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| Home > Publications database > Clustering and dynamics in Q2D dispersions of proteins with competing interactions |
| Conference Presentation (After Call) | FZJ-2022-04922 |
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2022
Abstract: Dispersions of globular proteins or colloids with competing short-range attractive (SA) and long-range repulsive (LR) interactions exhibit a rich phase behavior with a variety of different cluster phases. While three-dimensional SALR dispersions have been intensely studied also regarding their cluster dynamics, little is known about the structure and dynamics of quasi-two-dimensional (Q2D) dispersions. The SALR particles in a Q2D dispersion form a planar monolayer inside the bulk fluid, with their centres confined to in-plane Brownian motion. The interplay of Q2D motion, SALR direct interactions and solvent-mediated hydrodynamic interactions (HIs) give rise to peculiar effects such as anomalously enhanced collective diffusion. Using Langevin dynamics simulations, we have determined the generalized phase diagram, and cluster shape and size distributions of a generic Q2D model dispersion of SALR particles. The particles in the monolayer are described as Brownian spheres interacting via short-range attractive generalized Lenard-Jones and long-range repulsive screened Coulomb potential contributions. These interactions apply, e.g., to protein solutions under low-salinity conditions. Additionally, in an elaborate multiparticle collision dynamics (MPC) simulation study, we explored hydrodynamic and direct interaction effects on the Q2D translational and rotational particles diffusion. The MPC study covers a broad range of correlation times, from very short times where the particle dynamics is non-instantaneously affected by sound propagation and transversal momentum diffusion in the solvent, to long times where HIs are fully developed. We analyzed the concentration dependence of collective diffusion at different wavenumbers, in conjunction with mean-squared displacements and real-space van Hove functions characterizing self- and collective diffusion, and non-Gaussian dynamics. To reveal the development of inter-particles HIs by multiple scattering of sound and vorticity diffusion, we examined velocity self- and cross-correlations in conjunction with associated time-dependent hydrodynamic functions.
Keyword(s): Polymers, Soft Nano Particles and Proteins (1st)
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