Advanced Technologies in Rapid and Multiplex Detection of Nucleic acid

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Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Environment and Sc
Science, Environment, Engineering and Technology
Nucleic acids are key macromolecules of living organisms transferring genetic inheritance from one generation to the next. From how a living individual is created to how it interacts with external factors, all and all, can be found in the nucleic acid sequences inside every single cell of every organism. Therefore, the analysis of nucleic acids sequences is a critical capability for cancer and pathogen diagnoses, genotyping, and disease monitoring. To date, numerous methods have been used to detect both characterised and uncharacterised mutations and sequence variations. However, the detection of low amounts of mutant genes in the presence of high levels of wildtype sequences is still a challenge, and existing technologies has room for improvement. The classical approaches for nucleic acid detection and analyses mainly include DNA sequencing and the polymerase chain reaction (PCR). Although these methods with high analytical performance and reliability have facilitated the interrogation of the nucleic acids, some key obstacles such as the need of labelling, high costs for routine clinical use, slow turnaround time for giving results, the complexity of operation, and the inability to dually detect the genetic mutation in one step have limited their applications. To avoid drawbacks of the traditional approaches, a number of chip-based methods leverage electrochemical readouts or microfluidics to identify nucleic acids. However, there is still an unmet need for a less complex, rapid, low-cost, sensitive and accurate method to enable nucleic acid analysis even in resource-poor settings. The overall objective of this PhD thesis is to develop simple, inexpensive and accurate platforms for nucleic acid evaluation. To achieve the aforementioned goal, the first attempt was to develop a lab-on-a-chip platform for cancer diagnosis by detection of circulating tumor nucleic acids (ctNAs) in plasma samples of cancer patients. ctNAs are fragmented DNA released from cancerous cells