Physical Sciences and Mathematics Commons^™

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 …

Fabrication, Characterization, And Application Of Carbon Nanoparticles For The Detection Of Heavy Metal Ions In Aqueous Media, Aaron Michael Simpson

MSU Graduate Theses

This research set out to develop a method for producing Carbon nanoparticles (CNPs) from glycerol and use them to detect Cu2+, Hg2+, and Pb2+ ions in aqueous solution. Three synthesis methods were developed using the following mixtures: (1) glycerol and silica, (2) glycerol, silica, and H3PO4, and (3) glycerol with H3PO4. The structure of the particles was characterized using a variety of spectroscopic techniques. Size distributions were obtained from scanning electron microscopy images. The particles were spherical with average diameters of 66, 58, and 89 nm respectively and believed to consist of a carbon core with carboxylic acid and alcohol …

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 …

Charge-Mediated Recognition Of N-Terminal Tryptophan In Aqueous Solution By A Synthetic Host, Meghan Bush, Nicole Bouley, Adam Urbach

Adam R Urbach

The molecular recognition of peptides and proteins in aqueous solution by designed molecules remains an elusive goal with broad implications for basic biochemical research and for sensors and separations technologies. This paper describes the recognition of N-terminal tryptophan in aqueous solution by the synthetic host cucurbit[8]uril (Q8). Q8 is known to form 1:1:1 heteroternary complexes with methyl viologen (MV) and a second aromatic guest. Here, the complexes of Q8·MV with (i) the four natural aromatic α-amino acids, (ii) four singly charged tryptophan derivatives, and (iii) four tryptophan-containing tripeptides were characterized by isothermal titration calorimetry, mass spectrometry, and UV−visible, fluorescence, and …

Sequence-Specific, Nanomolar Peptide Binding Via Cucurbit[8]Uril-Induced Folding And Inclusion Of Neighboring Side Chains, Lauren C. Smith, David G. Leach, Brittney E. Blaylock, Omar A. Ali, Adam R. Urbach

Adam R Urbach

This paper describes the molecular recognition of the tripeptide Tyr-Leu-Ala by the synthetic receptor cucurbit[8]uril (Q8) in aqueous buffer with nanomolar affinity and exceptional specificity. This combination of characteristics, which also applies to antibodies, is desirable for applications in biochemistry and biotechnology but has eluded supramolecular chemists for decades. Building on prior knowledge that Q8 binds to peptides with N-terminal aromatic residues, a library screen of 105 peptides was designed to test the effects of residues adjacent to N-terminal Trp, Phe, or Tyr. The screen used tetramethylbenzobis(imidazolium) (MBBI) as a fluorescent indicator and resulted in the unexpected discovery that MBBI …

The Nicotine Metabolite, Cotinine, Alters The Assembly And Trafficking Of A Subset Of Nicotinic Acetylcholine Receptors, Ashley M. Fox, Faruk H. Moonschi, Christopher I. Richards

Chemistry Faculty Publications

Exposure to nicotine alters the trafficking and assembly of nicotinic receptors (nAChRs), leading to their up-regulation on the plasma membrane. Although the mechanism is not fully understood, nicotine-induced up-regulation is believed to contribute to nicotine addiction. The effect of cotinine, the primary metabolite of nicotine, on nAChR trafficking and assembly has not been extensively investigated. We utilize a pH-sensitive variant of GFP, super ecliptic pHluorin, to differentiate between intracellular nAChRs and those expressed on the plasma membrane to quantify changes resulting from cotinine and nicotine exposure. Similar to nicotine, exposure to cotinine increases the number of α4β2 receptors on the …

Source-Specific Molecular Signatures For Light-Absorbing Organic Aerosols, Amanda Susan Willoughby

Chemistry & Biochemistry Theses & Dissertations

Organic aerosols (OA) are universally regarded as an important component of the atmosphere based on quantitative significance as well as the far-reaching impact they have on global climate forcing and human health. Despite the acknowledged importance, OA amounts and impacts remain the largest uncertainties regarding radiative forcing estimates. Incomplete chemical characterization of aerosol organic matter (OM) and a lack of concrete source apportionment is a major source of this uncertainty. The primary focus of this study is to provide much needed molecular details regarding ambient OA from key emission sources, and establish links between molecular and optical properties.

