Theory of structure-based carbon nanotube separations by ion-exchange chromatography of DNA/CNT hybrids
Theory of structure-based carbon nanotube separations by ion-exchange chromatography of DNA/CNT hybrids
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DOI：
10.1021/jp0452913
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发表时间：
2005-02-24
影响因子：
3.3
通讯作者：
Zheng, M
中科院分区：
文献类型：
--
作者：
Lustig, SR;Jagota, A;Zheng, M
单链DNA螺旋缠绕在单个单壁碳纳米管周围以形成DNA/CNT杂化物，其在水溶液中既稳定又可分散。通过离子交换色谱，混合物在离子强度下洗脱，该离子强度取决于核心纳米管的电子特性和直径，从而提供了通过手性分离纳米管的机制。我们提出了一个理论模型，这个分离过程中，解释了所有的显着特征实验观察到的日期，并提供准确的预测临界洗脱盐浓度。在固定相上的吸附和在移动的相中的对流冷凝之间的竞争的特征在于通过估计混合物的两个状态之间的自由能的差异。DNA缠绕几何形状，单壁碳纳米管的介电性能，混合长度和直径的参数研究表明，洗脱是最敏感的混合的有效电荷密度，主要由DNA螺旋间距。该模型正确地预测与金属纳米管的混合物比与半导体纳米管的混合物更弱的结合，并且较大直径的纳米管在稍后的时间被洗脱。
Single-stranded DNA wrap helically around individual single-walled carbon nanotubes to form DNA/CNT hybrids, which are both stable and dispersible in aqueous solution. Subjected to ion-exchange chromatography, a hybrid elutes at an ionic strength that depends on the electronic character and diameter of the core nanotube, thus providing a mechanism for separating nanotubes by chirality. We present a theoretical model for this separation process that explains all the salient features observed experimentally to date, and provides accurate predictions for critical elution salt concentration. The competition between adsorption on the stationary phase and counterion condensation in the mobile phase is characterized by estimating the difference in free energy between the two states of the hybrid. Parametric study of the DNA wrapping geometry, SWNT dielectric properties, hybrid length, and diameter indicate that the elution is most sensitive to the hybrid's effective charge density, primarily governed by the DNA helical pitch. The model correctly predicts hybrids with metallic nanotubes are weaker binding than hybrids with semiconducting nanotubes and larger diameter nanotubes are eluted at later times.