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PhD

In my PhD, I have investigated ways of using novel electrochemical techniques to study biophysical processes. I have also used finite element method (FEM) simulations to model my experimental systems to gain a greater understanding of these processes.

A New Approach for the Fabrication of Microscale Lipid Bilayers at Glass Pipettes: Applications for Passive Permeation Visualization

This project combines electrochemical techniques with finite element method (FEM) simulations to study the permeation of weak acids across membranes. Cell membrane permeation is an interesting process to study as it is crucial to the passage of drug molecules across the blood-brain barrier and into general circulation. We are using weak acids as a model for membrane permeation since many drug molecules fall into this class. We have developed a new method for the fabrication of extremely stable lipid bilayers at glass micropipets, and coupled with confocal microscopy, the permeation of weak acids can be visualised. With the aid of FEM simulations, the fluorescence profiles can be modelled to extract permeation coefficients for each of the weak acids.

thing

Experimental setup for permeation experiments and example fluorescence profile from confocal imaging


Scanning Electrochemical Cell Microscopy (SECCM) imaging of individual single-walled carbon nanotubes (SWNTs)

Within the Electrochemistry and Interfaces group, there is a strong emphasis on the development of new electrochemical imaging techniques. One of these techniques which has yielded a great deal of information is Scanning Electrochemical Cell Microscopy (SECCM). This technique implements a dual barrel theta capillary as a mobile electrochemical cell, and as this probe is scanned along the surface, the electrochemical response can be recorded. With this technique we have been able to image individual aligned single-walled carbon nanotubes (SWNTs) and examined their activity along the length of the tube and the voltammetric response to a number of redox mediators, including biological molecules such as serotonin and dopamine.

seccm

SECCM setup and image of an individual SWNT with serotonin


FEM Simulations to Extract Kinetic Information

I have developed a number of FEM simulations which have been used by other members of the group. I have modelled the response of a polycrystalline boron doped diamond electrode as it is imaged using intermittent-contact scanning electrochemical microscopy, which has been published in the following paper:

Electrochemical Mapping Reveals Direct Correlation between Heterogeneous Electron-Transfer Kinetics and Local Density of States in Diamond Electrodes
H. V. Patten, K. E. Meadows, L. A. Hutton, J. G. Iacobini, D. Battistel, K.McKelvey, A. W. Colburn, M. E. Newton, J. V. Macpherson and P. R. Unwin, Angew. Chem. Int. Ed., 2012, 51 (28), 7002-7006.

bdd

FEM simulation domain and (a) FE-SEM image, (b) Raman map, (c) IC-SECM image and (d) kinetic rate constant map.