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Book Design and Synthesis of Photo induced Electron Transfer Based Fluorescent Probes for Pyruvate and Zinc Detection

Download or read book Design and Synthesis of Photo induced Electron Transfer Based Fluorescent Probes for Pyruvate and Zinc Detection written by Charles D. Cook and published by . This book was released on 2007 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt: The design and synthesis of fluorescent chemosensor probes based on photoinduced electron transfer is discussed. First, the design of a series of probes to detect the presence of divalent metal cations is discussed. Next, the results for an existing probe for divalent cations are examined. Computational chemistry is used to provide a possible answer to its selectivity. This method of examination suggests that the probes selectivity is due to the bonding involved in analyte coordination. Then, the design of a series of probes to detect the presence of mono-, di-, and, trivalent hydrocarbon anions is discussed. From this discussion, the synthesis of a single probe from that series as well as characterization and the spectrophotometric results from its titration with pyruvate, malate, and citrate is discussed, respectively. The probe was found to be more selective and sensitive toward pyruvate. Work is currently underway to design and synthesize other series of probes to detect this family of anion.

Book Design and Synthesis of Fluorescent Sensors for Zinc Based on Photoinduced Electron Transfer PET

Download or read book Design and Synthesis of Fluorescent Sensors for Zinc Based on Photoinduced Electron Transfer PET written by Surendra K. Puli and published by . This book was released on 2006 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt: Chemistry has become an important tool in solving problems in biology and medicine. Chemists are engaged in developing new devices at the nanoscale level to aid in clinical diagnosis, real time monitoring of analytes, and analyzing neural activity, etc. Our research is aimed at designing and synthesizing fluorescent sensors to detect various divalent metal ions under physiological conditions. We designed and synthesized a chemosensor based on the principle of photoinduced electron transfer as a signal transduction mechanism in order to detect the presence of various divalent metal cations, particularly zinc. We report the synthesis, characterization and its spectrophotometric titrations with various metal ions. This sensor signals the presence of metal ions by a fluorescence signal and offers a significant advantage as it exhibits "off-on" behavior in the presence and absence of metal ions. The primary sensor was found to be very sensitive and selective toward zinc ions. We also aimed at optimizing the performance of this chemosensor by taking advantage of electron donating/withdrawing abilities of different functional groups by using computational methods. We devised a new scheme to synthesize it, unfortunately the modified sensor was not realized for unknown reason. We are currently involved in devising an alternate strategy to synthesize and develop new sensors for neutral molecules.

Book Studies on Fluorescent Probes for the Specific Detection of Reactive Oxygen Species and Reactive Nitrogen Species in Living Cells

