Single-stranded DNA insertion into single-walled carbon nanotubes by ion irradiation in an electrolyte plasma

The inside modification of single-walled carbon nanotubes using a single-stranded DNA is demonstrated. In this method, we regard DNA solution as a plasma, i.e., an electrolyte plasma. A direct current electric field is applied to the electrolyte plasma containing DNA negative ions in order to irradiate the single-walled carbon nanotubes with DNA ions. In addition, a radio frequency electric field is superimposed to the plasma to change the conformation of DNA ion molecules from random-coiled to stretched. DNA negative ion irradiation can be controlled by varying direct current electric field and irradiation time. In addition, transmission electron microscopy and Raman scattering spectrum analyses reveal that DNA is found to be encapsulated in the single-walled carbon nanotubes.