Abstract:
The thesis describes the development of generic platforms for labeless transduction of
binding events. A particular application of the project is the labeless detection of
biochemical markers for stroke, specifically transient ischemic attack, to facilitate rapid
diagnosis and subsequent introduction of appropriate therapy within the required
three-hour time frame. Novel biocomponents are under development for detection of
these biochemical markers, and further demonstration of the generic nature of the
technologies being developed will be realised via the use of a library of monoclonal
antibodies as capture biocomponents.
This work forms part of an investigation into labeless affinity immunosensor detection
via impedimetric transduction utilising the technique of electrochemical impedance
spectroscopy (EIS). Novel microelectrode arrays were fabricated by the sonochemical
ablation of a homogeneous insulating layer of poly(o-phenylenediamine) exposing
discrete areas of an underlying screen-printed conductive substrate. The receptor
biocomponents are then subsequently coupled to the transducer by either
electropolymerised entrapment or non-covalent affinity within and/or at the surface of
conducting polymer ‘mushroom’ shaped protrusions for site-specific immobilisation.
Upon exposure to a range of concentrations of antigen analyte solution, complex plane
impedance analyses are used to relate the differing redox states of the polymer to possible
charge transfer and / or related mechanisms between the immobilised antibody / antigen
analyte and the polymer. Results show that signal differentiations were obtained, for a
number of antibody / antigen species over a range of concentrations of clinical relevance
(ng-pg/mf1), suggesting that the techniques employed offer a viable approach towards the
labeless quantification of biochemical markers of transient ischemic attack (TIA).
