Separation of nanoparticles in a density gradient: FeCo@C and gold nanocrystals.
Separation of nanoparticles in a density gradient: FeCo@C and gold nanocrystals.
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DOI：
10.1002/anie.200805047
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发表时间：
2009
影响因子：
16.6
通讯作者：
Dai, Hongjie
中科院分区：
文献类型：
--
作者：
Sun, Xiaoming;Tabakman, Scott M.;Seo, Won-Seok;Zhang, Li;Zhang, Guangyu;Sherlock, Sarah;Bai, Lu;Dai, Hongjie
纳米材料的尺寸和几何形状控制对于发现内在尺寸/形状依赖的性质和自下而上的方法用于制造功能纳米器件是重要的。[1-10]已经采用两种一般策略来产生尺寸均匀的纳米晶体。一种方法是在合成过程中通过调整生长参数直接控制粒度;[1-3，5，7-9]另一种是合成后分离。在后一种情况下，存在很大的能力来提高尺寸分离效率。差速离心可以从胶体系统中去除大而不稳定的颗粒，但缺乏对颗粒大小的精确控制。[9，11]在胶体系统中添加可调节量的“反溶剂”[19]（包括CO2）[12]可以使沉淀过程更可控。其他方法包括过滤[14]（包括渗滤[15]）、电泳[16，17]和色谱方法[11，18]，这些方法可以产生具有窄形状和尺寸分布的颗粒级分。为了保持或改善纳米颗粒（NP）分离的质量，同时解决液-固相分离过程中的粘附和堵塞问题，完全液相分离方法是非常有吸引力的。常用于生物大分子分离的等密度离心[20]依赖于密度梯度和超离心，根据细微的密度差异分离组分，并已应用于单壁碳纳米管（SWNT）的直径和电子依赖性分离。[13然而，等密度密度梯度离心方法在扩展到金属纳米颗粒的分离时达到了限制。这种方法要求用于分离的组分具有梯度范围内的密度。水性密度梯度介质通常具有小于1.4gcm-3的密度，这比金属纳米颗粒的密度小得多。这种重纳米晶体的尺寸或形状分离在它们的制备和用于各种应用中仍然是一个问题。
Size and geometric control of nanomaterials are important to the discovery of intrinsic size/shape dependent properties and bottom up approaches for the fabrication of functional nanodevices.[1–10] Two general strategies have been employed to create size-uniform nanocrystals. One method is direct particle size control during synthesis by adjusting growth parameters;[1–3, 5, 7–9] the other is post-synthesis separation.[11–19] Much capacity exists to improve size separation efficacy in the latter case. Differential centrifugation can remove large and unstable particles from colloidal systems, but lacks precise control over particle size.[9, 11] Addition of adjustable amounts of “anti-solvent”[19](including CO2)[12] into colloidal systems may make precipitation processes more controllable. Other methods include filtration [14](including diafiltration [15]), electrophoresis,[16, 17] and chromatographic methods [11, 18] that can produce particle fractions with narrow shape and size distributions.To maintain or improve the quality of nanoparticle (NP) separation, whilst addressing the issues of adhesion and clogging in liquid–solid phase separation processes, a completely liquid phase separation method is highly appealing. Isopycnic centrifugation, which is often used for biomacro-molecule separation,[20] relies upon a density gradient and ultracentrifugation to separate components according to subtle density differences, and has been applied for diameter and electronic-dependent separation of single-walled carbon nanotubes (SWNT).[13, 21] However, the isopycnic density-gradient centrifugation method reaches a limitation when it is extended to the separation of metal nanoparticles. Such a method requires that the components for separation have densities within a gradient range. Aqueous density gradient media usually have densities less than 1.4 gcm− 3, which is much less than the density of metal nanoparticles. Size or shape separation of such heavy nanocrystals remains an issue, both in their preparation and utility for various applications.
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影响因子：
10.8
作者：
Arnold, MS;Stupp, SI;Hersam, MC
通讯作者：
Hersam, MC
影响因子：
41.2
作者：
Seo, Won Seok;Lee, Jin Hyung;Dai, Hongjie
通讯作者：
Dai, Hongjie
影响因子：
15
作者：
Li, Xiaolin;Tu, Xiaomin;Dai, Hongjie
通讯作者：
Dai, Hongjie
影响因子：
9.9
作者：
Sun, Xiaoming;Liu, Zhuang;Dai, Hongjie
通讯作者：
Dai, Hongjie
影响因子：
4.9
作者：
Arnaud, I;Abid, JP;Girault, HH
通讯作者：
Girault, HH