High-Resolution Scanning Tunneling Microscopy Imaging of Biotin–Avidin–G4-DNA Molecules

The morphological structure of G4-DNA wires having four parallel strands, made by a novel synthesis method, was revealed by high-resolution scanning tunneling microscopy (STM). This imaging technique is a unique alternative to obtain information on the molecular structure of these wires in the absence of X-ray and NMR data. Imaging reveals a periodic structure seen as repeating “bulbs” along the molecule. The bulbs correspond to the helical structure of the molecules. The STM imaging shows a molecular chain structure. This structure exhibits an average periodicity of 3.5 nm and an average molecular apparent height of 1.4 nm.