Optical signaling strategies for use in a multi-component sensor array
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This dissertation consists of four chapters that focus on various methods and signaling strategies by which different analytes in solution can be detected within a multi-component sensor array. The first chapter of this dissertation is a review of recent work in the area of chemical sensing. A discussion is provided here of the concepts and basic mechanisms required for a sensing event and different approaches to designing molecular receptors. Next, chemical sensing is described through examples of detection strategies documented in the literature. The introductory chapter concludes by relating different sensory mimics to current methods for vapor and solution phase analyte detection using multicomponent sensor arrays and discussing the importance of pattern recognition protocols for the successful application of sensor arrays. Chapter 2 discusses competitive indicator-displacement methods for the solution-based UV-Visible analysis of citrate and calcium in beverages. A host compound containing three guanidinium moieties on a triethylbenzene core is employed to bind citrate. Improvements to the sensing scheme via complexometric dyes known to bind calcium ion and the host are described. Application of artificial neural networks to the spectral data also allowed for the evaluation of citrate and calcium concentrations in flavored vodkas. Chapter 3 describes a new sensing protocol by coupling a combinatorial library of resin-bound receptors to a multi-component sensor array. The anchored receptor includes a rationally designed scaffold with peptide libraries and is used to bind various nucleotide phosphates. Analyte detection is accomplished by a competition assay using fluorescein as the signaling compound. Principal component analysis shows that the sensing ensembles create a fingerprint response for each compound analyzed in the sensor array. Chapter 4 applies the combinatorial array sensor system described in the previous chapter toward the detection of nerve agent hydrolysis products. First, the synthesis of a control resin-bound peptide library is presented to elucidate the role of the scaffold plays in binding analytes. Studies that lend to an understanding of the sensing protocol mechanism are discussed next in the context of redesigning and optimizing assay conditions. The importance of data processing on the outcome of the principal component analysis is also described. Finally, ideas for expanding the utility of this sensing protocol toward the detection of other classes of analytes via the combinatorial approach are proposed.