Conformational structure of an adsorbed polyelectrolyte on a nanoparticle with low conductivity in an alternating electric field

Abstract

An analytical form of the model of the quasi-equilibrium conformational structure of the units of the Gaussian chain of a polyelectrolyte adsorbed on a nanospheroid with a relatively low electrical conductivity (undoped semiconductor) polarized in an external harmonically varying quasi-static electric field with a frequency significantly lower than the plasma frequency of the nanoparticle material is proposed. Variants of the model are discussed that go beyond the scope of the quasi-static approximation, i.e., take into account the effects of delay, the manifestation of which will be noticeable in the case of sufficiently extended nanostructures. Electrically induced conformational changes of generally neutral polyampholytic polypeptides on the surface of a spherical germanium nanoparticle in a static or alternating external electric field have been studied by molecular dynamics. In a static electric field, in the case of a small distance between the charged units in the polyampholyte, a large number of macrochain loops were formed, elongated in the direction of the polarization axis of the nanoparticle. If the distance between the oppositely charged amino acid residues of the polypeptide exceeded the diameter of the nanoparticle, the charged units were mainly localized in the oppositely charged subpolar regions of the polarized germanium nanoparticle. In an alternating electric field, a girdle polyampholyte edge was formed in the equatorial region of the nanoparticle, the macrochain links of which were desorbed from the surface with an increase in the amplitude of the polarizing alternating electric field.