(543e) Effective Surface Diffusion of a Polyelectrolyte within Nanoscale Confinement

Authors: 
Morrin, G. T. - Presenter, University of Colorado
Kienle, D., University of Colorado
Weltz, J. S., University of Colorado Boulder
Traeger, J., University of Colorado, Boulder
Schwartz, D. K., University of Colorado Boulder
Intermittent (“hopping”) surface diffusion of poly-L-lysine in a nanoslit was studied using single-molecule tracking microscopy. Three surface chemistries were employed to understand the interplay of long-range electrostatic attraction and short-range interactions: an amine-functionalized silica surface, an oligo(ethylene oxide) (OEG) modified surface, and an equally mixed surface. Diffusion increased rapidly with slit height until saturating for values <30 nm. While diffusion at a semi-infinite interface was significantly faster for OEG surfaces, the diffusion increased most rapidly with slit height for amine-functionalized surfaces, resulting in surface diffusion that was virtually independent of surface chemistry in gaps <15nm. Kinetic Monte Carlo simulations, using parameters obtained empirically from diffusion at a single interface, suggested that these trends were primarily due to strong H-bonding interactions between PLL and amine surface ligands, which led to increased rates of re-adsorption after hops and longer waiting periods between flights, and that long-range electrostatic attraction had a minor influence.