Deposition and Characterization of Extended Single-Stranded DNA Molecules on Surfaces

We have devised an approach for generating well-extended, surface deposited, single-stranded DNA molecules having minimal intramolecular base-pairing. This method depends on careful control of the mica surface charge, appropriate selection of the ionic strength of the DNA solution, and controlled translation of a droplet of DNA solution along the surface. We have shown the general applicability of this technique by elongating ΦX174, M13mp18, and λ single-stranded DNA on mica followed by imaging with atomic force microscopy. We have further demonstrated the feasibility of more elaborate, multistep surface preparations by aligning λ double-stranded DNA and ΦX174 single-stranded DNA in orthogonal directions on the same substrate.