Capture of unstable protein complex on the streptavidin-coated single-walled carbon nanotubes

Purification of unstable protein complexes is a bottleneck for investigation of their 3D structure and in protein–protein interaction studies. In this paper, we demonstrate that streptavidin-coated single-walled carbon nanotubes (Strep•SWNT) can be used to capture the biotinylated DNA–EcoRI complexes on a 2D surface and in solution using atomic force microscopy and electrophoresis analysis, respectively. The restriction enzyme EcoRI forms unstable complexes with DNA in the absence of Mg2+. Capturing the EcoRI–DNA complexes on the Strep•SWNT succeeded in the absence of Mg2+, demonstrating that the Strep•SWNT can be used for purifying unstable protein complexes.