Stretching single-stranded DNA on a surface

A sufficiently long strand of DNA bends and balls up, like any other polymer longer than its persistence length. The ability to stretch a DNA molecule lengthwise on a substrate has garnered a great deal of attention in the past several years. There has been notable success in stretching double-stranded DNA (dsDNA), but it is more difficult to stretch single-stranded DNA (ssDNA), both because of the very short persistence length and because it is very "sticky," and attaches nonspecifically to surfaces. In this issue of Nano Letters, Woolley and Kelly present a new method for stretching single-stranded DNA strands on surfaces.