有機染料之螢光感測分子於活性氧物質及金屬離子之偵測與生物影像之應用

Abstract

Abstract Organic compounds have been used extensively to construct photo luminescent materials, solar cells and chemosensors. Its significance can be attributed to easy synthesis, inexpensive staring materials, easy to tune photo physical properties and easy to link with other supporting materials. Fluorescence sensing is a process in which interaction between species is detected by change in the fluorescence intensity of system. Organic dyes are ideally suited to be used as probes for fluorescence sensing. This work therefore is focused on synthesis of organic fluorophores and their applications in bioimaging. Chapter 1 describes importance of chemosensors, mechanism of signal transduction, and parameters needed to optimize in every sensor. How organic dyes been used as fluorescent sensors is further explained in following chapters. Chapter 2 describes the synthesis of BODIPY based fluorescent probes (HCS and HCS2) for hypochlorite sensing. Both probes exhibited highly sensitive to hypochlorite over other reactive oxygen species and reactive nitrogen species. HCS and HCS2 are virtually non-fluorescent as photo-induced electron transfer taking place from sulfur to BODIPY. Hypochlorite induced oxidation of sulfur to sulfoxide which inhibited the PET process and generates turn-on fluorescence in a molecule. This mechanism was further supported by DFT calculations (B3LYP/6-31G (d)). Both probes are shown their ability to map external addition and internal secretion of hypochlorite in RAW 264.7 cells. Chapter 3 reports design, synthesis and characterization of hydrogen peroxide sensing probes HP1 and HP2. Both probes exhibited highly sensitive to hydrogen peroxide over other reactive oxygen species and reactive nitrogen species. Hydrogen peroxide triggers cleavage of boronic ester and followed by intramolecular nucleophilic attack of the phenolic oxygen to the nitrile group resulting cyclized iminocoumarin-benzothiazoles and iminocoumarin, respectively. HP1 and HP2 are shown their ability to map intercellular accumulation of hydrogen peroxide in HeLa cells. iii Chapter 4 reports engineering boron-dipyrromethene (BODIPY) scaffold for chemosensing. A new boron–dipyrromethene (BODIPY) derivative (FS1) containing two triazole units exhibits an enhanced fluorescence in the presence of Hg2+ ions and a high selectivity for Hg2+ ions over competing metal ions in methanol: Ag+, Ca2+, Cd2+, Co2+, Cu2+, Fe2+, Fe3+, K+, Mg2+, Mn2+, Ni2+, Pb2+, and Zn2+ produced only minor changes in the fluorescence of FS1. The apparent dissociation constant (Kd) of FS1–Hg2+ was found to be 62 μM. Moreover, fluorescence microscopy experiments showed that FS1 can be used as a fluorescent probe for detecting Hg2+ ions in living cells. Chapter 5 discusses a new monostyryl boron dipyrromethene derivative (MS1) which is appended with two triazole units and indicates the presence of Hg2+ among other metal ions with high selectivity by color change and red emission. Upon Hg2+ binding, the absorption band of MS1 is blue-shifted by 29 nm due to the inhibition of the intramolecular charge transfer from the nitrogen to the BODIPY, resulting in a color change from blue to purple. Significant fluorescence enhancement is observed with MS1 in the presence of Hg2+; the metal ions Ag+, Ca2+, Cd2+, Co2+, Cu2+, Fe2+, Fe3+, K+, Mg2+, Mn2+, Ni2+, Pb2+, and Zn2+ cause only minor changes in the fluorescence of the system. The apparent association constant (Ka) of Hg2+ binding in MS1 is found to be 1.864 × 105 M−1. In addition, fluorescence microscopy experiments show that MS1 can be used as a fluorescent probe for detecting Hg2+ in living cells. Chapter 6 describes colorimetric detection of Hg2+ ion by an NBD dye. Upon Hg2+ recognition, the absorption band of CS1 is red-shifted by 39 nm and caused color change from orange to red. The absorption of CS1 is red sifted only in the presence of Hg2+; the metal ions Ag+, Ca2+, Cd2+, Co2+, Cu2+, Fe2+, V2+, Mg2+, Mn2+, Ni2+, and Zn2+ cause only minor changes in the absorbance spectra. The apparent association constant (Ka) of Hg2+-CS1 is found to be 1.71 × 104 M−1. In addition, NMR spectrometric titrations were also carried out to demonstrate Hg2+ binding event with CS1.

