This thesis describes two novel applications of scanning electrochemical microscopy
(SECM) to biological systems.
The first involves the characterisation of a novel, impedance based genomic DNA
biosensor - previously developed within the group. SECM in feedback mode was used to
interrogate a DNA-polyelectrolyte film to determine whether the changes observed by
impedance were detectable by SECM. Using the SECM micropositioning device to
pattern a carbon ink substrate, a dotted array of polyethylenimine (PEI) and single
stranded DNA (ssDNA) was fabricated. Using hexamine ruthenium chloride as the redox
couple, the array was then interrogated by a SECM area scan before and following
exposure to complementary and non-complementary DNA. Upon the exposure of the
DNA/PEI array to complementary DNA, the feedback current over the functionalised
region was observed to increase, whereas on exposure of the array to non-complementary
DNA, an increase in feedback current was also observed - but to a lesser degree.
The second SECM application described involves the use of SECM to detect protein
expression in cells. Using an established immunochemical protocol, the transmembrane
protein, CD44, expressed by cultured RT112 cells was labelled via a primary/secondary
antibody complex to horseradish peroxidase. Using hydrogen peroxide and
hydroquinone, the activity of the HRP label was subsequently detected by SECM in
feedback mode. The microelectrode tip was biased at a potential of -0.4V, a potential
sufficient for the reduction of benzoquinone - the redox active product of the HRP
catalysed reaction. The work presented represents the first application of SECM to
detecting protein expression in cells and effectively demonstrates the promise this
technique holds for immunochemical applications.
An analysis of Uniscan’s innovation network is also presented, which provides a valuable
insight into the management of such resources and how they may be orchestrated to
extract maximal innovative value for all parties involved in a collaborative relationship
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