DNA-Controlled Partition of Carbon Nanotubes in Polymer Aqueous Two-Phase Systems

Abstract

Sorting single-wall carbon nanotubes (SWCNTs) of different chiralities is both scientifically interesting and technologically important. Recent studies have shown that polymer aqueous two-phase extraction is a very effective way to achieve nanotube sorting. However, works published to date have demonstrated only separation of surfactant-dispersed SWCNTs, and the mechanism of chirality-dependent SWCNT partition is not well understood. Here we report a systematic study of spontaneous partition of DNA-wrapped SWCNTs in several polymer aqueous two-phase systems. We show that partition of DNA-SWCNT hybrids in a given polymer two-phase system is strongly sequence-dependent and can be further modulated by salt and polymer additives. With the proper combination of DNA sequence, polymer two-phase system, and partition modulators, as many as 15 single-chirality nanotube species have been effectively purified from a synthetic mixture. As an attempt to provide a unified partition mechanism of SWCNTs dispersed by surfactants and by DNA, we present a qualitative analysis of solvation energy for SWCNT colloids in a polymer-modified aqueous phase. Our observation and analysis highlight the sensitive dependence of the hydration energy on the spatial distribution of hydrophilic functionalities.

Adsorption and Desorption of Single‐Stranded DNA from Single‐Walled Carbon Nanotubes

“…Prior to investigating ssDNA desorption from SWCNTs, ssDNA adsorption was investigated to both confirm adsorption and to determine baseline values for characterizing subsequent desorption. (GT) 20 was chosen as the model ssDNA oligomer because it has been used for the chirality‐specific separation of SWCNTs and because we have found that longer ssDNA strands yield a higher concentration of SWCNT in suspension after probe sonication and centrifugation (typical optical density x dilution factor 20–30, see Figure S1 in the Supporting Information) . The photographs of the suspension in Figure (a) shows the produced SWCNT suspension was stable (for months) and recorded a zeta potential of −42 mV, which is similar to other reports of CNT‐DNA suspensions and similar in magnitude to SWCNT suspensions with anionic surfactant sodium deoxycholate (Figure S2) .…”

High‐Efficiency Separation of (6,5) Carbon Nanotubes by Stepwise Elution Gel Chromatography

“… a) The (6,5) SWCNTs separated by ATP methods also have a high purity, but the detailed purity value was not evaluated by authors of Refs. .…”

Long-Term In Vivo Biocompatibility of Single-Walled Carbon Nanotubes

“…Purification of the (9,4) nanotube from the unsorted ssCTTC 3 TTC-SWCNT sample was performed using the aqueous two-phase extraction method 18–20 . In brief, ssCTTC 3 TTC-SWCNT was mixed with a solution containing a final concentration of 7.76% polyethylene glycol (PEG, molecular weight 6 kDa, Alfa Aesar), and 15.0% polyacrylamide (PAM, molecular weight 10 kDa, Sigma Aldrich).…”