Field-Induced DNA Dynamics

In keeping with our interests in electric-field-induced dynamics (see PDLC studies), we recently undertook investigations of the field-induced reorientation dynamics of short, dye-labeled double stranded DNAs attached to glassy carbon electrode surfaces.[86] This work was done in collaboration with Jun Lis group and his student Qin Li. Our work was built upon extensive studies of similar dynamics on gold electrodes performed by others. Over the long term, the goal is to investigate DNA dynamics at the ends of vertically-aligned carbon nanofibers produced by the Li Group. However, our initial studies showed that the DNA dynamics (detected by distance-dependent dipole-electrode fluorescence quenching of the dye) was more complicated than previously reported. We found that the overall response of the DNA was as expected: the DNA orients perpendicular to the surface at negative potentials and parallel to the surface at positive potentials. Interestingly, the DNA also appears to relax from its initial orientation on a ~ 1 sec timescale after initial potential switching. We hypothesize that this slow relaxation is due to direct participation of DNA in initial charging of the double layer, with diffusive exchange of ions from solution allowing for later, slow orientational relaxation. Electrical double layer dynamics in the presence of highly-charged, surface-bound polyelectrolytes remain largely unexplored. It is likely that none of the data reported in the literature were acquired under appropriate conditions to detect such relaxation phenomena.

Reference numbers refer to articles in the Higgins Group publication list