Highly magnetic core-shell nanoparticles with a unique magnetization mechanism.
Highly magnetic core-shell nanoparticles with a unique magnetization mechanism.
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DOI：
10.1002/anie.201100101
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发表时间：
2011-05-09
影响因子：
16.6
通讯作者：
Weissleder, Ralph
中科院分区：
文献类型：
--
作者：
Yoon, Tae-Jong;Lee, Hakho;Shao, Huilin;Weissleder, Ralph
具有高磁矩和非常小尺寸的磁性纳米颗粒（MNP）正在积极开发中，因为此类材料在生物技术和医学中的应用越来越多。[1]铁磁金属，而不是其相应的氧化物，已被建议作为MNP的理想成分，其上级磁化。[2]不幸的是，Monopoly MNP通常需要保护层来防止逐渐氧化。然而，迄今为止，大多数核/壳方法都产生了次优的磁化，因为壳是通过人工氧化核[3，4]或通过用非磁性材料涂覆而形成的。[5]在这里，我们提出了一种制备用于生物医学用途的高磁性Monoclonal MNP的方法。颗粒由元素铁（Fe）核和人工铁氧体壳（Fe@MFe2O4，M= Fe，Mn，Co）组成。Fe芯被扩大成热稳定的铁磁状态以增加整体磁化。随后，在磁芯上生长保护性铁氧体壳，并进行金属掺杂以进一步增强磁化。所得到的颗粒显示出独特的磁性特征，即具有可忽略不计的磁滞现象。进一步的分析揭示了一种新的磁化过程，其中壳通过在小磁场下引导磁化过程来有效地降低铁磁芯的磁化率。所得MNP获得高饱和磁化强度，但具有可忽略的剩磁，以防止粒子间聚集。通过对皮摩尔范围内的蛋白质和单个癌细胞的高灵敏度检测证明了颗粒的实用性。该机制和MNP可以作为一种新的策略，在制备稳定的，高磁性的，但分散的纳米粒子从铁磁晶体。
Magnetic nanoparticles (MNPs) with high magnetic moments and very small size are under active development, since such materials have growing uses in biotechnology and medicine.[1] Ferromagnetic metals, rather than their corresponding oxides, have been suggested as an ideal constituent for MNPs for their superior magnetization.[2] Unfortunately, monometallic MNPs typically require protective layers to prevent progressive oxidation. To date, however, most core/shell approaches have yielded suboptimal magnetization, as the shell was formed either by artificially oxidizing the core [3, 4] or by coating it with non-magnetic materials.[5]Here we present an approach to preparing highly magnetic, monometallic MNPs for biomedical use. The particles consisted of an elemental iron (Fe) core and an artificial ferrite-shell (Fe@ MFe2O4, M= Fe, Mn, Co). The Fe cores were enlarged into a thermally stable ferromagnetic state to increase the overall magnetization. Subsequently, protective ferrite shells were grown onto the cores and metal-doped to further enhance magnetization. The resultant particles displayed a unique magnetic feature, the presence of hysteresis with negligible coercivity. Further analysis revealed a novel magnetization process wherein the shell effectively reduces the coercivity of the ferromagnetic cores by leading the magnetization process at small magnetic fields. The resulting MNPs attain high saturation magnetization but with negligible remanence to prevent inter-particle aggregations. The utility of the particles was demonstrated through the highly sensitive detection of proteins in the pico-molar ranges and of single cancer cells. The mechanism and MNP featured here could serve as a new strategy in preparing stable, highly magnetic and yet dispersible nanoparticles from ferromagnetic crystals.
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影响因子：
16.6
作者：
Lee, Hakho;Yoon, Tae-Jong;Weissleder, Ralph
通讯作者：
Weissleder, Ralph
影响因子：
5.4
作者：
Cheng, Jing;Ni, Xiaomin;Zhang, Dongen
通讯作者：
Zhang, Dongen
影响因子：
15
作者：
Peng, Sheng;Wang, Chao;Sun, Shouheng
通讯作者：
Sun, Shouheng
影响因子：
41.2
作者：
Park, J;An, KJ;Hyeon, T
通讯作者：
Hyeon, T
影响因子：
3.3
作者：
Farrell, D;Majetich, SA;Wilcoxon, JP
通讯作者：
Wilcoxon, JP