Diameter-Dependent Competitive Adsorption of Sodium Dodecyl Sulfate and Single-Stranded DNA on Carbon Nanotubes.

The equilibrium compositions of coatings on single-wall carbon nanotubes were spectroscopically deduced for samples dispersed in dilute sodium dodecyl sulfate (SDS) and then exposed to low concentrations of ssDNA oligomers. With all studied oligomers, displacement of the SDS tended to occur at lower ssDNA concentrations for smaller diameter nanotubes than for larger diameter ones. However, the behavior varied significantly with oligomer.

Kinetics of Single-Wall Carbon Nanotube Coating Displacement by Single-Stranded DNA Depends on Nanotube Structure.

Time-resolved fluorescence spectroscopy has been used to study the displacement of adsorbed sodium dodecyl sulfate (SDS) from the surface of single-wall carbon nanotubes (SWCNTs) by short strands of single-stranded DNA. Intensity changes in near-infrared emission peaks of various SWCNT structures were analyzed following the addition of six different (GT) oligomers ( from 3 to 20) to SDS-coated nanotube samples. There is a strong kinetic dependence on the oligomer length, with (GT) giving an initial rate more than 300 times greater than that of (GT).