Physics (Internal)

DNA translocation, diffusion and unzipping through a Nanopore: The physics of polymers in a highly confined space

This event is part of the Physics Department Colloquia Series.

Many biological processes involve linear translocation of long biopolymers, such as DNA or RNA through nanoscle pores. Examples are phage infection, bacterial conjugation, etc. We study the translocation dynamics of poly-nucleic acids through biological pores, as well as artificial pores, in vitro. An electrical field is used to “thread” the biopolymers through a nanoscale pore, while the ion current flowing through the pore is used to probe the system. Using a dynamic voltage control, we can rapidly manipulate the electric field (and hence the force) applied on the DNA, while it occupies the pore. This allows us to study translocation dynamics with or without drift, and to use the system to probe DNA-DNA or DNA-protein interactions. We find that the translocation kinetics is sequence-dependent due to strong interactions between the channel and the DNA. More surprisingly, directionality plays an important factor in the DNA motion, even for homo-polymers. Nanopore physics is an emerging field, which has begun to impact biophysics and biotechnology, with applications for ultra fast DNA sequencing and DNA-protein analyses.