PEC bioanalysis represents a unique and dynamically developing methodology that offers an elegant route for sensitive biomolecular detection. Building on the principle of EC analysis, PEC biosensors harness the unique properties of optically active species to enhance analytical performance. Owing to the current based outputs evolved in both PEC and EC bioanalysis, they can be miniaturized and potentially integrated with handheld and portable analyzers, making them uniquely positioned as tools to build effective POC diagnostics.
The commercialization of PEC technology for building POC diagnostics, however, heavily depends on enhancing the stability of the photoelectrodes upon repeated use, lowering the limit-of-detection (LOD) of the PEC biosensor used, enhancing the efficiency of signal transduction and the ability of the device to detect minute amounts of biomolecular target in complex biological matrices. In order to address these constraints, we first developed a new solution-based strategy integrating inorganic semiconductive species (titanium dioxide) in an organic framework to construct photoelectrodes with enhanced signal baselines and adequate stability for the cyclic measurements required in biosensing.
These transducers were subsequently used to investigate the interaction mechanisms (wavelength dependency, coverage density dependency and spatial dependency) between plasmonic NPs (Au) and the photoelectrodes —chosen as model materials—with the goal of enabling predictive dual-signal modulation and enhanced limit-of-detection in PEC biosensors. The understanding gained was used to design a dual-signal PEC transduction strategy—operated at a single excitation wavelength and on a single electrode—to detect nucleic acid sequences in urine without direct target labeling, target amplification or target enrichment. Here, Au NP terminated biobarcodes served as dynamic signal amplifiers that enabled a low limit-of-detection (5 fM), a wide linear range (1 fM – 100 pM), and the ability to discern between single and double base-mismatched nucleic acid sequences. In parallel, we also detail the development of an EC biosensor featuring dynamic DNA motifs, capable of reagentless, sensitive and specific detection of N-PEDv (nucleocapsid protein of porcine epidemic diarrhea virus)—a protein target with emerging global significance—in both buffer (LOD ~ 1.08 μg mL-1) and urine (LOD ~ 1.09 μg mL-1)
Ultimately, this work presents innovations in material architecture and programmable dual-signal transduction that enhance the performance metrics of biosensors; thus, presenting the potential to design POC molecular diagnostics of the future. / Thesis / Doctor of Engineering (DEng) / To address critical limitations in the field of point-of-care molecular diagnostics, it is vital to develop new tools integrating bio-recognition systems with programmable photoelectrochemical and electrochemical signal transduction that enables the design of more effective biosensors. In photoelectrochemical (PEC) systems, plasmonic materials such as gold nanoparticles are often featured to either amplify or attenuate signal response. While there is a significant amount of literature regarding the interaction of gold nanoparticles (Au NPs) with semiconductive systems, the exact nature of the interaction between the two particles has not yet been fully mapped out. In this thesis, we examine various degrees of freedom—including surface coverage density and separation distance—that influence the design of effective photoelectrochemical systems. The understanding gained is further harnessed to design dual-signal photoelectrochemical systems featuring titanium dioxide (TiO2) photoelectrodes and Au linked dynamic deoxyribonucleic acid (DNA) motifs to enable predictive modulation in response to target identification. An electrochemical (EC) analogue featuring structure switching DNA motifs and redox tagged barcodes was also developed. The resultant PEC and EC biosensing assays were critically examined, and their analytical performance was subsequently evaluated in terms of limit-of-detection, sensitivity, and specificity. Ultimately, new classes of bioassays featuring integrated biorecognition and dual-signalling capability for oligonucleotide (i.e., nucleotide sequences and aptamers) based biomolecular detection in urine and saliva were realized.
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/27495 |
| Date | January 2022 |
| Creators | Victorious, Amanda |
| Contributors | Soleymani, Leyla, Biomedical Engineering |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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