Elongational-flow-induced scission of DNA nanotubes in laminar flow.

The length distributions of polymer fragments subjected to an elongational-flow-induced scission are profoundly affected by the fluid flow and the polymer bond strengths. In this paper, laminar elongational flow was used to induce chain scission of a series of circumference-programmed DNA nanotubes. The DNA nanotubes served as a model system for semiflexible polymers with tunable bond strength and cross-sectional geometry. The expected length distribution of fragmented DNA nanotubes was calculated from first principles by modeling the interplay between continuum hydrodynamic elongational flow and the molecular forces required to overstretch multiple DNA double helices. Our model has no-free parameters; the only inferred parameter is obtained from DNA mechanics literature, namely, the critical tension required to break a DNA duplex into two single-stranded DNA strands via the overstretching B-S DNA transition. The nanotube fragments were assayed with fluorescence microscopy at the single-molecule level and their lengths are in agreement with the scission theory.