Molecular dynamics simulations have been employed to study the unique features of small molecule diffusion through various aqueous polyelectrolyte solutions. These simulations have helped elucidate our previous experimental studies of rhodamine B (RB) and rhodamine 6G (R6G) diffusion in various solutions of both poly(sodium 4-styrenesulfonate) (PSS) and poly(diallyldimethylammonium chloride) (PDDA) using single-molecule fluorescence correlation spectroscopy. We have simulated RB and R6G diffusion as a function of several solution variables, including polyelectrolyte chain length, polyelectrolyte concentration, salt concentration, salt type, and type of simulated water. Simulations were run using the GROMACS software, and efforts were made to adequately reproduce experimental polyelectrolyte dynamics in water. Experimentally, the charge on a diffusing small molecule causes interesting interactions with the charged polyelectrolyte chains. We have tested these electrostatic effects by observing the differences between the cationic R6G and the zwitterionic RB.

Simulations of small molecule diffusion in polyelectrolyte solutions

253rd National Meeting (2017)

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