Qi Xiaohan, Li Minglin, Kuang Yun, Wang Cheng, Cai Zhao, Zhang Jin, You Shusen, Yin Meizhen, Wan Pengbo, Luo Liang, Sun Xiaoming
State Key Laboratory of Chemical Resource Engineering, P.O. Box 98, Beijing University of Chemical Technology, Beijing 100029 (P. R. China).
Chemistry. 2015 May 4;21(19):7211-6. doi: 10.1002/chem.201406507. Epub 2015 Mar 25.
Self-assembly of gold nanoparticles into one-dimensional (1D) nanostructures with finite primary units was achieved by introducing a thin salt (NaCl) solution layer into density gradient before centrifugation. The electrostatic interactions between Au nanoparticles would be affected and cause 1D assembly upon passing through the salt layer. A negatively charged polymer such as poly(acrylic acid) was used as an encapsulation/stabilization layer to help the formation of 1D Au assemblies, which were subsequently sorted according to unit numbers at succeeding separation zones. A centrifugal field was introduced as the external field to overcome the random Brownian motion of NPs and benefit the assembly effect. Such a facile "one-tube synthesis" approach couples assembly and separation in one centrifuge tube by centrifuging once. The method can be tuned by changing the concentration of interference salt layer, encapsulation layer, and centrifugation rate. Furthermore, positively charged fluorescent polymers such as perylenediimide-poly(N,N-diethylaminoethyl methacrylate) could encapsulate the assemblies to give tunable fluorescence properties.
通过在离心前向密度梯度中引入薄盐（NaCl）溶液层，实现了金纳米颗粒自组装成具有有限初级单元的一维（1D）纳米结构。金纳米颗粒之间的静电相互作用会受到影响，并在通过盐层时导致一维组装。使用带负电荷的聚合物（如聚丙烯酸）作为封装/稳定层，以帮助形成一维金组装体，随后在后续分离区根据单元数量进行分选。引入离心场作为外部场，以克服纳米颗粒的随机布朗运动，并有利于组装效果。这种简便的“单管合成”方法通过一次离心在一个离心管中实现组装和分离。该方法可以通过改变干扰盐层、封装层的浓度和离心速率进行调整。此外，带正电荷的荧光聚合物（如苝二酰亚胺-聚（N，N-二乙氨基乙基甲基丙烯酸酯））可以封装组装体，以赋予可调谐的荧光特性。
