Aptamers are known to undergo adaptive conformational change upon ligand binding, causing micro-environment rearrangements that may be linked with stilbene transducers.Stilbene displays fluorescence decay upon on continuous excitation, which is sensitive to micro-environment sterics. This thesis hypothesizes that fluorescence decay based biosensing can be achieved by incorporating the molecular recognition properties of aptamer with time-dependent stilbene trans-cis photodecay. Two designs were proposed and tested according to the hypothesis: 1) "competitive binding of stilbene-analyte conjugate with analyte" and 2) "stilbene-aptamer conjugate fluorescence decay correlates to analyte binding". Malachite green aptamer (MGA) and its ligand malachite green (MG)were chosen as a model study to test the hypothesis. Prior to hypothesis investigation, experimental conditions were established and optimized. The MGA/MG binding was found to have hydrolysis-dependent photodecay, but organic additives were found to reverse the hydrolysis and ultimately stabilize the binding. For the design 1), MG-stilbene conjugates obtained for the hypothesis testing had micromolar binding affinities with appreciable photodecay. Based on the MG-stilbene conjugates analyzed, electron Uncomplexed stilbeneThe thesis consists of the following seven chapters:Chapter 1 briefly describes the research background of the study, followed by an introduction of research motivation, hypothesis and scopes, and finally outlines the overview and outcomes of the thesis.Chapter 2 reviews the historical and state-of-the-art background of biosensors, aptamers and stilbenes, with research gaps highlighted. The advantages of aptamers and stilbenes are reviewed within a biosensor perspective. A model system, comprising of malachite green aptamer, is proposed to challenge the hypothesis above.Chapter 3 introduces the main experimental methods or techniques and their corresponding principles, including K d determination, bioconjugation, and fluorescence decay analysis.Chapter 4 refines the conditions for MGA/MG binding. pH and organic additives 2. MG-stilbene conjugates were synthesized and their binding affinities to MGA and fluorescence properties were measured for the first time, providing structure activity relationships required in ligand-stilbene aptameric biosensors.
3.MGA-stilbene conjugate was synthesized successfully, with a linear correlation of