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Charges and charge regulation - Rudi PODGORNIK

University of Ljubljana, Slovenia


LPS Moyen Amphi

I will present some recent developments in dealing with dissociable charge groups on solvent exposed surfaces of macromolecules. This applies to bulk protein solutions as well as proteinaceous aggregates such as viral shells and enzymatic nanocontainers, providing scaffolding and compartmentalization for chemical engineering on the nano-scale. Charge regulation alters the behavior of chargeable colloidal systems by fundamentally modifying the standard PB (Poisson-Boltzmann) paradigm. I will describe several of these modifications : (i) alterations of not only in the net charge but also in the direction and strength of all higher multipoles of single proteins ; (ii) invalidating the usual assumptions of multipolar expansion in ionic solutions ; (iii) emergence of fluctuational Kirkwood-Schumaker interactions ; (iv) spontaneous spatial symmetry breaking of electrostatic fields of charge-regulated macromolecules, consequently contradicting one of the fundamental assumptions of the PB theory ; (v) charge regulation of complex fluids with mobile macro-ions leads to positional dependence of the effective charge of the macro-ions and a non-monotonic dependence of the effective Debye screening length. These new developments embed the PB paradigm into an entirely new perspective.

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