Wan Ying, Liu Gang, Zhu Xinhua, Su Yan
School of Mechanical Engineering, Nanjing University of Science and Technology, Nanjing, Jiangsu 210094, Peoples Republic China.
Chem Cent J. 2013 Jan 24;7(1):14. doi: 10.1186/1752-153X-7-14.
Reversible assembly and disassembly of nanostructures has important function in controllable construction of nanodevices. There are several methods to achieve reversible assembly/disassembly, such as pH, temperature, DNA hybridization and so on. Among these methods, pH driven reversible assembly presents superiority due to its ease-of-use and no waste produced. Herein we report a novel design that use two single-stranded (ss) DNAs wrapped single walled carbon nanotubes (SWCNTs) for the pH controlled assembly of SWCNTs without generation of waste.
Both of the two DNAs with a same wrapping sequence of d(GT)20 and different free terminals showed a very high tendency to wrap around carbon nanotubes. The assembly was driven by the hybridization between the two free terminals of wrapped DNAs on the neighboring SWCNTs: i-motif (four-stranded C-quadruplex) and its complemental stranded G-quadruplex which would form tight tetraplexes and break the hybridization under slightly acidic conditions. Thus the assembly and disassembly are reversibly controlled by pH. And this assembly/disassembly process can be easily distinguished by naked eyes. Gel electrophoresis and Atomic Force Microscope are used to demonstrate the assembly and disassembly of SWCNTs at different pH.
A novel pH induced reversible assembly and disassembly of SWCNTs was realized which may have potential applications in the area of controlled assembly of nanostructures.
纳米结构的可逆组装和解组装在纳米器件的可控构建中具有重要作用。实现可逆组装/解组装有多种方法，如pH值、温度、DNA杂交等。在这些方法中，pH驱动的可逆组装因其易用性和无废物产生而具有优势。在此，我们报道了一种新颖的设计，即使用两条包裹在单壁碳纳米管（SWCNT）上的单链（ss）DNA来实现SWCNT的pH控制组装且不产生废物。
两条具有相同d(GT)20包裹序列和不同游离末端的DNA都表现出非常高的缠绕碳纳米管的倾向。组装是由相邻SWCNT上包裹的DNA的两个游离末端之间的杂交驱动的：i-基序（四链C-四链体）及其互补链G-四链体，它们在微酸性条件下会形成紧密的四链体并破坏杂交。因此，组装和解组装由pH值可逆控制。并且这种组装/解组装过程可以通过肉眼轻松区分。凝胶电泳和原子力显微镜用于证明不同pH值下SWCNT的组装和解组装。
实现了一种新颖的pH诱导的SWCNT可逆组装和解组装，这可能在纳米结构的可控组装领域具有潜在应用。
