(179o) Spontaneous Gathering and Unraveling of DNA On Patterned Lipid Bilayer

We study the dynamic and conformational behavior of DNA absorbed on cationic supported lipid bilayer on a patterned glass surface. The pattern consists of periodic shallow trenches with the width of 10 microns and the depth of 300 nm. The trenches are separated by 10 microns. When DNA adsorbed on the lipid bilayer in a trench, it first adopts a 2-dimensional self-avoiding conformation and diffuses on the bilayer until some of its segments reach the trench wall. DNA then spontaneously gathers and unravels along the root of the trench wall within few seconds. For lambda DNA, it easily extends to more than 50% in our typical setup. This phenomenon is controlled by the competition between the electrostatic interaction and conformational entropy of DNA. We examine the influence of DNA molecular weight and the charge density of lipid bilayer on the DNA behavior, and develop a simple model to describe our observation.