M.Sc Thesis


M.Sc StudentEshel Yoni
SubjectLong Range Charge Transport Across Biological Materials:
Measurements, Simulations and Applications
DepartmentDepartment of Nanoscience and Nanotechnology
Supervisor ASSOCIATE PROF. Nadav Amdursky
Full Thesis textFull thesis text - English Version


Abstract

From cellular respiration to neuron firing, electronic and ionic charge transfer are key aspects of many biological functions. Our understanding of such processes in biology and their importance is still limited, and electrical properties of biological material and biology interaction with electrical signals is studied widely. In this thesis, we combine two different projects with a common denominator of bio-related charge transfer. Our two projects will touch two aspects of the field through simulations, bacterial nanowire and conductive scaffolds for tissue engineering.

When focusing on electrons as charge carriers, up until lately, long-distance biological electron transport was considered to be at about . However, recent discoveries of bacterial nanowires revealed electron transfer along distances in the millimetric scale and with high conductivity, challenging the previously perceived long-range biological charge transfer. Accordingly, in our bacterial nanowire chapter we tackle these recent findings directly, while hypothesizing that the common incoherent electron transport might not be the predominant electron transfer mechanism across the bacterial nanowire. Our goal here is to offer a new electron transport mechanism that might explain very long-range electron diffusion across this biological material. In our simulations, we find that a mixed conductance model involving both incoherent and coherent steps can be more appropriate for the bacterial nanowire system. Better understanding of these mechanism could prove useful in improving and enhancing existing applications such as in microbial fuel cells, and biosensing.

This interface of biology and conductive materials lately entered the field of cardiac and neuronal tissue engineering, where conductive scaffold showed increased tissue growth and connectivity and support cells synchronizing, but with little understanding as to the mechanism behind this affect. Hence, even though this interesting application of conductive scaffold seems promising, without understanding this phenomenon, it will be hard to advance its use. As such, in our conductive scaffold section, we aim in deciphering the electrical interface between the conductive scaffold to the engineered tissue. We model the electrical response of cardiac and neurons cells as well as their interaction with the conductive scaffold and show specifically what is the electrical role of the scaffold in propagating the signal and bridge across large distances and scar tissue.