Differentiating Left- and Right-Handed Carbon Nanotubes by DNA

Published

December 28, 2016

Author(s)

Ming Zheng, Geyou Ao, Jason K. Streit, Jeffrey A. Fagan

Abstract

The emergence of macromolecules of defined structures is a crucial step in the evolution of life. The mechanism by which these structures are selected from astronomical numbers of biopolymer sequences has long been a topic of controversy1,2. Experimenting structure selection from man-made macromolecular libraries may shed light to the mechanism of natural selection, and may also lead to the discovery of novel materials for technological applications. DNA-wrapped single-wall carbon nanotubes3-5 form a man-made library of enormous size due to the combinatorial diversity of nanotube structure and DNA sequence. Here, we report the use of polymer aqueous two-phase systems to select special DNA-wrapped carbon nanotubes, each of which has an ordered DNA structure bound to a nanotube of defined handedness, resembling a well-folded biomacromolecule with innate stereo-selectivity. By screening over 300 DNA sequences, we are able to achieve unprecedented nanotube enantiomer selection across the entire chiral angle range. The screening has also identified a rare DNA sequence that adopts two distinct folds on a pair of nanotube enantiomers, respectively, rendering them large differences in fluorescence intensity and chemical reactivity. This finding establishes a first example of functionally distinguishable right- and left-handed nanotubes. Mechanistic analysis, aided by structure-specific nanotube optical transitions6, suggests that sensitive dependence of hydration energy on structure variation makes conformational entropy minimization an implicit criterion in the aqueous two-phase selection, resulting in exquisite selectivity towards ordered structures. Our study introduces a new method to select well-folded bio- and bio/nano-molecules, and suggests a hydration energy driven mechanism that could be operative in the natural selection of biomacromolecules.

Citation

Journal of the American Chemical Society

Pub Type

Journals

Keywords

carbon nanotubes, DNA, selection, aqueous two-phase

Citation

Zheng, M. , Ao, G. , Streit, J. and Fagan, J. (2016), Differentiating Left- and Right-Handed Carbon Nanotubes by DNA, Journal of the American Chemical Society (Accessed July 17, 2024)