Controlled Patterning of Carbon Nanotube Energy Levels by Covalent DNA Functionalization

Each structural form of single-wall carbon nanotube (SWCNT) has remarkable and well-defined electronic and optical properties, but it has not been possible to achieve spatial or energetic 10 modulation of those properties in controllable ways. We present here a simple method for using chemical reactions with single-stranded DNA (ssDNA) to accomplish such modulation. When aqueous suspensions of SWCNTs coated with ssDNA are exposed to singlet oxygen under ambient conditions, the nanotubes selectively form covalent bonds to the guanine nucleotides. This locally modulates semiconducting SWCNT energy levels and red-shifts their emission 15 wavelengths by up to 10%. Both the magnitude and spatial pattern of these shifts can be controlled by selecting the nucleotide sequence used to coat the nanotubes. Biomedical and opto-electronic applications are foreseen.