Download or read book Synthesis and Characterization of Fluorescent Molecular Rotors written by Jamie Yen-Ka Lam and published by . This book was released on 2020 with total page 155 pages. Available in PDF, EPUB and Kindle. Book excerpt: Small molecule fluorescent probes provide a non-invasive way to obtain accurate microviscosity measurements for biological analyses, especially when bulk measurements are not feasible. A family of push-pull fluorescent dyes, inspired by the benzothiazole motif of Thioflavin T, are reported, along with preliminary data on their use for visualizing long-range bacterial signaling and binding affinities for amyloids. By altering the [pi]-wire through increased conjugation and heteroatom substitution, a red-shifted ThT analogue was successfully synthesized. Synthetic analogues of previously reported fluorescent probes were also synthesized. Increasing the [pi]-wire from phenyl to naphthyl induced a bathochromic shift. It was also observed that switching from an ester to an amide altered photophysical properties in both sets of analogues. There was a slight hypsochromic shift due to the amide, likely attributed to the slight decrease in electron-withdrawing character of the acceptor group. Moreover, the emission intensity of the FRET donor decreased in the amide ratiometric system as compared to that of its ester counterpart, potentially indicating an enhancement of energy transfer between the donor and acceptor pair. These studies point towards ways to optimize the chemical structures of various fluorescent probes for specific applications.
Download or read book Synthesis and Characterization of Molecular Rotors as Viscosity Sensors and Beta Amyloid Binding Agents written by Jeyanthy Sutharsan and published by . This book was released on 2009 with total page 158 pages. Available in PDF, EPUB and Kindle. Book excerpt: It has been shown that compounds containing p-N, N, -dialkylaminobezylidene cyanoacetate motif can serve as fluorescent non-mechanical viscosity sensors. These compounds, referred to as molecular rotors, belong to a class of fluorescent probes that are known to form twisted intra-molecular charge-transfer complexes in the excited state. The first part of this work deals with the synthesis and evaluation of these compounds as viscosity sensors. The effects of the molecular structure and electronic density of these rotors to the emission wavelength, fluorescence intensity and viscosity sensitivity are presented. The second part of this work deals with the evaluation of molecular rotors as beta amyloid binding agents. The findings suggest that the general motif of molecular rotors can be applied to a rational design of new diagnostic tools for beta amyloid imaging in Alzheimer's disease.
Download or read book Synthesis and characterization of fluorescent stilbene based probes targeting amyloid fibrils written by Jun Zhang and published by Linköping University Electronic Press. This book was released on 2018-11-27 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt: Alzheimer’s disease (AD) is characterized by two main protein aggregate hallmarks in the brain: extracellular deposition of the amyloid-? (A?) in senile plaques and intracellular neurofibrillary tangles (NFTs) consisting of hyperphosphorylated tau protein. The past decade has seen great progress in the development of imaging probes for the non-invasive detection of A? and tau aggregates. Here positron emission tomography (PET), single-photon emission computed tomography (SPECT) and magnetic resonance imaging (MRI), are highly promising technologies for clinical diagnostics. However, as a research tool, optical imaging is superior because it is real-time, sensitive, inexpensive, not radioactive and that it in particular affords high-resolution studies both in vitro and in vivo. Fluorescent probes are especially useful for designing novel binding scaffolds for structure investigations of protein aggregates. This thesis describes design, synthesis and evaluation of a series of fluorescent probes for detection of amyloid fibrils, especially A? or tau aggregates in vitro. Firstly, trans-stilbenoid vinylbenzene-1,2-diol with benzene, naphthalene, anthracene, and pyrene are investigated with respect to their photophysical properties free in solution and when bound to amyloid fibrils, including time-resolved fluorescence measurements. It is noted that the extended conjugated systems retained the amyloid targeting properties of the probes and both the anthracene and pyrene moieties extensively enhanced the fluorescence intensity and prolonged lifetimes. Secondly, the synthesis of two molecules, Py1SA and Py2SA, based on pyrene linked to salicylic acid via a trans-stilbene C = C bond is presented. The compounds show strikingly different emission spectra when bound to preformed A?1-42 fibrils as well as to fibrils from four other distinct proteins. Additionally, excited state intramolecular proton transfer (ESIPT) coupled-charge transfer (ICT) is observed for the anionic form of the probes in polar solvents. This is likely the reason for the spectral differences of the probes when bound to amyloid fibrils. Moreover, the synthesis of a further development of the Congo red analogue X-34 [2,5-bis(4’-hydroxy-3’-carboxy-styryl) benzene] by rational design and synthesis is described. Full photophysical characterization was performed, including recording absorbance and fluorescence spectra, Stokes shift, quantum yield and fluorescence lifetimes. All ligands displayed high affinity towards recombinant amyloid fibrils of A?1-42 and tau as well as selectivity towards the corresponding disease-associated protein aggregates in human post mortem AD tissue. Lastly, the synthesis of a set of 2,1,3-benzothiadiazole (BTD)-based ligands with different conjugated spacers and variable patterns of OH substitutions of bis-styryl-BTD prototypes were developed. A? binding affinities (A?1-42 and A?1-40 fibrils) and the specificity towards A? plaques of all ligands were determined. These findings extend the structure to activity relationships of BTD-based ligands for A? fibril binding. Throughout the studies in this dissertation, new interesting properties of small molecule fluorescence probes have been discovered and analyzed. This knowledge should facilitate the development of noninvasive probes for early detection of Alzheimer's disease and to distinguish different A? fibril polymorphs.
