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A new approach to theoretical modeling of membrane potential
|Andrzej Lewenstam 1,2,3, Witold Kucza 2,3, Tomasz Sokalski 1, Robert Filipek 2,3, Johan Bobacka 1, Marek Danielewski 2,3|
1. Abo Akademi University, Center for Process Analytical Chemistry and Sensor Technology ProSens (PROSENS), Biskopsgatan 8, Turku 00410, Finland
Existing theoretical interpretations of membrane potential used in biology and in chemistry are based on assumptions of total or local equilibrium and electroneutrality or quasielectroneutrality. This practice allows simplifying calculus; however, it does not allow access to time domain and non-equilibrium membrane potential. The paradox is in fact that non-equilibrium membrane potential is a prerequisite of biological life and majority of applications of membrane-based sensors. Many practical applications of ion-selective membrane electrodes (ISEs) are impeded simply because of lacking interpretation of variability of selectivity coefficients and detection limits over time. For this reason, we use the Nernst-Planck-Poisson (NPP) equations to pave access to the time-domain. The NPP equations allow predicting and visualizing the selectivity and the low detection limit variability over time as well as assessing the influence of other physico-chemical parameters e.g. membrane thickness, main to interfering ion concentration ratios and ion diffusibility. In this way, the conditions under which measured selectivity coefficients are true (unbiased) and detection limits can be optimized.
This work is supported by the Polish State Committee for Scientific Research via grant KBN 3 T09A 175 26, and by the Finnish Academy via the Process Chemistry Centre (PCC) at Abo Akademi University, Finland.
Presentation: Tutorial lecture at SMCBS'2007 International Workshop, by Andrzej Lewenstam
See On-line Journal of SMCBS'2007 International Workshop
Submitted: 2007-08-28 12:22 Revised: 2009-06-07 00:44