Download or read book Studies on Fluorescent Probes for the Specific Detection of Reactive Oxygen Species and Reactive Nitrogen Species in Living Cells written by Zhenning Sun and published by . This book was released on 2017-01-27 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation, "Studies on Fluorescent Probes for the Specific Detection of Reactive Oxygen Species and Reactive Nitrogen Species in Living Cells" by Zhenning, Sun, 孫振宁, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of thesis entitled STUDIES ON FLUORESCENT PROBES FOR THE SPECIFIC DETECTION OF REACTIVE OXYGEN SPECIES AND REACTIVE NITROGEN SPECIES IN LIVING CELLS Submitted by SUN Zhen-Ning for the Degree of Doctor of Philosophy at The University of Hong Kong in September 2006 This project mainly focuses on the development of fluorescent probes for two biologically important oxidants - peroxynitrite and hypochlorite. On the basis of the similar chemical behavior between peroxynitrite - - (ONOO ) and peroxymonosulfate (HOOSO ), a reaction specific to peroxynitrite has been discovered (Scheme 1). On the basis of this specific reaction, several BODIPY-type fluorescent probes have been designed and synthesized according to the photoinduced electron transfer (PET) mechanism (Scheme 2). Among those probes, SZN-2 was found to be highly sensitive in specific detection of peroxynitrite 1 -- without interference from other competing oxidants, such as H O, O, NO, O, 2 2 2 2 and alkylperoxyl radical (ROO). Upon treatment with 7 equiv of peroxynitrite, probe SZN-2 showed up to 69-fold increase in fluorescence intensity. A linear correlation between emission intensity and concentration of peroxynitrite was observed. Moreover, the formation of peroxynitrite in living cells (J744.1 macrophages) can be visualized selectively by using probe SZN-2. This novel fluorescent probe should significantly facilitate studies of the biological roles of peroxynitrite in oxidative stress and many peroxynitrite-associated human diseases, such as rheumatoid arthritis, heart disease, atherosclerosis, and stroke. A fluorescent probe, SZN-3, has also been developed for the detection of hypochlorite on the basis of a specific reaction between methoxyphenol and hypochlorite (Scheme 3). This probe is highly sensitive and specific to hypochlorite. Upon treatment with 5 equiv of hypochlorite, probe SZN-3 showed up to 754-fold increase in fluorescence intensity. The reactivities of SZN-3 toward different reactive oxygen species (ROS) and reactive nitrogen species (RNS), including H O, 2 2 1 -- - - - - O, NO, O, OH, OCl, ONOO and alkylperoxyl radical (ROO ) were compared. 2 2 The results showed that fluorescence increased only upon reaction with OCl, demonstrating that probe SZN-3 has much higher selectivity towards hypochlorite than other ROS and RNS in an abiotic system. Moreover, using probe SZN-3, the formation of OCl has been successfully detected in an enzymatic system - (Myeloperoxidase/H O /Cl system) and in macrophages upon stimulation. This 2 2 new probe has provided an efficient tool for the evaluation of the roles of OCl in biological systems. Scheme 1 ONOO O OH CF CF RO 2.2 R = Me 2.1a R = H 3.23 Oxidant CF 3 No Reaction H O, OH, NO 2 2 RO 1 . O O 2, 2 R = Me 2.1a R = H 3.23 Scheme 2 O O CF CF 3 3 RO MeO NN NN B B Et NOC CONEt Et NOC CONEt F F F F 2 2 2 2 3.8 R = Me 2.14 (SZN-1) R = MOM 3.22 3.29 (SZN-2) R = H OH CF CF HO ONOO NN NN Et NOC CONEt Et NOC CONEt 2 2 F F 2 2 F F 3.29 (SZN-2) 2.15 non-fluorescent fluorescent Scheme 3 O O OMe OCl O O OH 4.1 4.2 OMe Oxidant No Reaction H O, OH, NO 2 2 1 . O O 2, 2 OH OMe

Book Fluorescent Energy Transfer Nucleic Acid Probes

Download or read book Fluorescent Energy Transfer Nucleic Acid Probes written by Vladimir V. Didenko and published by Springer Science & Business Media. This book was released on 2008-02-04 with total page 368 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fluorescent nucleic acid probes, which use energy transfer, include such constructs as molecular beacons, molecular break lights, Scorpion primers, TaqMan probes, and others. These probes signal detection of their targets by changing either the intensity or the color of their fluorescence. Not surpr- ingly, these luminous, multicolored probes carry more flashy names than their counterparts in the other fields of molecular biology. In recent years, fluor- cent probes and assays, which make use of energy transfer, have multiplied at a high rate and have found numerous applications. However, in spite of this explosive growth in the field, there are no manuals summarizing different p- tocols and fluorescent probe designs. In view of this, the main objective of Fluorescent Energy Transfer Nucleic Acid Probes: Designs and Protocols is to provide such a collection. Oligonucleotides with one or several chromophore tags can form fluor- cent probes capable of energy transfer. Energy transport within the probe can occur via the resonance energy transfer mechanism, also called Förster tra- fer, or by non-Förster transfer mechanisms. Although the probes using Förster transfer were developed and used first, the later non-Förster-based probes, such as molecular beacons, now represent an attractive and widely used option. The term “fluorescent energy transfer probes” in the title of this book covers both Förster-based fluorescence resonance energy transfer (FRET) probes and probes using non-FRET mechanisms. Energy transfer probes serve as molecule-size sensors, changing their fluorescence upon detection of various DNA reactions.

