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首页> 外文期刊>Nanotechnology >Colloidal stability of iron oxide nanocrystals coated with a PEG-based tetra-catechol surfactant
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Colloidal stability of iron oxide nanocrystals coated with a PEG-based tetra-catechol surfactant

机译：PEG基四邻苯二酚表面活性剂包覆的氧化铁纳米晶体的胶体稳定性

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摘要

Long-term colloidal stability of magnetic iron oxide nanoparticles (NPs) is an important goal that has not yet been fully achieved. To make an advance in our understanding of the colloidal stability of iron oxide NPs in aqueous media, we prepared NPs comprising a monodisperse (13 nm) iron oxide core coated with a PEG-based (PEG: polyethyleneglycol) surfactant. This consists of a methoxy-terminated PEG chain (MW = 5000 Da) bearing four catechol groups via a diethylenetriamine linker. The surfactant was grafted onto the nanocrystals by ligand exchange monitored by infrared spectroscopy. The colloidal stability of these nanoparticles was probed by monitoring the time evolution of the Z-average intensity-weighted radius Rh and volume-weighted size distribution P_v obtained from analysis of dynamic light scattering data. The nanoparticles showed no sign of aggregation for four months in deionized water at room temperature and also when subjected to thermal cycling between 25 and 75 °C. In 0.01 M PBS (phosphate buffered saline), aggregation (if any) is slow and partial; after 66 h, about 50% of NPs have not aggregated. Aggregation is more effective in 0.15 M NH_4AcO buffer, where isolated particles are not observed after 66 h, and especially in acidic NH_4AcO/AcOH buffer, where aggregation is complete within 1 h and precipitation is observed. The differing stability of the NPs in the above aqueous media is closely related to their ζ potential.
机译：磁性氧化铁纳米颗粒（NPs）的长期胶体稳定性是一个尚未完全实现的重要目标。为了使我们对水介质中的氧化铁NPs的胶体稳定性有更深入的了解，我们制备了包含单分散（13 nm）氧化铁核的NPs，这些核芯涂有基于PEG的（PEG：聚乙二醇）表面活性剂。它由通过二亚乙基三胺接头带有四个邻苯二酚基团的甲氧基封端的PEG链（MW = 5000 Da）组成。通过红外光谱监测的配体交换将表面活性剂接枝到纳米晶体上。通过监测从动态光散射数据分析获得的Z平均强度加权半径Rh和体积加权尺寸分布P_v的时间演变，可以探测这些纳米粒子的胶体稳定性。纳米粒子在去离子水中在室温下四个月内以及在25到75°C的热循环下都没有聚集迹象。在0.01 M PBS（磷酸盐缓冲液）中，聚集（如果有）缓慢且局部; 66小时后，约50％的NP尚未聚集。在0.15 M NH_4AcO缓冲液（66小时后未观察到分离的颗粒）中，聚集更有效，尤其是在酸性NH_4AcO / AcOH缓冲液中（在1 h内完成聚集并观察到沉淀）更有效。在上述水性介质中，NP的不同稳定性与其ζ电位密切相关。

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