Preparation and Atomic Force Microscopy of Quadruplex DNA

The purpose of this chapter is to provide detailed instructions for the preparation and atomic force microscopy (AFM) imaging of linear chains of quadruplex DNA (a.k.a. “G-wire DNA”). Successful self-assembly of long chain quadruplex DNA requires pure concentrated guanine-rich oligonucleotide sequence (GROs) and monovalent cations in a growth buffer. AFM imaging of individual G-wire DNA strands requires many carefully monitored steps, including substrate preparation, G-wire concentration, adsorption onto substrate, rinsing, drying, appropriate selection/use of imaging probes, and dry atmosphere imaging conditions. Detailed step-wise instructions are provided.