Electrophoresis of a soft particle with a hydrophobic rigid core decorated with a soft-step and partially ion-penetrable polymer layer

On the basis of flat-plate formalism, we present an analytical theory for the electrophoresis of soft particles consisting of a hydrophobic inner core decorated with a layer of inhomogeneously distributed polymer segments. Biocolloids or bio-compatible drug delivery vehicles often carry the non-wettable or hydrophobic inner core. In addition, due to electrostatic swelling/shrinking processes, a spatially varying heterogeneity can be seen in the monomer distribution as well as charge properties of the peripheral polyelectrolyte layer (PEL). We adopt the soft-step function to model the chemical and structural anisotropy of the peripheral PEL. In addition, the PEL for the aforementioned bio-systems immersed in aquatic microenvironment often induces dielectric gradient-mediated ion partitioning effect, which in turn leads to the PEL to be partially ion penetrable. Within the Debye-Huckel electrostatic framework, we derive a general expression for electrophoretic mobility of a soft particle considering the combined impacts of hydrophobicity of the inner core, inhomogeneously distributed segment distribution accompanied by chemical heterogeneity and ion partitioning effect. We further derived asymptotic limits of the more generic results detailed here under several electrostatic and hydrodynamic conditions. Published under an exclusive license by AIP Publishing.

Automated summary

Based on the flat-plate formalism, this paper presents an analytical theory for electrophoresis of soft particles with a hydrophobic inner core decorated with a layer of polymer segments. By adopting the soft-step function, the chemical and structural anisotropy of the peripheral polyelectrolyte layer is modeled, considering the ion partitioning effect. A general expression for electrophoretic mobility is derived, considering the impacts of inner core hydrophobicity, inhomogeneous segment distribution, and ion partitioning effect. Asymptotic limits are also derived under various electrostatic and hydrodynamic conditions.