Noncontact-AFM imaging of molecular surfaces using single-wall carbon nanotube technology

Single-molecule imaging at nanometre resolution using noncontact AFM has been applied to image a protein complex on mica using single-wall carbon nanotube (CNT) technology. Hydrated RNA polymerase (RNAP)–DNA complex was imaged using constant-amplitude tapping mode AFM. CNT tips (1–2 nm diameter) prepared by chemical vapour phase deposition were mounted onto standard Pt/Ir coated AFM tips. The effectiveness of the CNT tip scanning was tested by imaging the profile of an RNAP–DNA complex. The results demonstrate the merits of high-resolution carbon nanotube nc-AFM scanning and suggest that CNT tips may provide a general tip–surface reference standard for defining tip–surface interactions on molecular-bonded organic surfaces. (Some figures in this article are in colour only in the electronic version)