Development of optical and electrochemical methods at the nano-scale for high-throughput biochemical sensing

Siu, Vince Shing-Wing

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Year:: 2014
Contributor:: Siu, Vince Shing-Wing (creator); Palmore, Tayhas (Director); Pacifici, Domenico (Director); Tripathi, Anubhav (Reader); Wessel, Gary (Reader); MacDonald, John (Reader); Brown University. Biomedical Engineering (sponsor)
Genre:: theses
Subject:: Intein; Plasmonic Interferometry; Biosensors; Electrochemistry; Vitamin D; Glucose
Extent:: 37, 191 p.
DOI: https://doi.org/10.7301/Z0BR8QH6

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Abstract:: Over the past few decades, remarkable progress has been made in the development of analytical biosensors for use in medical diagnostics. This dissertation focuses on the development of four biosensors that utilize electrochemical and optical transducers to detect vitamin D and glucose, all of which may be modified to detect other biochemical analytes. Nano-structured materials (e.g. DNA, proteins and nano-grooves/slits) were used together with molecular biology and surface chemistry to create signal transducers that can be miniaturized and integrated with microfluidic devices to yield novel biosensing platforms that could result in faster diagnostics of disease and the consequential improvement in health care. Briefly, the first sensor studied the electrochemical properties of CYP27B1 immobilized in a surfactant film on an edge-plane graphite electrode. Cyclic voltammetry revealed a mid-point potential of –180 +/- 5 mV (vs. Ag/AgCl) and the rate of heterogeneous electron transfer was 3.5 +/- 0.6 s-1. The lipid film was found to perturb the structural integrity of CYP27B1 and thus, the catalytic conversion of 25(OH)D3 to 1α,25(OH)2D3 was not observed. The second sensor detects the electrochemical impedance change upon the binding of 1α,25(OH)2D3 to a vitamin D receptor embedded in a lipid film on a gold electrode. The response time of the modified electrodes is <10 min with a detection limit of 52 nM. The third sensor consists of a DNA biocircuit that encodes for a bacterial sensor protein that can be expressed and triggered to produce a dose-dependent fluorescent response in the presence of 1α,25(OH)2D3. Different parameters including receptor length, induction conditions, and the addition of pelB sequence were investigated to optimize the expression of an active sensor protein into the soluble fraction. The final sensor studied is a groove-slit-groove plasmonic interferometer designed, fabricated and characterized for real-time monitoring of glucose. The detection limit for glucose in aqueous solutions is 5.5 µM with a sensitivity of 105,000 %/RIU. To address the issue of selectivity, the plasmonic interferometer was coupled to a dye assay, which enabled specific detection of glucose in a complex mixture of salts and small molecules (i.e., artificial saliva) and an 8.5-fold increase in sensitivity.
Notes:: Thesis (Ph.D. -- Brown University (2014)

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Siu, Vince Shing-Wing, "Development of optical and electrochemical methods at the nano-scale for high-throughput biochemical sensing" (2014). Biomedical Engineering Theses and Dissertations. Brown Digital Repository. Brown University Library. https://doi.org/10.7301/Z0BR8QH6

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Biomedical Engineering Theses and Dissertations

Theses and Dissertations for the Biomedical Engineering department.
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