Single-walled carbon nanotubes/DNA hybrids in water are highly stable

Unbound double-stranded DNA (dsDNA) was removed from an aqueous solution (solution 1) of dsDNA-solubilized single-walled carbon nanotubes (SWNTs) using size-exclusion chromatography (SEC). The SEC chromatogram of solution 1 showed two separated peaks, and the earlier eluent fraction was separated into four size-separated fractions, fr1–fr4, in which individually solubilized SWNTs were found to exist. The stability of the DNA/SWNT hybrids was evaluated by the re-injection of fr1–fr4. It was found that the chromatograms of fr1–fr4 were identical to those of the original ones even after storage for one month, indicating the high stability of the dsDNA/SWNT hybrids in water.