Noncontact-AFM imaging of molecular surfaces using single-wall carbon nanotubetechnology

Abstract

Single-molecule imaging at nanometre resolution using noncontact AFM has been appliedto image a protein complex on mica using single-wall carbon nanotube (CNT) technology.Hydrated RNA polymerase (RNAP)–DNA complex was imaged using constant-amplitudetapping mode AFM. CNT tips (1–2 nm diameter) prepared by chemical vapour phasedeposition were mounted onto standard Pt/Ir coated AFM tips. The effectiveness of theCNT tip scanning was tested by imaging the profile of an RNAP–DNA complex.The results demonstrate the merits of high-resolution carbon nanotube nc-AFMscanning and suggest that CNT tips may provide a general tip–surface referencestandard for defining tip–surface interactions on molecular-bonded organic surfaces.