Study of Biological Ion Channels by Using PNP/ECP Model

Ion channels are proteins embedded in the membrane of all biological cells, folded in a manner that creates nanoscopic pores that control the flow of ions in and out of the cell. All ion channels carry a highly localized distribution of permanent charge and possess specific properties (e.g., selectivity and switching) that are interesting to the device engineering community. The Poisson-Nernst-Planck (PNP) theory, also known as drift-diffusion theory, can be used to compute macroscopic current in ion channels reasonably quickly. However, PNP theory can be problematic when applied to regions of constricted volume, such as the interior of ion channels. Additionally, traditional PNP theory ignores the finite volume occupied by the ions and water molecules, as well as the non-singular distribution of charge on the ion. As a result, Coulombic screening can be overestimated, particularly in highly charged regions. The entropic effects of finite-sized ions and water molecules, and the non-singular charge distribution on the ion can be introduced into the PNP formalism by including an additional component to the electrochemical potential. The so-called excess chemical potential (ECP) represents the difference between the electrochemical potential of a real ionic solution and that of an idealized solution. The ECP terms are added to the electrostatic potential in the flux equations, yielding a modified set of PNP equations.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Electrical Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2015

Author dc:creator

• Yang, Zhicheng

Contributors dc:contributor

• Ravaioli, Umberto

• Biology, Molecular

Language dc:language

eng

Identifier

(MiAaPQ)AAI3270059

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/81021