Theoretical investigation of polarizability of soft biological particles
Naga Neehar Dingari (MIT ), Cullen Buie (Massachusetts Institute of Technology)
Electrohydrodynamics and electrokinetics of fluid systems
Mon 10:45 - 12:15
Barus-Holley 161
We present a detailed theoretical model to investigate the effect of ‘soft’ polyelectrolyte layers on the polarization of biological particles such as bacteria. Building off of the work done by Zhao et.al[1], we model the soft layer of biological particles including dissociation of ionogenic charged groups and specific interactions with the background electrolyte. We model ionic transport around the soft particle with a modified Poission-Nernst-Plank equation for soft particles[2]. The fluid flow around the particle is modeled by a modified Stokes equation accounting for permeability of the soft layer. The results demonstrate an interesting interplay between soft layer conductivity (which is a function of pH, pKa of ionogenic groups, and bulk electrolyte concentration) and double layer conductivity (which is a function of bulk electrolyte concentration) on the polarizability of soft biological particles. As a consequence of our analysis, we highlight electrolytic and pH conditions favorable for manipulation of biological particles using dielectrophoresis and electrophoresis depending on the nature of their soft layers. [1] Uppapalli, S.; Zhao, H. Langmuir: the ACS journal of surfaces and colloids 2012, 28, 11164–72. [2] Duval, J. F. L.; Ohshima, H. Langmuir: the ACS journal of surfaces and colloids 2006, 22, 3533–46.