Complete chemical …

Biocompatible Flavone-Based Fluorogenic Probes For Quick Wash-Free Mitochondria! Imaging In Living Cells, Bin Liu, Mickey Shah, Ge Zhang, Qin Liu, Yi Pang

Yi Pang

Mitochondria, vital organelles existing in almost all eukaryotic cells, play a crucial role in energy metabolism and apoptosis of aerobic organisms. In this work, we report two new flavone-based fluorescent probes, MC-Mito1 and MC-Mito2, for monitoring mitochondria in living cells. These two probes exhibit remarkably low toxicity, good cell permeability, and high specificity; these probes complement the existing library of mitochondrial imaging agents. The new dyes give nearly no background fluorescence, and their application does not require tedious postwashing after cell staining. The appreciable tolerance of MC-Mito2 encourages a broader range of biological applications for understanding the cell degeneration and …

Biocompatible Flavone-Based Fluorogenic Probes For Quick Wash-Free Mitochondria! Imaging In Living Cells, Bin Liu, Mickey Shah, Ge Zhang, Qin Liu, Yi Pang

Ge Zhang

Mitochondria, vital organelles existing in almost all eukaryotic cells, play a crucial role in energy metabolism and apoptosis of aerobic organisms. In this work, we report two new flavone-based fluorescent probes, MC-Mito1 and MC-Mito2, for monitoring mitochondria in living cells. These two probes exhibit remarkably low toxicity, good cell permeability, and high specificity; these probes complement the existing library of mitochondrial imaging agents. The new dyes give nearly no background fluorescence, and their application does not require tedious postwashing after cell staining. The appreciable tolerance of MC-Mito2 encourages a broader range of biological applications for understanding the cell degeneration and …

Structural And Functional Analysis Of The Reaction Center Complexes From The Photosynthetic Green Sulfur Bacteria, Guannan He

Arts & Sciences Electronic Theses and Dissertations

The reaction center (RC) complex of the green sulfur bacterium Chlorobaculum tepidum is composed of the Fenna-Matthews-Olson (FMO) antenna protein and the reaction center core (RCC) complex. The RCC complex has four subunits: PscA, PscB, PscC, and PscD. The structure of the intact and functional FMO-RCC complex was studied by chemically cross-linking the purified sample followed by biochemical and spectroscopic analysis. The interaction sites of the cross-linked complex were also studied using LC-MS/MS. A structural model is proposed based on those results. In addition, the RCC complexes were purified, both the PscA-PscC complex from the Chlorobaculum tepidum and the PscA-PscB …

Studies Of Optical And Electronic Properties Of Nanoparticles For Solar Energy Conversion, Caitlin Kruse, Libai Huang

The Summer Undergraduate Research Fellowship (SURF) Symposium

The higher energy needs for today's technological society requires sustainable and renewable energy source, such as solar energy. This study focuses on using semiconducting quantum dots and fluorescent dyes as light absorbers for solar energy conversion devices such as solar cells. Quantum dots are small nanocrystals (usually 2-10 nm in diameter) with tunable absorbing properties. The smaller the dot, the shorter the wavelength being absorbed. Quantum dots are extremely efficient light absorbers and emitters. Fluorescent dyes have a high quantum yield. In order to examine the energy conversion, cadmium selenide (CdSe) quantum dots and Rhodamine 6G (R6G) dye were spin …

A Structurally-Tunable 3-Hydroxyflavone Motif For Visible Light-Induced Carbon Monoxide-Releasing Molecules (Corms), Stacey N. Anderson, Jason M. Richards, Hector J. Esquer, Abby D. Benninghoff, Atta M. Arif, Lisa M. Berreau

Chemistry and Biochemistry Faculty Publications

Molecules that can be used to deliver a controlled amount of carbon monoxide (CO) have the potential to facilitate investigations into the roles of this gaseous molecule in biology and advance therapeutic treatments. This has led to the development of light-induced CO-releasing molecules (photoCORMs). A goal in this field of research is the development of molecules that exhibit a combination of controlled CO release, favorable biological properties (e.g., low toxicity and trackability in cells), and structural tunability to affect CO release. Herein, we report a new biologically-inspired organic photoCORM motif that exhibits several features that are desirable in a next-generation …

Synthesis And Functionalization Of Fluorescent Quantum Dot Bioconjugates For Cellular Imaging Of Directed Gene Therapy, Jason Matthew Davis

MSU Graduate Theses

Herein, I optimize a method for synthesis and bioconjugation of water-soluble, fluorescent CdSe/ZnS quantum dots (QDs) for targeted cellular delivery of DNA. Core CdSe QDs were synthesized in high temperature organic solvents and passivated with a ZnS shell to increase quantum yield. The fluorescent QD nanoparticles were made water-soluble by enveloping them with an amphiphilic polymer. These aqueous nanoparticles were functionalized with tertiary amines to impart a positive charge, allowing electrostatic binding to negatively-charged DNA. The conjugated QDs were characterized using zeta potential and electrophoresis to gauge their ability to electrostatically bind DNA. The QDs were further modified by conjugation …

Binding-Induced, Turn-On Fluorescence Of The Egfr/Erbb Kinase Inhibitor, Lapatinib, James N. Wilson

James N Wilson

We report the photophysical properties, binding-induced turn-on emission, and fluorescence imaging of the cellular uptake and distribution of lapatinib, an EGFR/ERBB inhibitor. Lapatinib, a type II, i.e. inactive state, inhibitor that targets the ATP binding pocket of the EGFR family of receptor tyrosine kinases. DFT calculations predict that the 6-furanylquinazoline core of lapatinib should exhibit an excited state with charge transfer character and an S0 to S1 transition energy of 3.4 eV. Absorption confirms an optical tran- sition in the near UV to violet, while fluorescence spectroscopy shows that photoemission is highly sensi- tive to solvent polarity. The hydrophobicity of …

Synthetic Approaches To Flexible Fluorescent Conjugated Polymers, Tereza Vokata

FIU Electronic Theses and Dissertations

Conjugated polymers (CPs) are intrinsically fluorescent materials that have been used for various biological applications including imaging, sensing, and delivery of biologically active substances. The synthetic control over flexibility and biodegradability of these materials aids the understanding of the structure-function relationships among the photophysical properties, the self-assembly behaviors of the corresponding conjugated polymer nanoparticles (CPNs), and the cellular behaviors of CPNs, such as toxicity, cellular uptake mechanisms, and sub-cellular localization patterns.

Synthetic approaches towards two classes of flexible CPs with well-preserved fluorescent properties are described. The synthesis of flexible poly(p-phenylenebutadiynylene)s (PPBs) uses competing Sonogashira and Glaser coupling reactions …

Sequence-Specific, Nanomolar Peptide Binding Via Cucurbit[8]Uril-Induced Folding And Inclusion Of Neighboring Side Chains, Lauren C. Smith, David G. Leach, Brittney E. Blaylock, Omar A. Ali, Adam R. Urbach

Chemistry Faculty Research

This paper describes the molecular recognition of the tripeptide Tyr-Leu-Ala by the synthetic receptor cucurbit[8]uril (Q8) in aqueous buffer with nanomolar affinity and exceptional specificity. This combination of characteristics, which also applies to antibodies, is desirable for applications in biochemistry and biotechnology but has eluded supramolecular chemists for decades. Building on prior knowledge that Q8 binds to peptides with N-terminal aromatic residues, a library screen of 105 peptides was designed to test the effects of residues adjacent to N-terminal Trp, Phe, or Tyr. The screen used tetramethylbenzobis(imidazolium) (MBBI) as a fluorescent indicator and resulted in the unexpected discovery that MBBI …

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 …

Grazing Incidence X-Ray Fluorescence Measurements Of Genesis Sample 30580 For Determination Of Manganese And Nickel Fluences, Martina Schmeling, J. Davidson, P.J. Eng, J.E. Stubbs, A.J.G. Jurewicz, D.S. Burnett

Chemistry: Faculty Publications and Other Works

Genesis flight sample 30580 was analyzed by grazing incidence X-ray fluorescence spectrometry for subsequent calculation of Mn and Ni fluences.

Characterization And Photodegradation Of Dissolved Organic Matter (Dom) From A Tropical Lake And Its Dominant Primary Producer, The Cyanobacteria Microcystis Aeruginosa, Thais B. Bittar, Aron Stubbins, Armando A. H. Vieira, Kenneth Mopper

Chemistry & Biochemistry Faculty Publications

This study investigates optical and high-resolution molecular signatures and photochemical degradation of DOM from the Barra Bonita Reservoir (BB-DOM), a tropical eutrophic lake, as well as from its dominant phytoplankton species, the cyanobacteria Microcystis aeruginosa (Microcystis-DOM). Consistent with a predominantly autotrophic source, BB-DOM and Microcystis-DOM exhibited high protein-like fluorescence and contained a large number of aliphatics. Microcystis-DOM was enriched in peptide-like formulae, while BB-DOM had higher chromophoric and fluorescent DOM(CDOM and FDOM) and was enriched in moderately unsaturated formulae, indicating additions of terrigenous DOM and/or in situ processing of autochthonous material in the lake. Consistent with …

Fluorescence Monitoring And Parallel Factor Analysis Of Contaminant Mixtures In Water, Nina M. Caputo

Honors College

Pharmaceuticals and Personal Care Products (PPCPs) pollute our water systems regularly by entering the environment through inefficient methods of water treatment, ineffective sanitation and unregulated industrial and agricultural runoff. Currently, the most common methods of identifying PCPPs are expensive, time consuming and often require the aid of a trained expert. This project aims to further the methodology of utilizing fluorescence spectroscopy as a means of pollutant detection with a focus on contaminant mixtures. Four non-regulated EPA contaminants were fluoresced at compound specific EEM parameters and then again in two component mixtures to determine their limits of detection (LOD). The results …

Fluorescent Mono- And Tetra-Dansylated Cavitands: Synthesis And Acid Sensitivity, Ümi̇t İşci̇, Yunus Zorlu, Fabienne Dumoulin

Turkish Journal of Chemistry

Two fluorescent tetra- and mono-dansylated resorcinarene cavitands were prepared and fully characterized. The X-ray structure of mono-dansylated resorcinarene cavitand was obtained. Their intrinsic absorption and fluorescence properties were studied. These properties were strongly sensitive to the presence of perchloric acid, as evidenced by the appearance of isobestic points upon protonation of the dansyl dimethylamino functions. The decreasing of the fluorescence emission intensity upon titration with perchloric acid was explained by the excited state interactions between the dansyl groups of the resorcinarene. Fluorescence quantum yields (\Phi _F) of mono- and tetra-dansylated cavitands and the reference compound were determined using dansyl chloride …

Gaseous And Dissolved Oxygen Sensing With Stabilized Pyrene In Ionic Liquid Modified Electrospun Slides, Özlem Öter, Gülhan Sabanci Şahi̇n

Turkish Journal of Chemistry

Pyrene dye has many superior characteristics for oxygen sensing studies such as long fluorescence lifetime, high quantum yield, and good sensitivity. It is preferred in some cases over ruthenium dyes for its more lipophilic character and higher sensitivity. However, easy photodegradation of pyrene is a challenging problem. In this study, pyrene dye was for the first time immobilized in an ethyl cellulose matrix and used for oxygen sensing in the form of thin films and electrospun sensing slides. The hydrophobic ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate was used as additive for the first time for dissolved oxygen sensing studies. The oxygen sensitivity …

Wavelength Dependent Specific Plasmon Resonance Coupling Of Single Silver Nanoparticles With Egfp, Kerry J. Lee, Tao Huang, Prakash D. Nallathamby

Chemistry & Biochemistry Faculty Publications

Noble metal nanoparticles (NPs) possess unique plasmonic properties, enabling them to serve as sub-diffraction light sources and nano-antennae for a wide range of applications. Here we report the specific interaction of single Ag NPs with single EGFP molecules and a high dependence of their interaction upon localized-surface-plasmon-resonance (LSPR) spectra of single Ag NPs and EGFP. The LSPR spectra of single red Ag NPs show a stunning 60 nm blue-shift during their incubation with EGFP, whereas they remain unchanged during their incubation with bovine serum albumin (BSA). Interestingly, the peak wavelengths of the LSPR spectra of green and blue Ag NPs …