Nanodissection of single- and double-stranded DNA by atomic force microscopy

Nanodissection of single-stranded DNA (ssDNA) and double-stranded DNA (dsDNA) has been investigated by atomic force microscopy (AFM). It is found that both ss- and dsDNA can be repeatedly dissected by an AFM tip. However, a comparison study indicates that ssDNA is a little bit more easily broken by the AFM tip than dsDNA. This is supported by the fact that the time requested to break ssDNA is shorter than that of dsDNA in the same dissection procedure under the same load. Our experiment also shows that dissection of the DNA strand is very sensitive to the load applied, and a small change of the load lead to different results.