Book Pyrazoline Based Fluorescent Probes and Liposomes What Is It All About

Download or read book Pyrazoline Based Fluorescent Probes and Liposomes What Is It All About written by Jonathan Hofmekler and published by LAP Lambert Academic Publishing. This book was released on 2012 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt: 1,3,5-triarylpyrazoline based fluorescent probes which act as "turn-on" probes, have been extensively researched and are now widely used in biological research. These probes achieve their fluorescence "turn-on" response by inhibition of fluorescence quenching by acceptor-excited photoinduced electron transfer upon binding of an analyte. It has been recently shown that some fluorescent probes form colloids composed of nanoparticles, due to their hydrophobic character. This hydrophobic character can also lead to partitioning of the probe into cellular membranes. Colloid formation and membrane partitioning may affect the probes' photophysical properties. The photoinduced electron transfer process is greatly affected by the polarity of the medium in which the probe is used. In this study, the effect of membrane proximity on the photoinduced electron transfer process for pyrazoline based probes has been investigated. A series of water soluble 1,3,5-triarylpyrazolines have been synthesized in which a N, N-dialkylaniline moiety acts as an electron donor and a proton acceptor and an alkylated sulfonamide moiety acts as a molecular anchor for interaction with neutral and anionic liposomes.

Book Investigating the Effect of Membrane Anchoring on Photoinduced Electron Transfer Pyrazoline Based Fluorescent Probes

Download or read book Investigating the Effect of Membrane Anchoring on Photoinduced Electron Transfer Pyrazoline Based Fluorescent Probes written by Jonathan Hofmekler and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Fluorescence microscopy is a powerful analytical tool for visualizing biological processes at the subcellular level. In this regard, 1,3,5-triarylpyrazoline based fluorescent probes which act as "turn-on" probes, have been extensively researched. These probes achieve their fluorescence "turn-on" response by inhibition of fluorescence quenching by acceptor-excited photoinduced electron transfer upon binding of an analyte. It has been recently shown that some fluorescent probes used in biological research form colloids composed of nanoparticles, due to their hydrophobic character. This hydrophobic character can also lead to partitioning of the probe into cellular membranes. Colloid formation and membrane partitioning may affect the probes' photophysical properties such as absorption and emission wavelength and quantum yields. Recently, a series of 1,3,5-triarylpyrazolines synthesized in our group by M.T. Morgan, showed no formation of aggregates in aqueous buffer. Surprisingly, these probes increased their fluorescence intensity in the presence of liposomes. The photoinduced electron transfer process is greatly affected by the polarity of the medium in which the probe is used. In this study, the effect of membrane proximity on the photoinduced electron transfer process for pyrazoline based "turn-on" probes has been investigated. A series of water soluble 1,3,5-triarylpyrazolines have been synthesized in which a N, N-dialkylaniline moiety acts as an electron donor and a proton acceptor and an alkylated sulfonamide moiety acts as a molecular anchor for interaction with neutral and anionic liposomes.

Book Rational Design Synthesis and Characterization of Response Selective Fluorescent Sensors

Download or read book Rational Design Synthesis and Characterization of Response Selective Fluorescent Sensors written by Ruisong Xu and published by . This book was released on 2007 with total page 185 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this dissertation, we established a new approach assisted by computational chemistry to design fluorescent sensors. The approach is applicable to predict the behavior of a fluorophore-bridge-receptor sensor based on photoinduced electron transfer (PET). Our first designed rhodamine based pH sensor exhibits strong fluorescence under acidic conditions and very weak fluorescence under basic conditions, just as the computations predicted.

