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Direct Observation of the Wrapping/Unwrapping of ssDNA around/from SWCNT at Single-Molecule Level: Towards Tuning the Binding Mode and Strength

Abstract

Complexation of single-stranded DNA (ssDNA) with a chiral single-walled carbon nanotube (SWCNT) exhibits surprising efficacy in CNT dispersion and sorting, optical sensing, and nanoelectronic device design. Studying the wrapping/unwrapping mechanism is challenging because an in situ method at single-molecule level is required. Here, we developed a method based on single-molecule force spectroscopy to monitor the unwrapping/wrapping of ssDNA from/around SWCNT. Our results reveal that the wrapping/unwrapping processes are reversible in water, and these processes occur in an equilibrium manner driven mainly by π-π interactions between DNA bases and CNT. In phosphate buffered saline, the unwrapping process is loading rate-dependent, and ssDNA wrapping around CNT undergoes two distinct stages dominated by both π-π interaction and hydrogen bonding. In addition, our results show that salts could further stabilize ssDNA/CNT complexes by blocking the electrostatic interactions between adjacent DNA segments and by catalyzing the formation of hydrogen bonds between DNA bases. The stability of ssDNA/CNT are dependent on DNA sequence and CNT chirality. These results deepen our understanding of ssDNA-CNT interactions and provide effective means to tune the binding mode and strength.

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Supplementary files

Publication details

The article was received on 31 Jul 2018, accepted on 06 Sep 2018 and first published on 06 Sep 2018


Article type: Paper
DOI: 10.1039/C8NR06150E
Citation: Nanoscale, 2018, Accepted Manuscript
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    Direct Observation of the Wrapping/Unwrapping of ssDNA around/from SWCNT at Single-Molecule Level: Towards Tuning the Binding Mode and Strength

    Z. Li, Y. Song, A. Li, W. Xu and W. Zhang, Nanoscale, 2018, Accepted Manuscript , DOI: 10.1039/C8NR06150E

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