Doctor of Philosophy (PhD)
Anions play important roles in biological systems. The design of anion sensors has been of great interest. The selective detection of a specific anion is particularly challenging. In the first chapter, I describe the synthesis of a TBS-protected fluorescein dye (1.1) and its use for the selective detection of fluoride. Solutions of 1.1 either in DCM or in aqueous media at physiological pH show the excellent selectivity towards fluoride to afford color formation while solutions of other interfering anions remain colorless. The monitoring of homocysteine (Hcy) and cysteine (Cys) levels is important since they are biomarkers associated with Alzheimer’s and cardiovascular disease, among many others. In the second chapter, the selective detection of Hcy and Cys over other amino acids using a library of chromogenic reagents and their application in an HPLC post-column system are described. Saccharides are widely used in industrial processes and biological systems. The determination of a specific saccharide is difficult since sugars are colorless and structurally similar to each other. Futhermore, the colorimetric detection of oligosaccharides via conventional methods is difficult. In the third chapter, I have reported the synthesis of a boronic acid-appended rhodamine dye (3.1) and its application towards the detection of mono- and oligosaccharides via an HPLC post-column system. The selectivity of 3.1 towards fructose allows one to detect fructose in the presence of a 100-fold excess of glucose. The detection of sialic acid is also described. In the fourth chapter, the elucidation of the mechanism of the origin of color formation in resorcinarene macrocyclic compounds is explained in detail. The in situ acid formation from DMSO decomposition can cause the ring-opening of resorcinarenes followed by the condensation of resultant products to afford xanthene dyes. This discovery has influenced the development of other indicator molecules discussed in the previous chapters. In the last chapter, I reported the synthesis of a cysteine-conjugated rhodamine dye and its application in the selective detection of α-dicarbonyl compounds and a DNA lesion marker. These ongoing research projects will continue. New studies including optimizing sensing conditions and the elucidation of selective binding mechanism include future work.
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Kim, Kyukwang, "Detection of Biologically Important Molecules" (2005). LSU Doctoral Dissertations. 931.