Solubilization of Single Wall Carbon Nanotubes with Salmon Sperm DNA S. N. Kim * , K. M. Singh * , F. Ouchen †‡ , J. G. Grote † and R. R. Naik * * Air Force Research Laboratory, RXBP, WPAFB, OH, USA, Rajesh.Naik@wpafb.af.mil † Air Force Research Laboratory, RXPS, WPAFB, OH, USA, James.Grote@wpafb.af.mil ‡ University of Dayton, 300 College Park, Dayton, OH 45469 ABSTRACT Single wall carbon nanotubes (SWCNTs) have been highlighted among scientific communities due to their potential to advance numerous application areas, such as in nanoscale circuits, ultrathin, flexible, and transparent conductors, supercapacitors, field emitters, actuators, nanosized electrochemical probes, transistors, photovoltaic devices, and nanoscale sensors. Aside from their immense technological importance, enhancing the structural purity and homogeneity by obtaining well dispersed and fractionated samples could also enable us to better characterize and model the SWCNTs. Recently, it has been possible to separate and/or enrich fractions of SWCNTs according to metallicity and diameter (d t ). Deoxyribonucleic acids (DNAs), specifically in synthetic oligomeric form, have been playing an important role in the exfoliation and subsequent d t and metallicity dependent separation of SWCNTs. However, their extreme high price for the synthesis needs to be overcome for the cost-effective and bulk scale solubilization and separation of SWCNTs. In this paper, we present a solubilization study of commercially available SWCNTs by using the DNA extracted from waste materials of the salmon fishing industry through an enzyme isolation process. The optical properties, including NIR and circular dichroism spectra, are also presented. Keywords: single wall carbon nanotubes, DNA, dispersion, solubilization, spectroscopy 1 INTRODUCTION Single wall carbon nanotubes can be pictorially presented as the cylindrical roll-up of a simple flat graphene sheet containing carbon atoms in a hexagonal lattice, with a circumferential rolling vector of C h =na 1 +ma 2 , where n and m are integer and a 1 and a 2 are unit vectors. 1 Typically, their diameter varies from 0.4 to 3 nm and length ranges from tens of nanometers to micrometers by controlling the growth conditions and/or applying appropriate post-growth chemical treatments, such as oxidative shortening. 2, 3 The large scale growth of structurally perfect single wall carbon nanotubes has been typically performed via arc discharge, laser ablation, chemical vapor deposition (CVD), and plasma enhanced chemical vapor deposition (PECVD) methods. Among the growth processes, CVD and PECVD methods have appeared to be particularly important processes for the production of SWCNTs that contain minimal concentrations of graphitic nanoparticle contaminations. However, the extreme SWCNTs inter-tube aggregation forces, along with inhomogeneity in the chirality, pose significant obstacle in the achievement for technological breakthroughs where nanotubes of precisely defined length, diameter, and chirality are used. By wrapping 4, 5 and/or groove-binding 6 with SWCNTs via hydrophobic interactions, DNA has been recognized as one of the most efficient dispersion media that enables us to acquire both individually exfoliated samples and chirality- fractionated carbon nanotubes according to their diameter and metallicity. 5, 7 From a series of experiments, single stranded d(GT) n DNA has been recognized to exhibit not only individual-level nanotube dispersion, but also effective SWCNT chirality separation when eluted from an anion exchange column at various salt concentrations. 5, 7 However, the typical synthetic oligomer price for a d(GT) 20 , which is used mostly in the SWCNT dispersion and separation experiments, is ~25,000$/g. Usual oligo-DNA assisted SWCNT dispersion experiments are carried out with a DNA:SWCNT weight ratio of 1:1 and the majority of non-interacting DNAs are discarded. This poses a high price of $25 for oligo-DNA in treating every mg of carbon nanotubes, and thus, a cost-effective nucleic acid system is highly in demand. Here we present a solubilization and separation study of SWCNTs by using salmon sperm DNA (SaDNA), which is a byproduct of the fishing industry and costs 20$/g from the preparation method used in this work, as a dispersion media in water or D 2 O. We show that the SaDNA exfoliates and disperses SWCNTs on an individual level. The analysis on NIR and resonance Raman spectra from the solubilized nanotube samples will be presented along with the chirality dependent separation results from SaDNA mediated SWCNT dispersion. 2 EXPERIMENTS 2.1 DNA preparation Synthetic d(GT) 20 DNA was purchased from IDT and used to compare the solubility of SWCNTs to SaDNA 132 NSTI-Nanotech 2008, www.nsti.org, ISBN 978-1-4200-8503-7 Vol. 1