The emergence of MNAzymes (Multi-component nucleic acid enzymes) provides a new approach for detection of target analytes in various applications. In this thesis, three novel MNAzyme-based methodologies were developed to expand the range of the applications of MNAzymes. MNAzymes can be coupled with DNA or RNA ligands called aptamers to generate an apta-MNAzyme system, which can be used for the detection of non-nucleic target analytes such as small molecules and proteins. Direct detection using apta-MNAzyme system is performed in a format, which was isothermal, fluorescent, rapid, and requires no protein enzymes. Apta-MNAzymes can be coupled with a signal amplification cascade to increase the sensitivity of the reaction. Another MNAzyme-based methodology termed truncated MNAzyme arm system was developed to discriminate the presence of a single base mismatch of two closely related sequences. The system employs a partzyme with a truncated sensor arm and a stabiliser oligonucleotide that binds adjacently to the truncated sensor arm to stabilise the active MNAzyme structure. Truncated MNAzyme real-time PCR system is capable of discriminating the presence of a single base mismatch in a target DNA with high specificity and sensitivity (down to approximately 10 gene copies). The generic nature of the system enables simultaneous detection of three SNP targets in a multiplex format. MNAzymes was also investigated with various strategies to discriminate DNA sequences that are either methylated or unmethylated. In this thesis, bisulphite-treated DNA samples present in as low as 0.032 % of methylated DNA in a background of unmethylated DNA were discriminated using MNAzyme real-time methylation specific PCR (MSP) system. Furthermore, the presence of 5-methylcytosines in a target sequence increases the melting temperature of the duplex DNA. This was exploited further to directly discriminate DNA methylation status of target sequences using the truncated MNAzyme arm system without the need for bisulphite modification. Findings in this thesis have broadened the scope of MNAzymes as versatile tools for many possible applications and flexible alternative to the current technologies.
| Identifer | oai:union.ndltd.org:ADTP/258139 |
| Date | January 2009 |
| Creators | Suwandi, Ronald, Biotechnology & Biomolecular Sciences, Faculty of Science, UNSW |
| Publisher | Publisher:University of New South Wales. Biotechnology & Biomolecular Sciences |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Rights | http://unsworks.unsw.edu.au/copyright, http://unsworks.unsw.edu.au/copyright |
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