Highly efficient binding of DNA on the sidewalls and tips of carbon nanotubes using photochemistry

The sidewalls of vertically aligned, multiwalled carbon nanotubes were functionalized using azide photochemistry, and DNA oligonucleotides were synthesized in situ from the reactive group on each photoadduct to produce water-soluble DNA-coated nanotubes. The functional DNA sites on the nanotubes were visualized from gold nanoparticles modified with complementary DNA and using TEM. The sidewall functionalization enabled further DNA-directed modification of the nanotubes' surfaces with nanoparticles. The DNA-coated vertically aligned nanotubes offer the architecture for a highly loaded three-dimensional DNA chip.