Random Walks in Disordered Environments: Membrane-Induced Confinement of DNA*

Understanding the conformation and dynamics of DNA in nanoslit structures is a topic of long-standing interest in the physics of nanoconfined polymers, yet introducing molecules into the most confined (sub 20 nm thick) structures is very challenging. Here we use a pneumatically-actuated membrane device to sandwich single DNA molecules between a flexible nitride flap and glass nanochannel floor, forcing the molecules into a degree of confinement limited only by the intrinsic roughness of the channel surfaces. In these environments the molecule undergoes a self-avoiding random walk in the disordered environment created by the surface roughness. We study single-molecule dynamics and conformation as a function of root-mean-square surface roughness and imposed confinement.