Positive zeta potential of a negatively charged semi-permeable plasma membrane

Abstract

The negative charge of the plasma membrane (PM) severely affects the nature of moieties that may enter or leave the cells and controls a large number of ion-interaction-mediated intracellular and extracellular events. In this letter, we report our discovery of a most fascinating scenario, where one interface (e.g., membrane-cytosol interface) of the negatively charged PM shows a positive surface (or ζ) potential, while the other interface (e.g., membrane-electrolyte interface) still shows a negative ζ potential. Therefore, we encounter a completely unexpected situation where an interface (e.g., membrane-cytosol interface) that has a negative surface charge density demonstrates a positive ζ potential. We establish that the attainment of such a property by the membrane can be ascribed to an interplay of the nature of the membrane semi-permeability and the electrostatics of the electric double layer established on either side of the charged membrane. We anticipate that such a membrane property can lead to such capabilities of the cell (in terms of accepting or releasing certain kinds of moieties as well regulating cellular signaling) that was hitherto inconceivable.

Coating for preventing nonspecific adhesion mediated biofouling in salty systems: Effect of the electrostatic and van der waals interactions

“…This might not always be true and the effects of semi‐permeability of LBL membrane of the microorganism will also change the overall ion distribution in the entire cytosol‐LBL‐electrolyte system. However, the theoretical framework, following our previous studies [19–22, 49–52], is robust enough to easily account for these changes and provide a new estimation of the effect of the electrostatic‐vdW interactions in determining the anti‐biofouling action of the coating. Finally, for the calculation of the Hamaker constant, we have assumed identical properties of the LBL for all the microorganisms.…”

Electrophoresis of Liquid-Layer Coated Particles: Impact of Ion Partitioning and Ion Steric Effects

“…Besides, Grosse and Shilov, and Pedrosa et al, studied the electrophoresis of colloidal particles in weak electrolyte solutions. The knowledge of electrostatic properties of NPs is important to understand the electrostatic interaction of NPs and the biological system, , performance and efficacy of the functionalized NPs in drug delivery system, − colloidal stability, and to prevent agglomeration. , …”

Electrostatics and Interactions of an Ionizable Silica Nanoparticle Approaching a Plasma Membrane

“…The vast majority of the prior investigations on the PM–NP interactions have focused on the forces and the mechanisms during the contact (through receptor–ligand interaction) between the PM and the NP, − with less emphasis on the forces at play during the approach of the NP towards the PM. In a series of the recent studies, Das and co-workers established that this approach of the NP towards the PM is dictated by an interplay of the repulsive electrostatic and the attractive van der Waals (vdW) interactions. , The electrostatic repulsion is dictated by the electric double-layer electrostatics of the PM − and the manner in which the finite surface charge of the PM interplays with the NP properties (e.g., its original surface charge and the permittivity) and the extracellular electrolyte concentration to trigger a finite electrostatic potential (of the same sign as the membrane surface charge) at the surface of the approaching NP. The findings from these calculations unraveled (a) the design criterion for the selection of the length of the ligand to ensure successful receptor–ligand interactions overcoming the electrostatic repulsion, (b) the possibility of ensuring simultaneous promotion of specific adhesion and prevention of nonspecific adhesion using biomimetic NPs, and (c) the role of electrostatics in ensuring the possible nonspecific adhesion of the NPs to PMs with larger stiffnesses (e.g., PMs rich in cholesterol).…”

“…Additionally, we also demonstrate that the presence of the NP in the vicinity of PM leads to the most nonintuitive nonisopotentiality (i.e., a gradient in the electrostatic potential) across the PM, despite the PM being a fully permeable one. Such nonisopotentiality is typically witnessed for a semipermeable membrane and not for a permeable one. , The presence of such nonisopotentiality would cause a large difference in the disjoining pressure across the PM, which has the potential for the PM rupture and cell apoptosis. Overall, these findings bring to surface several key issues related to noncontact electrostatic interactions between the PM and an approaching ionizable silica NP that have so far been overlooked but holds the potential of improving the design of silica-NP-based targeted delivery of drugs, genes, and imaging agents.…”