Hydrazone Derivatives As Fluorescent Probes For Metal Ions And Fluorescence Detection Of Single-nucleotide Polymorphisms

A series of hydrazone derivatives were synthesized and their potential application as fluorescent probes for Cu²⁺, Zn²⁺ and Mg²⁺ was investigated in this dissertation. The interaction between these fluorescent probes and metal ions could be divided into two different mechanisms, i.e., metal ion-induced reaction and metal ion-ligand chelation. In the former case, 7-diethylamino-3-[(2-hydroxy-phenylimino) -methyl]-coumarin was designed and synthesized as a fluorescence"turn-on"probe for Cu²⁺ via Cu²⁺-promoted hydrolysis of the lactone moiety in coumarin. The probe showed high sensitivity to Cu²⁺ in water solution with a detection limit of 20 nM. Fluorescence response of the probe to Cu²⁺ was also highly selective, because other metal ions could neither promote nor interfere the hydrolysis reaction. In the latter case, novel fluorescence probes salicylaldehyde 4-pyren-1-yl-butyric hydrazone and 4-N,N-diethylamino-salicylaldehyde rhodamine B hydrazone for Zn²⁺ were developed. They exhibited selective and ratiometric fluorescent response toward Zn²⁺ over other metal ions in aqueous ethanol. Salicylaldehyde 4-pyren-1-yl-butyric hydrazone exhibited a linear range of 0⁵.0μM and detection limit of 80 nM for Zn²⁺ in optimal condition. 4-N,N-diethylamino-salicylaldehyde rhodamine B hydrazone exhibited a linear range of 0¹0.0μM and the detection limit was found to be 50 nM for Zn²⁺. When 4-N,N-diethylamino-salicylaldehyde rhodamine B hydrazone was used, fluorescence emission color changed from dark cyan to green yellow by formation of a 1:1 metal-to-ligand complex and the color change could be easily recognized by naked eye. Detection of Zn²⁺ in real water samples using the two probes was successfully carried out. In addition,α-(quinlin-8-yloxy)-acetyl salicyl hydrazone was proposed as a fluorescent probe for Mg²⁺. Significant absorption spectra changes and fluorescence enhancement were observed upon chelation of the probe with Mg²⁺.In this dissertation, a double-probe method and a bulge form method were also proposed for the detection of single-nucleotide polymorphisms (SNPs) by coupling with a small fluorescent dye 2-amino-5, 7-dimethyl-1, 8-naphthyridine (ADMND). Since the methods required no labeling of DNA strands and thus simple, economic and cost-effective SNPs detection was realized. Using the double-probe method and bulge form method, ADMND was successfully applied to the detection of C/G and C/A mutations in the estrogen receptor 2 gene and the progesterone receptor genes.