Development of an affinity sensor for prostate cancer diagnosis
| dc.contributor.advisor | Tothill, Ibtisam E. | |
| dc.contributor.author | Uludag, Yildiz | |
| dc.date.accessioned | 2023-06-22T13:04:22Z | |
| dc.date.available | 2023-06-22T13:04:22Z | |
| dc.date.issued | 2010-11 | |
| dc.description.abstract | Prostate carcinoma is a fatal malignancy and is a major cause of death in men in the population aged 55 and over. Early diagnosis of prostate cancer is very important for successful treatment of the disease. The increase in prostate specific antigen (PSA) levels in serum above the normal limits is the primary indication of prostate malignancy; therefore, PSA is used as a biomarker for the diagnosis and prognosis of prostate cancer. To date PSA testing still dominate as the best biomarker for prostate cancer detection even though it is not prostate specific. This project aims to develop a rapid, sensitive and specific biosensor to detect prostate cancer biomarkers in order to reduce the number of people who undergo invasive examinations for diagnosis. As part of the work, alternative surface chemistry techniques were investigated to optimise the sensors immobilisation capacity, such as the use of dendrimer monolayers and surface grafting polymers. It was found that dendrimer monolayers can be used to increase the sensor surface capacity by 1.5 times for surface plasmon resonance (SPR) sensor chips but not for quartz crystal microbalance (QCM) chips. A novel polymer (UVlink) surface was also fabricated and successfully used for biomolecule immobilisation for SPR and QCM chips. The QCMA-1 prototype biosensor was applied to develop PSA detection assays. Initially an immunoassay was constructed and optimised on the QCM sensor chip. A new buffer was then formulated to eliminate 98% of non-specific binding due to human sera proteins and this enabled the PSA detection assay to be performed in 75% human serum. Since QCMA-1 instrument is a prototype, to confirm the results the PSA assay was repeated using a commercial biosensor, Biacore 3000. This newly developed method showed a limit of detection of 0.29 ng mL"1 (in 75 % serum) with a linear dynamic detection range up to 150 ng mL"1 with Au nanoparticles employed for sensitivity enhancement using both instruments. With the achieved detection limit, it is possible to use the developed QCM and SPR assays for cancer detection in patient samples. PSA detection binding data fitted to 1:1 Langmuir binding model and KD calculated as 9.46 x IQ"10 M for the assay performed with Biacore 3000 instrument and using the QCMA-1 biosensor 5.56 x 10"10 M. These results were comparable and show that the affinity between PSA and PSA-capture antibody is in the region of 10'10 M and that QCMA-1 assay results are compatible with Biacore 3000 assay results. In the study incorporation of fPSA, cPSA and PSMA immunoassays to the prostate cancer detection test was also considered. However, the commercial available antibodies were formed to have low affinity for these markers. Patient samples collected from Bedford Hospital NHS Trust and control samples collected from Cranfleld University staff were tested and it was found that the developed QCMA-1 test clearly discriminates the PSA level of patients from the controls. A second biosensor platform based on label-free interdigitated capacitive sensing principle was also employed in the study. Interdigitated electrode (IDE) arrays were fabricated with conventional microelectronics-micromachining technologies on silicon wafers. Later IDE arrays were utilised for the detection of PSA using an LCR meter. This new prototype enabled capacitance reading of individual capacitors in turn and also enabled the detection to be performed in buffer solution. Antigen binding assays were developed to capture the PSA molecule in buffer solutions achieving a detection limit of 15.6 ng mL"1 with a linear dynamic detection range of 15.6 - 250 ng mL"1 PSA | en_UK |
| dc.identifier.uri | https://dspace.lib.cranfield.ac.uk/handle/1826/19852 | |
| dc.language.iso | en | en_UK |
| dc.rights | © Cranfield University, 2015. All rights reserved. No part of this publication may be reproduced without the written permission of the copyright holder. | |
| dc.title | Development of an affinity sensor for prostate cancer diagnosis | en_UK |
| dc.type | Thesis | en_UK |
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