Abstract Organic compounds have been used extensively to construct photo luminescent materials, solar cells and chemosensors. Its significance can be attributed to easy synthesis, inexpensive staring materials, easy to tune photo physical properties and easy to link with other supporting materials. Fluorescence sensing is a process in which interaction between species is detected by change in the fluorescence intensity of system. Organic dyes are ideally suited to be used as probes for fluorescence sensing. This work therefore is focused on synthesis of organic fluorophores and their applications in bioimaging. Chapter 1 describes importance of chemosensors, mechanism of signal transduction, and parameters needed to optimize in every sensor. How organic dyes been used as fluorescent sensors is further explained in following chapters. Chapter 2 describes the synthesis of BODIPY based fluorescent probes (HCS and HCS2) for hypochlorite sensing. Both probes exhibited highly sensitive to hypochlorite over other reactive oxygen species and reactive nitrogen species. HCS and HCS2 are virtually non-fluorescent as photo-induced electron transfer taking place from sulfur to BODIPY. Hypochlorite induced oxidation of sulfur to sulfoxide which inhibited the PET process and generates turn-on fluorescence in a molecule. This mechanism was further supported by DFT calculations (B3LYP/6-31G (d)). Both probes are shown their ability to map external addition and internal secretion of hypochlorite in RAW 264.7 cells. Chapter 3 reports design, synthesis and characterization of hydrogen peroxide sensing probes HP1 and HP2. Both probes exhibited highly sensitive to hydrogen peroxide over other reactive oxygen species and reactive nitrogen species. Hydrogen peroxide triggers cleavage of boronic ester and followed by intramolecular nucleophilic attack of the phenolic oxygen to the nitrile group resulting cyclized iminocoumarin-benzothiazoles and iminocoumarin, respectively. HP1 and HP2 are shown their ability to map intercellular accumulation of hydrogen peroxide in HeLa cells. iii Chapter 4 reports engineering boron-dipyrromethene (BODIPY) scaffold for chemosensing. A new boron–dipyrromethene (BODIPY) derivative (FS1) containing two triazole units exhibits an enhanced fluorescence in the presence of Hg2+ ions and a high selectivity for Hg2+ ions over competing metal ions in methanol: Ag+, Ca2+, Cd2+, Co2+, Cu2+, Fe2+, Fe3+, K+, Mg2+, Mn2+, Ni2+, Pb2+, and Zn2+ produced only minor changes in the fluorescence of FS1. The apparent dissociation constant (Kd) of FS1–Hg2+ was found to be 62 μM. Moreover, fluorescence microscopy experiments showed that FS1 can be used as a fluorescent probe for detecting Hg2+ ions in living cells. Chapter 5 discusses a new monostyryl boron dipyrromethene derivative (MS1) which is appended with two triazole units and indicates the presence of Hg2+ among other metal ions with high selectivity by color change and red emission. Upon Hg2+ binding, the absorption band of MS1 is blue-shifted by 29 nm due to the inhibition of the intramolecular charge transfer from the nitrogen to the BODIPY, resulting in a color change from blue to purple. Significant fluorescence enhancement is observed with MS1 in the presence of Hg2+; the metal ions Ag+, Ca2+, Cd2+, Co2+, Cu2+, Fe2+, Fe3+, K+, Mg2+, Mn2+, Ni2+, Pb2+, and Zn2+ cause only minor changes in the fluorescence of the system. The apparent association constant (Ka) of Hg2+ binding in MS1 is found to be 1.864 × 105 M−1. In addition, fluorescence microscopy experiments show that MS1 can be used as a fluorescent probe for detecting Hg2+ in living cells. Chapter 6 describes colorimetric detection of Hg2+ ion by an NBD dye. Upon Hg2+ recognition, the absorption band of CS1 is red-shifted by 39 nm and caused color change from orange to red. The absorption of CS1 is red sifted only in the presence of Hg2+; the metal ions Ag+, Ca2+, Cd2+, Co2+, Cu2+, Fe2+, V2+, Mg2+, Mn2+, Ni2+, and Zn2+ cause only minor changes in the absorbance spectra. The apparent association constant (Ka) of Hg2+-CS1 is found to be 1.71 × 104 M−1. In addition, NMR spectrometric titrations were also carried out to demonstrate Hg2+ binding event with CS1.