Dynamics of Semiflexible Viruses in Polyelectrolyte Solutions

The structure and dynamics of polyelectrolytes differ from those of neutral polymers. How these differences affect the transport of anisotropic particles remains incompletely understood. Here, we study the dynamics of semiflexible, rodlike M13 bacteriophage (phage) in aqueous semidilute solutions of sodium poly(styrene sulfonate) with various ionic strengths using fluorescence microscopy. Phage exhibit approximately diffusive dynamics and non-Gaussian distribution of displacements across all polymer concentrations. The phage dynamics are faster than nanospheres of the same hydrodynamic size and monotonically deviate from predictions for the diffusivity of rods based on the bulk viscosity across all polymer length scales. Available scaling theories for neutral polymers can only partially collapse dynamics as a function of normalized length scales onto a master curve. Furthermore, the non-Gaussian parameter exhibits concentration-dependent temporal evolution. These results suggest the presence of multiple diffusive modes due to the anisotropic structure of the filamentous viruses and the confining time and length scales set by polymer structure and dynamics.