Dispersion stability and exothermic properties of DNA-functionalized single-walled carbon nanotubes

Carbon nanotubes act as a photon antenna that serves as an effective "molecular heater" around the near-infrared (NIR) region. This exothermic generation can be used as a possible heating source for hyperthermia therapy. The current study reports the dispersible and exothermic properties with NIR irradiation for single-walled carbon nanotubes (SWNTs) treated with a strong acid (acid-treated SWNTs), and the SWNTs further functionalized with double-stranded DNA (DNA-functionalized SWNTs: DNA-SWNTs). DNA-SWNTs significantly improved the dispersibility of SWNTs when compared with the acid-treated SWNTs. The binding ratio of the acid-treated SWNT and DNA was calculated to be 3.1 (DNA/SWNTs) from the phosphorous content in the DNA-SWNT. This interaction of the SWNTs and DNA would contribute to the stable dispersion of the DNA-SWNTs in a culture medium. With NIR irradiation by a halogen lamp light source, the acid-treated SWNTs and the DNA-SWNTs showed strong heat evolution in vitro (in a culture medium) and in vivo (in the subcutaneous tissue of a mouse) condition without any invasive effect on the non-SWNT area. The results of this study suggested that the functionalization with DNA was an efficient approach to improve the dispersibility of SWNTs in body fluids, and the DNA-SWNT would be a promising source for photo-induced exothermic generation.