Download or read book Systematic Exploration of Indolizine Based Small Fluorescent Molecules written by Youngjun Lee and published by Springer. This book was released on 2018-08-16 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis describes an in-depth study of an indolizine-based fluorophore, from understanding of its structure-photophysical property relationship to its application as a useful biological reporter. Organic fluorophores have been extensively used in the field of molecular biology owing to their excellent photophysical property, suitable cell permeability, and synthetic flexibility. Understanding of the structure-photophysical property relationship of a given fluorophore often paves the road to the development of valuable molecular probes to visualize and transcribe biological networks. In this thesis, respective chapters deal with molecular design, organic synthesis, structure-property analysis, and quantum-mechanical interpretation of unexplored family of indolizine-based molecules. This systematic exploration has led to rational development of a new microalgae lipid droplet probe, colorful bioorthogonal fluorogenic probes, and a bright mitochondrial probe, working under live cell conditions. Harnessing the optical properties of a given fluorophore has been an important topic for a couple of decades, both in industry and in academia. This thesis provides useful insights for the improvement and development of unique small fluorescent materials, or optical materials.
Download or read book Synthesis and Characterization of Salicylideneaniline Functionalized Molecular Rotors written by Ira Owen Staehle and published by . This book was released on 2014 with total page 250 pages. Available in PDF, EPUB and Kindle. Book excerpt: Artificial molecular machines have drawn much interest over the past twenty years. Several physical organic chemists have been actively involved in the study and development of different types of molecular machines. In nature many biological macromolecules have the ability to act as "molecular machines" and generate work. The most well known example of this is ATPsynthase, which functions by rotation of a central stock in order to convert ADP to ATP. These biological "molecular machines" are typically highly complex and consist of several subunits. However it is in this complexity that the function of these biological machines is manifested. In order to attain this level of complexity in artificial molecular machines, a gradual development of concepts and a deeper understanding of intermolecular interactions are required. Several molecular machine motifs have been identified and further functionality has been explored by many physical organic chemists, incorporating useful material properties. One way to create artificial molecular machines is by controlling non-brownian motion. A common motif is a system that has two distinct energy states that can interconvert between one another in response to an external stimulus. These types of molecular machine motifs can be used for generating materials that are capable of energy harnessing. Research in the Garcia-Garibay group has focused on the use of light as an external stimulus to facilitate a conformational change between two distinct states in a molecular rotor. Chapter 2 of this thesis will discuss the functionalization of molecular rotors with salicylideneanilines rotators. In work done in collaboration with Dr. Braulio Rodriguez-Molina, three different photoresponsive molecular rotors were synthesized, characterized, and crystallized. The photochromism of these solids was tested, with all systems converting from the low energy cis-enol to the transient trans-keto. The best performing of these three different molecular rotors was identified by the generation of the most trans-keto upon photoexcitation. A deuterated rotator analog was synthesized and the activation energy for rotation in the solid state was determined. Prior to this work, the preferred isomerization pathway for salicylidenenanilines was through a bicycle pedal mechanism, which does not account for rotation. The ssNMR data for the deuterated analog indicated that isomerization could also occur through rotation. Chapters 3 and 4 will discuss the functionalization of molecular rotors with salicylideneanilines stators to act as potential molecular brakes. In chapter 3, an amino substituted stator was synthesized and characterized. Crystallization proved challenging due to the preference of these compounds for the formation of spherulites, which are radial fibrous microcrystalline aggregate structures. Nonetheless, solid-state photochromism of the spherulites was determined for both systems by diffuse reflectance with the generation of a transient trans-keto form after photoexcitation. In chapter 4, an ester-substituted stator was synthesized and characterized. Single crystals could not be obtained and ssNMR was utilized to explore both the photochromism and thermochromism of the salicyladenanilines. In chapter 5 of this thesis, I will discuss the synthesis and characterization of tetra-substituted salicylideneaniline adamantanes. Adamantanes are unique because they are the simplest diamonds and provide a rigid framework with minimal stress. Furthermore, tetra-substitution of adamantane generates a tetrahedral geometry around the adamantane core. Two adamantane systems were synthesized and single crystals were grown. However, only the connectivity was determined, due to poor quality crystals. These generated molecules could have up to 64 isomers, depending on the conformations of the four salicylideneanilines moieties. The photochromism of these solids was then tested with both systems generating the transient trans-keto species.
