Successive Azide and DNA Functionalization for Reversible and Controlled Association of Single-Wall Carbon Nanotubes

A bifunctional linker for robust and straightforward functionalization of carbon-based nanomaterials, featuring an azido group at one end and a diazonium group at the other, is synthesized and used to introduce azido groups on the sidewalls of (6,5)-single-wall carbon nanotubes. The versatility of the azido groups as reactive handles is demonstrated by further functionalization with 6-carboxyfluorescein and oligonucleotides through copper-free strain-promoted azide-alkyne cycloaddition, ideal for biological applications. UV melting profiles and atomic force microscopy (AFM) images of mixtures of nanotubes functionalized with complementary oligonucleotide strands are consistent with hybridization-controlled bundling-debundling equilibria.