Thesis
Biosensor design based on immunobinding-induced fluorescence polarization change and quantum dots fluorescence quenching by gold nano-particles via bioconjugation
Washington State University
Master of Science (MS), Washington State University
2009
Handle:
https://hdl.handle.net/2376/102283
Abstract
Biosensors can recognize analytes, which are biomolecules or combined with biomolecules, by converting physiological data into detectable signals. Cardiac troponin I (cTnI) and cardiac troponin T (cTnT) have been drawing researchers' attention as markers for myocardial infarction due to their superior specificity and sensitivity for acute myocardial infarction. This thesis reports a novel dual-sensing scheme which is based on immunobinding-induced fluorescence polarization change in detection of these two cardiac markers. It also describes the efforts made in exploring the feasibility of using Förster resonance energy transfer (FRET) between gold nano-particles and quantum dots in biomarker sensing. In the first design format, two small peptides corresponding to cTnI and cTnT were synthesized and labeled with different fluorescent dyes. After forming complexes with their antibodies, competition assays were performed in order to obtain standard curves which could be applied in real sample analysis. Measurements were taken with increasing complexity from simple single peptide condition to mixed peptide in human plasma condition. The successful measurements at all conditions for both peptides demonstrate the good sensitivity, specificity, robustness, and promising potential applications in clinical diagnosis. Luminescent quantum dots have distinctive properties over conventional organic fluorophores for their high quantum yield, size-tunable emission, broad absorption and narrow emission spectra, whereas gold nano-particles can induce strong fluorescence quenching of a fluorophore which is in a proximate distance. Using them as a FRET donor and acceptor pair in conjunction with the immunological interactions of biomolecules labeled on their surface, this system has shown effective sensing capability, and more than 50% of fluorescence was observed to be quenched at optimum testing conditions. Size of gold nano-particles, biotin to gold ratio, and biotinylated gold nanoparticle to streptavidin conjugated quantum dot ratio were found to play important roles in regulating the system's quenching efficiency.
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Details
- Title
- Biosensor design based on immunobinding-induced fluorescence polarization change and quantum dots fluorescence quenching by gold nano-particles via bioconjugation
- Creators
- Yanling Qiao
- Contributors
- Wen-ji Dong (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Chemical Engineering and Bioengineering, School of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; [Pullman, Washington] :
- Identifiers
- 99900525051601842
- Language
- English
- Resource Type
- Thesis