Abstract:
This thesis describes work focused towards the fabrication and characterisation of
immunosensor platforms for the label-free detection of analytes of importance in the
health and food industries. Due to their low unit cost and ease of fabrication, the
immunosensor market has significantly increased recently, resulting in a constant
demand for new immunosensor applications. Within this thesis, therefore, a novel
fabrication protocol is reported towards the production of immunosensor platforms for
the detection of the antibiotic, ciprofloxacin, the stroke and multiple sclerosis marker,
Myelin Basic Protein (MBP) and the ovarian cancer marker CA-125.
Initial investigations were aimed towards the electrochemical characterization of the
available electrode substrates at the onset of this research project namely, gold sputter
coated, screen-printed gold and carbon electrodes. They showed that only carbon
electrodes provide sufficiently reproducible results and thus these electrodes have
been employed for immunosensor fabrication. Due to the advantages of
microelectrodes over planar electrodes, attempts to fabricate microelectrode arrays
were also made via the ultrasonic ablation of passivated electrode assemblies.
For the site-specific immobilisation of antibodies on polymer modified surfaces
biotin-neutravidin affinity technologies were used. The fabricated immunosensors
were then interrogated upon exposure to antigen solutions utilising the technique of
electrochemical impedance spectroscopy (EIS). Changes in the obtained impedance
spectra were used to plot calibration profiles for the detection of ciprofloxacin in
buffer and in milk. Similar profiles have been plotted for Myelin Basic Protein (MBP)
and the ovarian cancer marker CA-125.
