The introduction of prostate-specific antigen (PSA) testing about 3 decades ago led to the possibility of early detection of prostate cancer (PCa). Although PSA testing reduced the mortality rate, it is also associated with high risk of over diagnosis in patients with and without PCa. Despite the current drawbacks, it would be a challenge to replace PSA testing entirely. Instead, there is a need to develop parallel testing of other potential biomarkers that can complement the results from PSA tests. To address alternative biomarker sensing, this thesis highlights on the development of oligonucleotide-based biosensors for the detection of different biomarkers of PCa. Using PSA as a gold standard, the first study of this dissertation investigates the use of DNA aptamers to detect PSA using electrochemical impedance spectroscopy (EIS). The study compares 6-mercapto 1-hexanol chemistry with sulfo-betaine chemistry for the development of PSA aptasensor in terms of performance and selectivity. The second study focuses on glycoprofiling in order to complement PSA quantification as an additional information for reliable PCa diagnosis. This strategy was developed in a microfluidic channel with an optical read out using chemiluminescence. This study addresses one of the major problems of cross-reactivity with lectins in glycoprofiling, which can be solved using DNA aptamers. A third study concentrates on the development of an aptasensor for Alpha-Methylacyl-CoA Racemase (AMACR). AMACR has been reported for its high specificity and sensitivity to PCa. For the fabrication of the biosensor, a new strategy using polyethylene glycol was developed by electrochemical grafting it to a polypyrrole film. Since PCa diagnosis can be improved by looking at different biomarkers, an electrochemical platform for miRNA/DNA detection using a gold nanoparticle amplification strategy was also investigated. The sensor was fabricated using peptide nucleic acids (PNA) probes on gold electrodes. The study presents non-Faradaic EIS and amperometric techniques in order to exploit the inherent charges of nucleic acids.In conclusion, this thesis wants to serve as a potential orientation for overcoming the shortcomings of the current PCa testing and contribute towards the development of oligonucleotide-based biosensors for PCa biomarker detection and hopefully enhance the diagnosis and prognosis of PCa.
|Date of Award||15 Oct 2016|
|Supervisor||Pedro Estrela (Supervisor) & Christopher Frost (Supervisor)|
- Prostate cancer
- Electrochemical biosensors
- Electrochemical impedance spectroscopy