Сonformational structure of polyampholytes and polyelectrolytes on the surface of a longitudinally polarized gold spherocylinder

Abstract

Conformational changes in generally neutral polyampholytic, as well as uniformly charged macrochains, polypeptides adsorbed on the surface of a longitudinally polarized gold spherocylinder—a cylindrical nanorod with spherical ends—were studied. An analytical model of the equilibrium structure of adsorbed macrochains on the surface of a polarized spherocylinder is presented, highlighting the entropy and field factors of the radial-angular distribution of link density. In the course of molecular dynamics simulation, the radial distributions of the density of polypeptide atoms in the central cylindrical part of the nanorod, as well as on its terminal hemispheres, were calculated. In addition, the distributions of the linear density of polypeptide atoms along the axis of the nanorod were calculated. A dumbbell-shaped polyampholyte edge was formed on the surface of the polarized nanorod, dense in the extended central cylindrical part and loose at the ends of the nanorod. There was also a shift of the macromolecular edge from the units of a uniformly charged polypeptide to the oppositely charged end of the nanorod, on which this polyelectrolyte edge swelled.