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Title: An investigation of redox self-assembled monolayer in label-free biosensor application
Author: Ho, M. Y.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2011
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This dissertation investigates a label-free sensing platform which can be used to detect DNA, enzyme or protein, based upon electrochemical detection which is suitable for implementation in microarray form. Two implementations are proposed based on mixed Ferrocene self-assembled monolayer (SAM) and the Azurin (metalloprotein) SAM. We have shown for the first time that electro-active SAM, functionalized with suitable receptors, can be employed for the detection of biomolecular interactions. Detection of streptavidin by biotin-functionalized Ferrocene SAM was successfully demonstrated. These results were made possible by the development of the fabrication protocols that optimize the SAM stability and reproducibility. Reliable samples, combined with theoretical modelling and modification of existing published model for electro-active SAM, has enabled us to experiment and analyse in depth various electrochemical detection techniques, based on changes in capacitance, voltammetric formal potential and current, Open Circuit Potential (OCP). It was found that AC voltammetry and OCP are the best measurement techniques. The use of OCP with an electro-active SAM had not been previously demonstrated and the theoretical basis for this technique was presented. Essential for this technique was the development of micro-electrodes to reduce parasitic capacitances that would reduce the available signal, enabling real-time detection of bio-molecular interaction. We also made possible to characterize the binding of a protein (streptavidin) to a biotin-functionalized Azurin SAM. Also a numerical analysis has been developed to analyse the effect of design parameters of the platform, such as the probe density and buffer concentration, which can greatly affect the assay sensitivity. This is achieved using 3D simulation with finite element method in COMSOL.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available