Silica encapsulation of ferrimagnetic zinc ferrite nanocubes enabled by layer-by-layer polyelectrolyte deposition.
Silica encapsulation of ferrimagnetic zinc ferrite nanocubes enabled by layer-by-layer polyelectrolyte deposition.
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DOI：
10.1021/acs.langmuir.5b00268
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发表时间：
2015-03-24
期刊：
影响因子：
--
通讯作者：
Granger MC
中科院分区：
文献类型：
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作者：
Park J;Porter MD;Granger MC
磁性纳米颗粒（MNPs）稳定悬浮液具有大磁矩（m, per particle），在广泛的生物学应用中有着巨大的用途。然而，由于这些系统中经常存在强磁耦合相互作用，因此稳定单个、高矩、铁磁性和铁磁性纳米颗粒是具有挑战性的。本文描述了一种新的方法，在中间层的多电解质沉积步骤后，用二氧化硅封装大的，即>100 nm的铁磁锌铁氧体纳米立方（zfnc）。种子型zfnc形状和尺寸均匀，具有较高的饱和质量磁矩（σs ~100 emu/g， m~4×10−13 emu/粒）。对于本文所述的MNP系统，只有在沉积由聚烯丙胺和聚苯乙烯磺酸盐交替组成的聚电解质多层后，才能成功地实现二氧化硅封装和离散zfnc的创建。在没有中间聚电解质层的情况下，磁偶极子-偶极子相互作用导致嵌入在二氧化硅基体中的线性链状zfnc的形成。通过电子显微镜、能量色散x射线光谱、红外光谱、粉末x射线衍射、动态光散射（流体动力尺寸和ζ-势）和振动样品磁强计对颗粒样品进行了表征。这些表征的结果，这是在每个合成步骤后进行的，并提出了合成细节。
Stable suspensions of magnetic nanoparticles (MNPs) with large magnetic moment, m, per particle have tremendous utility in a wide range of biological applications. However, due to the strong magnetic coupling interactions often present in these systems, it is challenging to stabilize individual, high moment, ferro- and ferrimagnetic nanoparticles. A novel approach to encapsulate large, i.e., >100 nm, ferrimagnetic zinc ferrite nanocubes (ZFNCs) with silica after an intermediary layer-by-layer polyelectrolyte deposition step is described in this paper. The seed ZFNCs are uniform in shape and size and have high saturation mass magnetic moment (σs ~100 emu/g, m~4×10−13 emu/particle at 150 Oe). For the MNP system described within, successful silica encapsulation and creation of discrete ZFNCs were realized only after depositing polyelectrolyte multilayers composed of alternating polyallylamine and polystyrene sulfonate. Without the intermediary polyelectrolyte layers, magnetic dipole-dipole interactions led to the formation of linearly chained ZFNCs embedded in a silica matrix. Characterization of particle samples was performed by electron microscopy, energy-dispersive X-ray spectroscopy, infrared spectroscopy, powder X-ray diffraction, dynamic light scattering (hydrodynamic size and ζ-potential), and vibrating sample magnetometry. The results of these characterizations, which were performed after each of the synthetic steps, and synthetic details are presented.