Book DESIGN AND DEVELOPMENT OF NEAR INFRARED FLUORESCENT PROBES FOR SENSING PH HYPOXIA AND PEROXYNITRITE

Download or read book DESIGN AND DEVELOPMENT OF NEAR INFRARED FLUORESCENT PROBES FOR SENSING PH HYPOXIA AND PEROXYNITRITE written by and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract : pH and hypoxia levels are two important diagnostic biomarkers in biological systems and abnormal levels will cause many diseases. The metabolism and transportation of peroxynitrite in biological systems involve a series of important enzymes and proteins. Peroxynitrite generation represents a crucial pathogenic mechanism in conditions such as stroke, myocardial infarction, chronic heart failure, diabetes, circulatory shock, chronic inflammatory diseases, cancer, and neurodegenerative disorders. As a result, it is very important to detect and evaluate the levels of pH, hypoxia, and peroxynitrite in vivo to study the functionality of enzymes and provide practical applications for cancer diagnosis and therapy. Fluorescence detection and imaging offer a sensitive non-invasive method because it provides clear images of cellular three-dimensional structures, and can illustrate cellular multiple overlapping structures simultaneously, and enable image-guided surgery. However, it is challenging to design fluorescent probes with good fluorescence signals, low background noise, and multifunctional detection capability. In order to overcome these drawbacks, we have designed and synthesized a series of excellent fluorescent probes to detect pH, hypoxia, and peroxynitrite with good fluorescence signals, fast responses, low background noise, and multifunctional detection capabilities. The probes combine advantages of near-infrared imaging such as low fluorescence background interference, less photodamage to cells and tissues, and deep-tissue penetration with ratiometric imaging, this latter aspect reduces systematic errors with solely intensity-based fluorescent probes caused by fluctuations in the excitation light source, variations in probe concentrations, and different probe compartmental localizations. We have developed a new backbone for making near-infrared fluorescent probes. This new backbone has a reactive chlorine group for modifying the detectors. Based on this new backbone, we introduced a pH-responsive detector to prepare three pH-sensitive near-infrared fluorescent probes with high fluorescence quantum yields. We designed and synthesized a series of fluorescent probes on detecting hypoxia level. The nitro group was introduced directly in the conjugation system of the fluorophore, which make it fast response and ultra-sensitive. Additionally, by changing the electron-withdrawing abilities of the substitution group on 9-position of acridine moiety, the fluorescent probes show a significant different detection limit and sensitivity towards nitroreducatse. For third project, we developed a fluorescent probe responding to peroxynitrite. The probe contains a near-infrared fluorophore and a coumarin moiety and connected through a conjugated triple bond linker. The ester group of the coumarin moiety in the conjugation system can enhance the sensitivity of the ONOO- detection. For the fourth project, we developed multi-response fluorescent probe. This probe can detect pH and ONOO- with different fluorescent changes. Base pH condition can induce an on-off fluorescent change on the probe, and the ONOO- can generate a ratiometric fluorescent change.

Book Synthesis and Characterization of Novel Fluorescent Sensors Based on Terpyridine Benzoxazole and Benzothiazole Chromophores

