DNA molecular configurations in flows near adsorbing and nonadsorbing surfaces

We investigate experimentally lambda-phage and T2-coliphage DNA molecules near both nonadsorbing glass and adsorbing 3-aminopropyltriethoxysilane (AP-TES)coated glass surfaces in a simple steady shearing flow generated by a torsional flow cell. The DNA molecular deformations near the surface are found to be considerably weaker than in bulk flow at the same shear rate. This affects the DNA molecule's deposition and stretching on the adsorbing surface. Surprisingly, for a simple shearing flow in the torsional shearing device, the observed stretch, for molecules both near (< 10 mu m) the surface and adsorbed to it, is much less than predicted by simulations.