) NPs were prepared via co-precipitation and post-treated using different methods, i.e. (i) freeze dried at –53 °C, 0.133 mbar for 48 h (liquid nitrogen frozen (LFD) and freezer frozen (FFD)), (ii) vacuum oven dried (VOD) at 60 °C for 24 h, and (iii) kept wet colloidal (WET), dispersed in deionized water. The FeO NPs’ chemical functional groups, size, shape, crystallinity, stability, aggregation, porosity, and magnetic properties were further analysed using different characterisation techniques. Analytical results showed that, while the WET sample had the best stability and significantly less aggregation at different temperatures, amongst post-treated FeO NPs, LFD sample exhibited the best stability (up to 37 °C), dispersion and smallest polydispersity index. Furthermore, all dried NPs had superparamagnetic characteristics, while, LFD FeO NPs had better magnetic properties and stability than other drying methods.

中文翻译：

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反应及后处理条件对磁性氧化铁纳米粒子理化性质的影响

稳定性、分散性差以及聚集被认为是氧化铁纳米粒子（IONPs）临床应用的主要挑战。多项研究表明，合成参数和合成后处理（例如干燥方法）能够改善颗粒的特性。在此，我们研究了合成和后处理参数对 IONP 的粒径、稳定性和磁性的综合影响。通过共沉淀制备磁铁矿 (FeO) NP，并使用不同的方法进行后处理，即 (i) 在 –53 °C、0.133 mbar 下冷冻干燥 48 小时（液氮冷冻 (LFD) 和冷冻冷冻 (FFD)） ，(ii) 在 60°C 真空烘箱干燥 (VOD) 24 小时，和 (iii) 保持湿胶体 (WET)，分散在去离子水中。使用不同的表征技术进一步分析了 Fe3O 纳米颗粒的化学官能团、尺寸、形状、结晶度、稳定性、聚集、孔隙率和磁性。分析结果表明，虽然WET样品在不同温度下具有最好的稳定性和显着较少的聚集，但在后处理的Fe3O NPs中，LFD样品表现出最好的稳定性（高达37°C）、分散性和最小的多分散指数。此外，所有干燥的纳米颗粒都具有超顺磁特性，而LFD Fe3O 纳米颗粒比其他干燥方法具有更好的磁性能和稳定性。