| dc.description.abstract | Polypyrrole (PPy) is a conjugated polymer that displays special electronic properties
including conductivity. It may be electrogenerated with the incorporation of any anionic
species including negatively charged biological molecules such as proteins and
polysaccharides. For this thesis, variously loaded-PPy films were prepared on gold
sputter-coated coverslips. The growth and characteristics of epithelial cells, namely
keratinocytes, were studied on these films by microscopy, biochemical assay,
immunocytochemistry and electrochemical impedance spectroscopy.
Keratinocyte viability was found to be PPy-load dependent. For chloride, polyvinyl
sulphate, dermatan sulphate and collagen-loaded PPy films, polycarbonate and gold,
keratinocyte viability, as assessed by the AlamarBlueTM assay, was respectively 47%,
60%, 88% and 23%, 75% and 61% of tissue culture polystyrene controls after 5 days.
This was found to require a previously unreported polymer washing step prior to cell
seeding due to the observed toxicity of untreated films. Keratinocytes stained positive
for proliferation (PCNA), suprabasal differentiation (K10) and hyperproliferation (K16)
markers although cell morphology was poor for organotypical cultures on dermatanloaded
PPy compared with de-epidermalised dermis. Cell-induced impedance changes
were detected in a three-electrode format over PPy modified electrodes. Results
obtained showed the effects of cell density, cell type and monitoring frequencies. In
particular, it was seen that lower cell densities could be detected on PPy compared to
unmodified gold electrodes. Keratinocyte confluence as determined by impedimetric
analysis was reached more rapidly on PPy than bare gold in agreement with
AlamarBlueTM measurements. Electrical equivalent circuit analysis using parameters
whose contributions may be directly mapped to intracellular and intercellular spaces,
and membrane components suggested that the technique can be extended to cell
morphology discrimination.
This work shows that PPy biocomposites are attractive candidates for tissue engineering
applications since they may incorporate biomolecules and are electrically addressable
with the potential to both direct and report on cell activities. | en_US |
