Other search tools

About this data

The publication data currently available has been vetted by Vanderbilt faculty, staff, administrators and trainees. The data itself is retrieved directly from NCBI's PubMed and is automatically updated on a weekly basis to ensure accuracy and completeness.

If you have any questions or comments, please contact us.

Results: 1 to 10 of 20

Publication Record

Connections

Confirmation of disordered structure of ultrasmall CdSe nanoparticles from X-ray atomic pair distribution function analysis.
Yang X, Masadeh AS, McBride JR, Božin ES, Rosenthal SJ, Billinge SJ
(2013) Phys Chem Chem Phys 15: 8480-6
MeSH Terms: Cadmium Compounds, Molecular Structure, Nanoparticles, Powder Diffraction, Selenium Compounds
Show Abstract · Added May 27, 2014
The atomic pair distribution function (PDF) analysis of X-ray powder diffraction data has been used to study the structure of small and ultra-small CdSe nanoparticles. A method is described that uses a wurtzite and zinc-blende mixed phase model to account for stacking faults in CdSe particles. The mixed-phase model successfully describes the structure of nanoparticles larger than 2 nm yielding a stacking fault density of about 30%. However, for ultrasmall nanoparticles smaller than 2 nm, the models cannot fit the experimental PDF showing that the structure is significantly modified from that of larger particles and the bulk. The observation of a significant change in the average structure at ultra-small size is likely to explain the unusual properties of the ultrasmall particles such as their white light emitting ability.
0 Communities
1 Members
0 Resources
5 MeSH Terms
Determination of ebselen-sensitive reactive oxygen metabolites (ebROM) in human serum based upon N,N'-diethyl-1,4-phenylenediamine oxidation.
Liang Y, Roede JR, Dikalov S, Miller NG, Dudley SC, Quyyumi A, Jones DP
(2012) Clin Chim Acta 414: 1-6
MeSH Terms: Azoles, Humans, Molecular Structure, Organoselenium Compounds, Oxidation-Reduction, Oxidative Stress, Oxygen, Phenylenediamines
Show Abstract · Added February 17, 2016
BACKGROUND - Oxidative stress occurs through free radical- and non-radical-mediated oxidative mechanisms, but these are poorly discriminated by most assays. A convenient assay for oxidants in human serum is based upon the Fe(2+)-dependent decomposition of peroxides to oxidize N,N'-diethyl-1,4-phenylenediamine (DEPPD) to a stable radical cation which can be measured spectrophotometrically.
METHODS - We investigated modification of the DEPPD oxidation assay to discriminate color formation due to non-radical oxidants, including hydroperoxides and endoperoxides, which are sensitive to ebselen.
RESULTS - Use of serum, which has been pretreated with ebselen as a reference, provides a quantitative assay for non-radical, reactive oxidant species in serum, including hydroperoxides, endoperoxides and epoxides. In a set of 35 human serum samples, non-radical oxidants largely accounted for DEPPD oxidation in 86% of the samples while the remaining 14% had considerable contribution from other redox-active chemicals.
CONCLUSIONS - The simple modification in which ebselen-pretreated sample is used as a reference provides means to quantify non-radical oxidants in human serum. Application of this approach could enhance understanding of the contribution of different types of oxidative stress to disease.
Copyright © 2012 Elsevier B.V. All rights reserved.
0 Communities
1 Members
0 Resources
8 MeSH Terms
Dynamic fluctuations in ultrasmall nanocrystals induce white light emission.
Pennycook TJ, McBride JR, Rosenthal SJ, Pennycook SJ, Pantelides ST
(2012) Nano Lett 12: 3038-42
MeSH Terms: Cadmium Compounds, Color, Lighting, Materials Testing, Nanostructures, Particle Size, Selenium Compounds
Show Abstract · Added May 27, 2014