Download or read book Towards Molecular Machines and Switches in the Solid State written by Tinh-Alfredo V. Khuong and published by . This book was released on 2001 with total page 194 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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.
Download or read book Synthesis of a Pyridinium Molecular Rotor written by Karlie Miller and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Known molecular rotors are already being used, but there are flaws that do not make these rotors universal. It is necessary to study how they are currently being used and how well they are performing their tasks. Molecular rotors are being used to study proteins: from their expression levels to their degradation in live cells. Old techniques of fluorescent probes were not very desirable because it was an irreversible process. Using a molecular rotor to track the proteins’ function is no longer irreversible because the rotor can be controlled. A molecular rotor, that has fluorescence that can be turned on or off would be able to detect more than before. Previous probes could only detect protein expression level and activity. The use of molecular rotors, over other fluorescent probes, can lead to the detection of protein degradation, translocation, and inhibition. In order for molecular rotors to be included in cells to detect these protein levels, they must be cell permeable.
Download or read book Design Synthesis and Characterization of Fluorescent Hyperbranched Polyglycerols and Organic Nanoparticles with Covalently Bound Anti fading Agents written by and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Design Synthesis and Characterization of Mechanosensitive Dual Fluorescent Dyes as Potential Probes for Biological Applications written by Susantha Ganegamage and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Chapter 3 of this dissertation explores a hypothesis that leverages the seesaw photophysical model for N-aryl (2,3- and 1,8-) naphthalimides. The Heagy group initially developed this model to understand the dual fluorescence effect concerning the electron donor or electron-withdrawing substituents. This study envisions the design and synthesis of novel dual fluorescence molecules for a new class of N-aryl-phenanthridinone dyes. The applied photophysical model further investigates these dyes with a substitution pattern opposite naphthalimide systems. Interestingly, predictive computational modeling shows that the substituent pattern, used previously for 2,3-naphthalimides, relies on these groups getting placed on rings in opposite positions for N-aryl-phenanthridinones. Chapter 4, provides an overall conclusion of the and future directions for both parts of the research. In chapter 5, a complete description of experimental data is provided for the characterization of all the dye systems presented. This data includes a detailed synthesis procedure, characterization, purity analysis by HPLC, absorptivity calculation, fluorescence lifetime measurements, quantum yield determination, biological evaluation and fluorescence titration.
Download or read book Fluorescent Methods to Study Biological Membranes written by Yves Mely and published by Springer Science & Business Media. This book was released on 2012-10-10 with total page 484 pages. Available in PDF, EPUB and Kindle. Book excerpt: Biological membranes play a central role in cell structure, shape and functions. However, investigating the membrane bilayer has proved to be difficult due to its highly dynamic and anisotropic structure, which generates steep gradients at the nanometer scale. Due to the decisive impact of recently developed fluorescence-based techniques, tremendous advances have been made in the last few years in our understanding of membrane characteristics and functions. In this context, the present book illustrates some of these major advances by collecting review articles written by highly respected experts. The book is organized in three parts, the first of which deals with membrane probes and model membranes. The second part describes the use of advanced quantitative and high-resolution techniques to explore the properties of biological membranes, illustrating the key progress made regarding membrane organization, dynamics and interactions. The third part is focused on the investigation of membrane proteins using the same techniques, and notably on the membrane receptors that play a central role in signaling pathways and therapeutic strategies. All chapters provide comprehensive information on membranes and their exploration for beginners in the field and advanced researchers alike.