Download or read book Synthesis and Characterization of Novel Fluorescent Sensors Based on Terpyridine Benzoxazole and Benzothiazole Chromophores written by Xiaoman Bi and published by . This book was released on 2017 with total page 173 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the past few decades, there has been significant interest in developing fluorescent probes, because they are useful tools for biological studies. As effective analytical techniques, fluorescent probes utilize distinct advantages offered by fluorescence detection in terms of sensitivity, selectivity, and fast response time. When fluorescent probes interact selectively with target molecules, ions or biological specimens, they can generate large optical responses. Since most ions or molecules, such as Zn2+, Ca2+, or pyrophosphate ion (PPi), are non-fluorescent, chemosensors having analyte binding-triggered fluorescence are appealing in many fields, like analytical chemistry, clinical biochemistry, medicine, and environmental science.This dissertation is devoted to the design, synthesis, and characterization of novel fluorescent sensors for Zn2+ and its associated applications. Chapter II of this dissertation presents several novel terpyridine-based fluorescent sensors with different substituents affecting the electronic and steric nature of the terpyridine (tpy) fluorophore. Sensors are designed to establish the correlation between sensor structure and its photophysical properties. Low temperature fluorescence is used to evaluate the essential role of intramolecular charge transfer (ICT) in zinc binding-induced fluorescence changes. The tpy molecular fragment has a relatively large [pi]-conjugated system which enables the potential [pi-pi] interaction between two tpy platforms and affects the fluorescence of tpy ligands. Chapter III introduces a dimeric tpy ligand containing two tpy fragments connected via a meta-phenylene unit. The detailed spectroscopic study shows that this ligand displays an attractive fluorescence turn-on, in sharp contrast to mono(tpy) ligand that shows fluorescence quenching upon binding Zn2+. The result suggests the existence of delicate structural influences on fluorescence of tpy derivatives.Chapter IV is devoted to 2-(2'-hydroxyphenyl)-1,3-benzoxazole (HBO) and 2-(2'-hydroxyphenyl)-1,3-benzothiazole (HBT) derivatives featured with a structural potential of excited-state intramolecular proton transfer (ESIPT). The study reveals additional information on the binding of HBO or HBT to metal cations, which aids the sensor design for Zn2+ and PPi detection. The molecular design aims to realize ESIPT process control upon complexation with an analyte. Chapter V is devoted to the synthesis of bis(HBO) derivatives which bind Zn2+ selectively and emit near-infrared (NIR) fluorescence as a consequence of metal ion binding-induced ESIPT turn-on. Preliminary cell stain experiment was conducted and indicated the potential biological applications.

Book Molecular Expression Through Fluorescence Studies In Probe Design And Aggregation

Download or read book Molecular Expression Through Fluorescence Studies In Probe Design And Aggregation written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The present thesis entitled, "Molecular expression through fluorescence: Studies in probe design and aggregation" describes very simple bi-functional donor-acceptor poly-aromatic fluorophores that have been shown to possess distinctive properties depending on the context in which they are studied. In a sense, this work is an effort in exemplifying the inherent diversity and power of "molecular expression", with the central theme here being the phenomenon of fluorescence. The work has been divided into four chapters, each having a self-contained introduction. Chapter 1: First instance of metal ion (Zn2+) sensing exclusively at amphiphilic interfaces. (1 -pyrenyl)rnethyl-bis- [(2-pyridyl)methyl]amine (Pybpa), a simple, bi-functional fluorophore was synthesized. Pybpa has the modular design of a photoinduced electron transfer (PET) based analyte sensor. In Pybpa, a photoinduced electron transfer (PET) operates from the pyrenyl nitrogen (PyCH2-iV) to the excited pyrenyl (Py*) chromophore leading to fluorescence quenching. Zn2+ ion binding to the bis-picolyl (bpa) unit of Pybpa stops the PET process and leads to fluorescence enhancement. Thus Pybpa was able to sense Zn2+" in organic solvents. In water, however, Pybpa showed pronounced aggregation and the probe did not sense any metal ion. Surfactant micelles provide hydrophobic regions in water and the dynamic rnicellar assemblies could disrupt Pybpa aggregates. Pybpa monomers solubilized in micelles were responsive to Zn2+ in the low micro molar concentration range. The metal ion sensing on micelles was reflective of the charge of the interface. The sensing is negligible on cationic surface (CTAB), moderate on negatively charged surface (SDS micelles) and is the most efficient on neutral interface provided by TWEEN-20 micelles. With the Pybpa 'sensor*, no sensing is possible in water and hence the sensing is exclusive to the interface. Pybpa doped in membranous aggregates like phosphatidylcholine (PC) lipid bilayers, ex.

Book Photoinduced Electron Transfer in Rigid Solution

Download or read book Photoinduced Electron Transfer in Rigid Solution written by Michael Arthur Kahlow and published by . This book was released on 1983 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Fluorescent Photoinduced Electron Transfer PET Sensors for Protons

Download or read book Fluorescent Photoinduced Electron Transfer PET Sensors for Protons written by Risper Nyabeta and published by . This book was released on 2007 with total page 50 pages. Available in PDF, EPUB and Kindle. Book excerpt: