Chemistry Commons^™

Preparation And Study Of Bacterial Membrane Models, Enoch Asimbisa

Electronic Theses and Dissertations

Fuel molecules are organic solvents that have disruptive effects on the bacterial membrane. This is a significant barrier in biofuel production, as it limits the fuel concentration that can be achieved through fermentation. One potential way of overcoming this barrier is to identify lipid compositions that can better withstand solvent stress, for which it is important to understand how organic solvents disrupt the membrane. Use of biophysical characterization techniques to quantify physical properties like fluidity and thickness will enable us to understand the mechanism by which solvents disrupt membranes. Native membranes are very complex, and we sought to develop in-vitro …

Synthesis And Characterization Of Re(I) Tricarbonyl Complexes Of 1,8-Naphthalimide, Priyanka Jagadeesa Prabhu

Electronic Thesis and Dissertation Repository

1,8-Naphthalimide fluorophores with amino-substituents absorb and emit in the visible region. The photophysical properties of this class of fluorophores can be modulated by altering the degree of Intramolecular Charge Transfer (ICT) in the excited state. Thus, several metal complexes with the 1,8-naphthalimide motif have been developed as cell imaging agents. In this project, four 1,8-naphthalimide ligands were synthesized by incorporating rigid linkers. Among these, three ligands also allowed the extension of π-conjugation to the naphthalimide moiety. In addition, a ligand was also synthesized without the use of a linker. Re(I) tricarbonyl complexes of these ligands were also synthesized and their …

Part I: Development Of Small-Molecule-Based Probes For The Vitamin D Receptor; Part Ii: Development Of A Scalable Manufacturing Process For Orcein Dye, Tania Roseann Mutchie

Theses and Dissertations

PART I:The vitamin D receptor (VDR) is a ligand-dependent transcription factor and member of the nuclear hormone receptor superfamily. VDR is expressed in the epithelia of endocrine organs, digestive system, bronchi, kidneys, and thymus, as well as being present in leukocytes and bone cells. Cell proliferation, cell differentiation, and immunomodulation, along with calcium and phosphate homeostasis, are all processes regulated by the receptor. Within the cell, VDR can be membrane-bound or located in the nucleus. Nuclear localization of VDR transpires following the binding of vitamin D metabolites, the most active of which is 1α,25-dihydroxyvitamin D3 (calcitriol). Within the nucleus, interactions …

Indolizine Donor-Based Dyes For Applications In Fluorescence Biological Imaging, William Meador

Honors Theses

NIR emissive fluorophores are intensely researched due to their potential to replace modern imaging procedures. Many molecular strategies have been employed in the literature to optimize fluorophores for deeper NIR absorption and emission, biocompatibility, and higher fluorescence quantum yields. Amongst the fluorophores studied to date, proaromatic indolizine donors are attractive alternatives to traditional alkyl amine and indoline based donors due to their 1) lower energy absorption and emission facilitated by proaromaticity, 2) large Stokes shifts due to increased dihedral angles about the π-system, 3) ease of functionalization and capacity for bioconjugation at the phenyl ring, and 4) potential for further …

The Development Of Metal Complexes As Components Of Fluorescent And Nuclear Imaging Probes, William Turnbull

Electronic Thesis and Dissertation Repository

The advent of molecular imaging as a discipline has drastically improved our ability to understand the biochemical and cellular events that drive life, death and disease. This thesis will document the discovery of new metal chelators for Re/^99mTc, new methods of incorporating these metals into peptide structures, as well as new fluorescent compounds. These novel methods and compounds may be used in the development of molecular imaging probes for single photon emission computed tomography (SPECT) and optical imaging techniques, with applications for differentiating cancerous tissue from benign and healthy.

Chapter 2 discusses the development of a dual modality …

Tumor-Targeting Fluorinated Phthalocyanines For Theranostic Applications, Erik Nathaniel Carrión

Seton Hall University Dissertations and Theses (ETDs)

Hydrocarbon-based therapeutics and imaging agents are prone to chemical oxidation and degradation resulting in loss of activity and limited functional utility. Thus, more material is required to achieve long-lasting therapeutic effects. Phthalocyanines (Pcs) and their metal complexes (PcMs) can be utilized as prodrugs requiring only renewable energy resources namely, air and light, for cancer therapy and diagnostic (theranostic) applications related to photodynamic therapy (PDT). Replacement of labile C-H bonds in the Pc scaffold with a combination of fluoro and perfluoroisopropyl groups has resulted in a stable yet reactive oxidation catalyst of biological significance and importance. For example, F₆₄PcZn, …

Higher Energy Gap Control Of Fluorescence In Conjugated Polymers, Chien-Hung Chiang

LSU Doctoral Dissertations

Chemo- and biosensors based on fluorescent conjugated polymer benefit from greater detection sensitivity due to amplification of the electronic perturbations produced by analyte binding. This amplification stems from the exciton-transporting properties of conjugated polymers. A conventional design paradigm relies on the analyte binding events which generate sites of lower energy relative to the polymer energy: either fluorescence quenching sites (turn-off sensors) or bathochromically shifted fluorophores (turn-on sensors). In both type sensors, the excitons migrate to the lower-energy site created by analyte binding.

This dissertation primarily focused the investigation of an alternative paradigm when analyte binding creates higher energy gap sites …

Determination Of Atrazine Concentration In Freshwaters Using Fluorescence Spectroscopy, Boniface Osei Amankona

Online Theses and Dissertations

Atrazine is the most widely used herbicides in USA, but its negative impact on aquatic ecosystem cannot be over-looked. Atrazine was traditionally determined through liquid/gas chromatography or IR spectroscopy. However, these methods are either time-consuming or costly, so fluorescence spectroscopy is investigated as a more cost and time efficient alternative. Literature value of the optimal wavelength of atrazine was found to be 350 nm emission. Experimental value for emission scanned of atrazine resulted in an optimal wavelength of 363 nm. Known and unknown concentrations of atrazine will be analyzed using fluorescence spectrophotometer to develop a calibration curve.

The calibration concentration …

From The Making To The Tuning To The Use Of Chlorins For Biomedical Applications, Junior Gonzales

Dissertations, Theses, and Capstone Projects

Chlorins are porphyrins missing a double bond. These pigments are optimal platforms for the development of novel dyes that display drug-like attributes such as photodynamic therapy (PDT) agents. More recently, it was demonstrated that chlorins can serve both as a PDT agent and as a modality for fluorescence or PET imaging. Thus, multifunctional chlorins eliminate the differences that may occur in specificity, uptake, and distribution between separate compounds or constructs for imaging and therapy. The overall goal of this dissertation is to take advantage of the reputed intrinsic attributes of chlorins as a viable tool in biomedical applications. In this …

Synthesis And Fluorescent Properties Of A New Flavonoid Compound, Ashley L. Ingle

Williams Honors College, Honors Research Projects

Flavonoids are highly luminescent compounds that are used in diagnosing and treating certain diseases.They are composed of two aromatic rings (ring A and ring B) and a six-membered heterocyclic pyran ring (ring C) that contains a carbonyl and hydroxyl group, which are responsible for unique photophysical characteristics associated with flavonoids. The target flavonoids (compound 1, or 1, and compound 2 or 2) were synthesized, purified and characterized by NMR spectroscopy. The photophysical properties of the flavonoid were investigated in varying solvents by using UV-vis and fluorescence spectroscopy. Such properties include Excited State Intramolecular Proton Transfer (ESIPT), Intramolecular Charge …

Influence Of Shelling Temperature And Time On The Optical And Structural Properties Of Cuins2/Zns Quantum Dots, Colette Robinson

Graduate Theses and Dissertations

CIS/ZnS core/shell QDs are an important class of nanomaterials for optoelectronic, photovoltaic and photoluminescence applications. They consist of lower toxicity materials than the prototypical II-VI Cd-based QDs and show long fluorescence lifetimes, which generates prospective in biological imaging applications. It is vital to develop reproducible synthetic methods for this new class of nanomaterials in order to maintain small sizes with high QYs. CIS core QDs have been shelled with ZnS at various temperatures from 90-210°C for reaction times ranging from 20-140 minutes to examine the role of thermodynamics and kinetics on the shell growth. Using HR-TEM and ICP-MS, it was …

Photochemical Tools For Fluorescent Labeling Of Endogenous Proteins, Stephen T. Mccarron

Doctoral Dissertations

The study of the dynamic movements of membrane bound proteins is typically achieved through an exogenously applied fluorescent tag or genetic modification of a receptor of interest to spatiotemporally monitor protein location. Techniques often used for labeling proteins include overexpression of a fluorescent protein such as GFP fused to a target protein or the application of antibodies. These methods benefit from superb specificity towards a receptor of interest, but may impose unforeseen consequences when studying natural protein movements. Thus, it is advantageous to development small, modular probes that would allow for visualization of endogenous membrane bound receptors in a minimally …

Design And Development Of Bodipy-Based Fluorescent Probes For Sensing And Imaging Of Cyanide, Zn (Ii) Ions, Lysosomal Ph And Cancer Cells, Jingtuo Zhang

Dissertations, Master's Theses and Master's Reports - Open

BODIPY (4,4-Difluoro-3a,4a-diaza-s-indacene) dyes have gained lots of attention in application of fluorescence sensing and imaging in recent years because they possess many distinctive and desirable properties such as high extinction coefficient, narrow absorption and emission bands, high quantum yield and low photobleaching effect. However, most of BODIPY-based fluorescent probes have very poor solubilities in aqueous solution, emit less than 650 nm fluorescence that can cause cell and tissue photodamages compared with bio-desirable near infrared (650-900 nm) light. These undesirable properties extremely limit the applications of BODIPY-based fluorescent probes in sensing and imaging applications. In order to overcome these drawbacks, we …

Molecular Probes For The Detection Of Zn2+ And Fe3+ Ions, Erendra Manandhar

Dissertations

A number of molecular probes have been designed and synthesized for the detection of Zn²⁺ and Fe³⁺ ions. Two types of functional groups have been incorporated into the molecular scaffolds to utilize different fluorescent mechanisms. The first class of receptors contains a pyrene moiety. These molecular probes use the excimer mechanism for the detection of Zn²⁺ ion. The probes work well in an organic solvent with a detection limit of 20 nM (one ppb). Alternatives are made to make them water soluble, but this proved to be difficult. An interesting ion-induced self-assembly system will also be discussed. …

Synthesis And Characterization Of Fluorophores For The Detection Of Lanthanides And Actinides, Robinson I. Roacho

Open Access Theses & Dissertations

A series of fluorophores based in the boron dipyrromethene (BODIPY) family were synthesized and characterized. These fluorophores have the capacity of being introduced to a carbamoyl methyl phosphine oxide (CMPO) lanthanide/actinide extractant. These blue, green and red emission fluorophores show high thermal/moisture stability and high fluorescence efficiencies. The fluorescence intensity seems to be dependent on the restricted rotation about the C(8)-C bond in 8-Ph-BODIPY. By taking advantage of this feature, a hydroxyl- containing BODIPY with high fluorescence intensity was synthesized to be incorporated to a CMPO carboxylic acid via esterification. Unfortunately, we did not observe an optical response upon the …

Progress Toward Synthesis Of Molecular Beacons Incorporating Dabcyl Analog Quenchers, Christie M. Ettles

Electronic Thesis and Dissertation Repository

Progress toward the synthesis of molecular beacons containing analogs of the universal quencher 4-(4'-dimethylaminophenylazo)benzoic acid (DABCYL) has been made. A synthetic methodology has been developed for the differential labeling of a PNA molecular beacon with quencher and fluorophore moieties. A DABCYL analog diarylazo compound and three small fluorescent molecules have been derivatized with terminal alkyne groups for incorporation into azide-decorated PNA oligomers by on-resin “click” chemistry. An optimized on-resin procedure was used to determine the viability of the fluorophores and quencher for incorporation into PNA.

The synthesis of a pyrrolocytidine phosphoramidite containing a diarylazo DABCYL analog moiety was undertaken with …

Development Of A Bio-Molecular Fluorescent Probe Used In Kinetic Target-Guided Synthesis For The Identification Of Inhibitors Of Enzymatic And Protein-Protein Interaction Targets, Katya Pavlova Nacheva

USF Tampa Graduate Theses and Dissertations

Abstract

Fluorescent molecules used as detection probes and sensors provide vital information about the chemical events in living cells. Despite the large variety of available fluorescent dyes, new improved fluorogenic systems are of continued interest. The Diaryl-substituted Maleimides (DMs) exhibit excellent photophysical properties but have remained unexplored in bioscience applications. Herein we present the identification and full spectroscopic characterization of 3,4-bis(2,4-difluorophenyl)-maleimide and its first reported use as a donor component in Forster resonance energy transfer (FRET) systems. The FRET technique is often used to visualize proteins and to investigate protein-protein interactions in vitro as well as in vivo. The analysis …

Design And Syntheses Of Fluorescent Cytosine Analogues, David W. Dodd

Electronic Thesis and Dissertation Repository

The avid hybridization of peptide nucleic acid (PNA) to DNA and RNA along with the molecule’s biological stability has led it to be used in both antisense and antigene capacities. PNA acts against translation via a steric blockade mechanism. It is therefore reasonable to assume that increased heteroduplex stability could lead to increased potency. Two ways of doing this were explored. I) N-Terminal attachment of a platinous chloride chelating moiety to PNA complementary to Xenopus noggin was synthesized with the objective of selective, covalent platination of the target transcript in vivo. Phenotypes consistent with knockdown of the selected …