Download or read book Fluorescent Photoinduced Electron Transfer PET Proton Sensors written by Risper Nyabeta and published by . This book was released on 2007 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Fluorescent Photoinduced Electron Transfer PET Sensor for Cations with a Separate PET Channel to Suppress Proton Signals written by Sunpun Pathirana and published by . This book was released on 2008 with total page 58 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Novel Fluorescent Sensors for Cations with Additional PET Pathways to Suppress Signals from Protons written by Lesly C. Gomez and published by . This book was released on 2015 with total page 64 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fluorescent Photoinduced Electron Transfer PET Cation Sensors Derived from Natural Products written by Kenny Loo and published by . This book was released on 2005 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Advanced Concepts in Fluorescence Sensing written by Chris D. Geddes and published by Springer Science & Business Media. This book was released on 2007-05-24 with total page 333 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the last decade, fluorescence has become the dominant tool in biotechnology and medical imaging. These exciting advances have been underpinned by the advances in time-resolved techniques and instrumentation, probe design, chemical / biochemical sensing, coupled with our furthered knowledge in biology. Complementary volumes 9 and 10, Advanced Concepts of Fluorescence Sensing: Small Molecule Sensing and Advanced Concepts of Fluorescence Sensing: Macromolecular Sensing, aim to summarize the current state of the art in fluorescent sensing. For this reason, Drs. Geddes and Lakowicz have invited chapters, encompassing a broad range of fluorescence sensing techniques. Some chapters deal with small molecule sensors, such as for anions, cations, and CO2, while others summarize recent advances in protein-based and macromolecular sensors. The Editors have, however, not included DNA or RNA based sensing in this volume, as this were reviewed in Volume 7 and is to be the subject of a more detailed volume in the near future.
Download or read book Fluorescent PET photoinduced Electron Transfer Sensing with Simultaneous Indication of Position written by Juliette Roiron and published by . This book was released on 2000 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Photoinduced Electron Transfer V written by A. Albini and published by Springer. This book was released on 1993-09-22 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt: 1. P. Maslak: Fragmentations by Photoinduced Electron Transfer. Fundamentals and Practical Aspects 2. P.K. Freeman, S.A. Hatlevig: The Photochemistry of Polyhalocompounds, Dehalogenation by Photoinduced Electron Transfer, New Methods of Toxic Waste Disposal 3. J.-P. Soumillion: Photoinduced Electron Transfer Employing Organic Anions 4. A. Albini, E. Fasani, M. Mella: PET-Reactions of Aromatic Compounds 5. G. Pandey: Photoinduced Electron Transfer (PET) in Organic Synthesis 6.R.A. Bissell, A.P. de Silva, H.Q.N. Gunaratne, P.L.M. Lynch, G.E.M. Maguire, C.P. McCoy, K.R.A.S. Sandanayake: Fluorescent PET (Photoinduced Electron Transfer) Sensors
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.
Download or read book Photoinduced Electron Transfer Based Fluorescent Sensors for Metal Ion Detection written by Jason Paul Geue and published by . This book was released on 2002 with total page 382 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fluorescent Photoinduced Electron Transfer Sensing of Anions Using Charge Neutral Chemosensors written by Mark Glynn and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fluorescent Chemosensors for Metal Ions Based on Photoinduced Electron Transfer PET from Sulfur written by Mireille Vonlanthen and published by . This book was released on 2013 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Optical Sensors and Switches written by V. Ramamurthy and published by CRC Press. This book was released on 2001-07-24 with total page 540 pages. Available in PDF, EPUB and Kindle. Book excerpt: A consideration of the development of photochemical systems with functions as optical sensors or switches, discussing materials and chemical systems, technology, and applications for target molecules and optical signal multiplexing. It contains novel applications in electrogenerated chemiluminescence and supramolecular photophysics for sensing chemical and biological analytes.
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
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.