Download or read book Introduction to Fluorescence Sensing written by Alexander P. Demchenko and published by Springer Nature. This book was released on 2020-12-01 with total page 673 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides systematic knowledge of basic principles in the design of fluorescence sensing and imaging techniques together with critical analysis of recent developments. Fluorescence is the most popular technique in chemical and biological sensing because of its ultimate sensitivity, high temporal and spatial resolution and versatility that enables imaging within the living cells. It develops rapidly in the directions of constructing new molecular recognition units, new fluorescence reporters and in improving sensitivity of response up to detection of single molecules. Its application areas range from control of industrial processes to environment monitoring and clinical diagnostics. Being a guide for students and young researchers, it also addresses professionals involved in active basic and applied research. Making a strong link between education, research and product development, this book discusses prospects for future progress.
Download or read book Advanced Fluorescence Reporters in Chemistry and Biology II written by Alexander P. Demchenko and published by Springer Science & Business Media. This book was released on 2010-09-08 with total page 461 pages. Available in PDF, EPUB and Kindle. Book excerpt: With contributions by numerous experts
Download or read book Synthesis of Fluorescent Molecules for the Detection of Nerve Agents and Systhesis of Novel Pyrazolo and Isoxazolo Quinoline Derivatives as Potential Drugs written by Rakesh Kumar Sit and published by . This book was released on 2009 with total page 338 pages. Available in PDF, EPUB and Kindle. Book excerpt: The main focus of chapters I and II of this dissertation is the synthesis and characterization of novel materials that will have high specificity and sensitivity for the detection of highly toxic organophosphate and organophosphonate nerve agents. The study was divided into two main sections, synthesis of quinolinone and 4-aminonaphthalimide derivatives, and binding studies of synthesized target molecules with nerve agent mimics, DCP and DFP. Nine quinolinone target molecules (TR-1, TR-2, TR-3, TR-4, TR-5, 8, 32, 9, and 10) were synthesized, and binding studies of these molecules with nerve agent mimic were also carried out. All the molecules containing the Schiff base moiety (e.g. TR-1, TR-2, TR-3 and TR4) undergo protonation upon attempted reaction with DCP. On the other hand, 7-dimethylamino-4-methyl-2-oxo-1,2-dihydroquinoline-3-carbaldehyde oxime (8) react with nerve agent mimic DCP during reaction studies. Three molecules containing functionalized tethers (TR-4S, TR-5S, and TR-1C) were synthesized so that they can bind to anodic aluminum oxide (AAO) with the help of covalent bonds in order to fabricate sensors for nerve agents. Two 4-aminonaphthalimide dyes, the lithium salt of lucifer yellow (38) and the potassium salt of lucifer yellow 43, were also synthesized successfully. Reactions of nerve agent mimic DCP with AAO which had been impregnated with 38 were studied by fluorescence spectroscopy. Twenty-seven other novel compounds, beside target molecules, were generated in the process of synthesizing quinolinone and 4-aminonaphthalimide target molecules. Chapter III of this dissertation deals with the synthesis of novel pyrazolo and isoxazolo quinoline derivatives as potential medicinal agents. Four pyrazolo and isoxazolo quinoline derivatives (51, 53, 54 and 55) were synthesized and are yet to be tested for the antiviral activity. Nine novel compounds were generated in the synthetic routes described in this chapter.
Download or read book Fluorescent Analogs of Biomolecular Building Blocks written by Marcus Wilhelmsson and published by John Wiley & Sons. This book was released on 2016-03-16 with total page 448 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fluorescent Analogs of Biomolecular Building Blocks focuses on the design of fluorescent probes for the four major families of macromolecular building blocks. Compiling the expertise of multiple authors, this book moves from introductory chapters to an exploration of the design, synthesis, and implementation of new fluorescent analogues of biomolecular building blocks, including examples of small-molecule fluorophores and sensors that are part of biomolecular assemblies.
Download or read book Synthesis and Characterization of Two photon Fluorescent Chromophores for Biological Imaging MS written by Judith M. Lavin and published by . This book was released on with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
