The translation of nanoparticles to useful applications is often hindered by the reliability of synthetic methodologies to reproducibly generate larger particles of uniform size (diameter > 20 nm). The inability to precisely control nanoparticle crystallinity, size, and shape has significant implications on observed properties and therefore applications. A series of iron oxide particles have been synthesised and the impact of size as they agglomerate in aqueous media undergoing flow through a capillary tube has been studied. Reaction conditions for the production of large (side length > 40 nm) cubic magnetite (Fe₃O₄) have been optimised to produce particles with different diameters up to 150 nm. We have focussed on reproducibility in synthesis rather than dispersity of the size distribution. A simple oxidative cleavage of the as-synthesised particles surfactant coating transforms the hydrophobic oleic acid coated Fe₃O₄ to a hydrophilic system based on azelaic acid. The hydrophilic coating can be further functionalised, in this case we have used a simple biocompatible polyethylene glycol (PEG) coating. The ability of particles to either chain, flow, and fully/or partially aggregate in aqueous media has been tested in a simple in-house system made from commercial components. Fe₃O₄ nanoparticles (60–85 nm) with a simple PEG coating were found to freely flow at a 2 mm distance from a magnet over 3 min at a rate of 1 mL min⁻¹. Larger particles with side lengths of ~150 nm, or those without a PEG coating were not able to fully block the tube. Simple calculations have been performed to support these observations of magnetic agglomeration.

将纳米颗粒转化为有用的应用往往受到合成方法的可靠性的阻碍，这些方法可重复地产生尺寸均匀的较大颗粒（直径 > 20 nm）。无法精确控制纳米颗粒的结晶度、尺寸和形状对观察到的特性和应用具有重大影响。已经合成了一系列氧化铁颗粒，并研究了当它们在流过毛细管的水介质中聚集时尺寸的影响。生产大（边长 > 40 nm）立方磁铁矿（Fe ₃ O ₄) 已被优化以生产不同直径的颗粒，最大可达 150 nm。我们专注于合成的再现性而不是尺寸分布的分散性。合成的颗粒表面活性剂涂层的简单氧化裂解将疏水油酸涂覆的 Fe ₃ O ₄转化为基于壬二酸的亲水系统。亲水涂层可以进一步功能化，在这种情况下，我们使用了简单的生物相容性聚乙二醇 (PEG) 涂层。粒子在水性介质中链接、流动和完全/或部分聚集的能力已在由商业组件制成的简单内部系统中进行了测试。Fe ₃ O ₄发现具有简单 PEG 涂层的纳米颗粒（60-85 nm）可以在 3 分钟内以 1 mL min ^-1的速率在距磁体 2 mm 距离处自由流动。边长约为 150 nm 的较大颗粒或那些没有 PEG 涂层的颗粒无法完全阻塞管子。已经进行了简单的计算来支持这些磁团聚的观察结果。