Download or read book Chemical Sensors Based on Fluorescence Turn on Mechanism by Using Excited State Intramolecular Proton Transfer written by Weihua Chen and published by . This book was released on 2012 with total page 167 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ex[c]ited state intramolecular proton transfer (ESIPT) occurs in aromatic molecules that contain hydrogen bond donor and acceptor groups located at a close distance. In the event of proton transfer, a proton migrates from one group to the other, thereby producing a tautomeric form which emits fluorescence with a large Stokes shift. My research focuses on the development of novel fluorescent sensors with an ESIPT turn-on mechanism, which intends to address some of the problems that we human being are facing today. As a starting point, we choose 2-(2'-hydroxyphenyl)benzoxazole (HBO) as a model compound which absorbs at 320 nm and emits at 500 nm. Our strategy is to design a sensor molecule in which either the H-donor or acceptor is masked to block the ESIPT pathway. Upon specific binding with the target analytes, the masked H-donor (or acceptor) can be released, thereby enabling the ESIPT. Such kind of ESIPT turn-on approaches as a sensing event trigger in chemical sensors were rarely reported in literature when we started our research in 2009. My dissertation is devoted to seek fundamental understanding on the ESIPT mechanism, and to utilize the ESIPT in chemical sensor design. First, an efficient method for constructing HBO derivatives has been developed by using palladium (II) mediated oxidative cyclization in Chapter 2. The reaction was carried out in mild conditions with easily-synthesized Schiff base as starting material and was compatible to a wide range of function groups. The Pd (II) involved in the reaction was consumed in the [beta]-hydride elimination step and regenerated in the presence of oxygen. This method opens a path for efficient construction of HBO molecules with various functional groups, which has been used throughout my research to synthesize the HBO derivatives of interest. HBO compounds often exhibit dual fluorescence in polar solvents due to rotamerism around the single bond connecting the benzoxazole to the 2'-hydroxyphenyl ring. Although the two rotamers of HBO are assumed to convert to each other through a bond rotation, the magnitude of the rotational barrier is not known in literature. By designing 2-(2',6'-dihydroxyphenyl) benzoxazole (DHBO), we incorporated two hydroxyl groups in the molecule, which allows to monitor two related hydrogen bondings, i.e. N···H-O and O···H-O, simultaneously. NMR study of DHBO over variant temperature detected two sets of OH peaks that coalescence at -20 °C. This observation led to the first estimation of rotational energy barrier for HBO derivatives (rotational barrier energy = 10.5 kcal/mol), which is described in Chapter 3. In addition, 2-D NMR and fluorescence study of compound 4-bromo-2- (4-methyl-2-benzoxazolyl)phenol revealed that the syn-rotamer is predominant in CDCl3. Pyrophosphate (PPi) is a biologically important target which is involved in many cellular processes. To selectively and sensitively detect this species over other anion, for example phosphate and ATP, is a challenging task. In chapter 4, we demonstrated that significantly improved PPi detection can be achieved by using the binuclear compound 3·2Zn, in which the proton donor is masked to disable ESIPT. Unique geometry of the designed binuclear compound allows 3·2Zn to selectively accommodate a PPi molecule into the two zinc centers, thereby initiating the thermodynamically favored Zn-O bond cleavage to enable ESIPT upon PPi binding. Because of its high selectivity over other anions, it can detect PPi released from a PCR experiment and has the potential to be further developed for DNA pyrosequencing. In addition we also have synthesized the mono nuclear compounds 8·Zn in order to understand the mechanism of this sensing event. Palladium catalyzed reactions are widely used in organic synthesis such as Suzuki-Miyaura coupling, Heck coupling and Buchwald-Hartwig reaction. To analyze the residual palladium (often in the form of Pd(II)) in the final product is important because it may be a health hazard. The government threshold for palladium in drugs is 5-10 ppm. In Chapter 5, we examined how the substituents at the 5 position of the phenol ring affect the Pd(II) promoted oxidative cyclization and we found electron withdrawing group can enhance the reaction rate following a linear Hammett plot pattern. Based on these findings, a strong electron withdrawing group dicyanomethyl was introduced at the 5 position to obtain a new sensor for Pd(II). The sensor itself was non-fluorescent, however, upon addition of Pd(II) in acetonitrile/water at room temperature, it underwent oxidative cyclization to form the benzoxazole ring, therefore turning on the ESIPT fluorescence. The sensor showed high selectivity and was able to detect Pd(II) in the presence of other competing metal ions. Serendipitously, the sensor gave an emission band in the near-infrared (NIR) region with the peak maximum at 780 nm, thus providing the first NIR sensor for palladium detection.
Download or read book Fluorescent Chemosensors for Ion and Molecule Recognition written by Anthony W. Czarnik and published by . This book was released on 1993 with total page 256 pages. Available in PDF, EPUB and Kindle. Book excerpt: From an August 1992 symposium in Washington, D.C., 13 papers report on research into developing fluorescent chemosensors for devices to monitor several critical parameters of blood composition in real time. They aim at opening communication between the clinicians and researchers who want such devices and the scientists and engineers who could develop them. Among the topics are the synthesis and study of crown ethers with alkali- metal-enhanced fluorescence, the tunable florescence of some macrocyclic anthracenophanes, and fluorescent probes in studies of proteases. Annotation copyright by Book News, Inc., Portland, OR
