Effect of DNA on Fundamental Characteristics of Single-Walled Carbon Nanotubes; Length Distribution and Thermal Stability

Abstract

Single-stranded DNA has been demonstrated to enable single-particle exfoliation of single-walled carbon nanotubes (SWCNTs) in aqueous environments as well as suppress their known toxicological effects. The resultant fundamental properties of DNA-SWCNT hybrids are significant when these nanomaterials are applied to mechanical and biological systems. Accurate characterization of their length distributions is of great importance regarding their application as a clinical diagnostic agent. Here, we show that DNA-SWCNT hybrids differentially bind to freshly-cleaved mica in a manner that significantly depends upon the sequence of DNA. By displacing the DNA from the SWCNTs, we show that the length distributions of the resulting surfactant-coated SWCNTs are statistically identical and suggest that a DNA-wrapping can give inaccurate length distributions in image-derived approaches. Secondly, enhancing the thermal stability of SWCNTs is crucial when these materials are applied to high temperature applications. We examined the thermal decomposition temperature and rate of DNA functionalized carbon nanomaterials using thermogravimetric analysis and found that functionalization with DNA significantly increases the thermal decomposition temperature of all examined carbon nanomaterials in the order SWCNTs > C60 > RGO > MWCNTs. We attribute these increases in decomposition temperature to the fact that DNA, an intumescent molecular entity that increases in volume upon heating, shields the hybridized carbon nanomaterials from flame and elevated temperatures. Enhancing the thermal decomposition properties of carbon nanomaterials with non-toxic flame retardants enables the realization of environmentally friendly high temperature sensing and electronics applications.