Individual ultrasmall CdSe nanocrystals have recently been found to emit white light, but the ultimate origin of the phenomenon has remained elusive. Here we use a combination of state-of-the-art experiment and theory to show that excitation sets the ultrasmall nanocrystals into a fluxional state. Their energy gaps vary continuously on a femtosecond time scale, so that even an individual nanocrystal can emit across the entire visual range. In addition, we observe the outer layers of the larger monochromatic emitting nanocrystals to be fluxional. Such fluxionality should be considered when optimizing nanocrystals for applications. Thus, small is indeed different, but ultrasmall is different yet again.
0 Communities
1 Members
0 Resources
7 MeSH Terms
Bright white light emission from ultrasmall cadmium selenide nanocrystals.
Rosson TE, Claiborne SM, McBride JR, Stratton BS, Rosenthal SJ
(2012) J Am Chem Soc 134: 8006-9
MeSH Terms: Cadmium Compounds, Color, Formates, Light, Nanoparticles, Particle Size, Selenium Compounds, Spectrum Analysis
Show Abstract · Added May 27, 2014
A simple treatment method using formic acid has been found to increase the fluorescence quantum yield of ultrasmall white light-emitting CdSe nanocrystals from 8% to 45%. Brighter white-light emission occurs with other carboxylic acids as well, and the magnitude of the quantum yield enhancement is shown to be dependent on the alkyl chain length. Additionally, the nanocrystal luminescence remains enhanced relative to the untreated nanocrystals over several days. This brightened emission opens the possibility for even further quantum yield improvement and potential for use of these white-light nanocrystals in solid-state lighting applications.
0 Communities
1 Members
0 Resources
8 MeSH Terms
Spectral modification and catalytic inhibition of human cytochromes P450 1A1, 1A2, 1B1, 2A6, and 2A13 by four chemopreventive organoselenium compounds.
Shimada T, Murayama N, Tanaka K, Takenaka S, Guengerich FP, Yamazaki H, Komori M
(2011) Chem Res Toxicol 24: 1327-37
MeSH Terms: Animals, Antineoplastic Agents, Aryl Hydrocarbon Hydroxylases, Binding Sites, Biocatalysis, Catalytic Domain, Computer Simulation, Cyanates, Cytochrome P-450 CYP1A1, Cytochrome P-450 CYP1A2, Cytochrome P-450 CYP1A2 Inhibitors, Cytochrome P-450 CYP1B1, Cytochrome P-450 CYP2A6, Cytochrome P-450 Enzyme Inhibitors, Cytochrome P-450 Enzyme System, Humans, Neoplasms, Organoselenium Compounds, Protein Binding, Rats
Show Abstract · Added March 26, 2014
Several organoselenium compounds including benzyl selenocyanate (BSC), 1,2-phenylenebis(methylene)selenocyanate (o-XSC), 1,3-phenylenebis(methylene)selenocyanate (m-XSC), and 1,4-phenylenebis(methylene)selenocyanate (p-XSC) have been shown to prevent cancers caused by polycyclic aromatic hydrocarbons (PAHs) and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) in experimental animals; these chemical carcinogens are activated by human P450 1 and 2A family enzymes, respectively, to carcinogenic metabolites. In this study, we examined whether these selenium compounds interact with and inhibit human P450 1 and 2A enzymes in vitro. Four organoselenium compounds induced reverse Type I binding spectra with P450 1A1, 1A2, and 1B1 and Type I binding spectra with P450 2A6 and 2A13. The spectral dissociation constants (K(s)) for the interaction of P450 1B1 with these chemicals were 3.6-5.7 μM; the values were lower than those with seen with P450 1A1 (19-30 μM) or 1A2 (6.3-13 μM). The K(s) values for Type I binding of P450 2A13 with m-XSC and BSC were both 0.20 μM; the values were very low compared to those for the interaction of P450 2A6 with m-XSC (5.7 μM) and BSC (2.0 μM). Four selenium compounds directly inhibited 7-ethoxyresorufin O-deethylation activities catalyzed by P450 1A1, 1A2, and 1B1 with IC(50) values <1.0 μM, except for the inhibition of P450 1A2 by BSC (1.3 μM). Coumarin 7-hydroxylation activities of P450 2A13 were more inhibited by four selenium compounds than those of P450 2A6, with IC(50) values of 0.22-1.4 μM for P450 2A13 and 2.4-6.2 μM for P450 2A6. Molecular docking studies of the interaction of four organoselenium compounds with human P450 enzymes suggest that these chemicals can be docked into the active sites of these human P450 enzymes and that the sites of the selenocyanate functional groups of these chemicals differ between the P450 1 and 2A family enzymes.
0 Communities
1 Members
0 Resources
20 MeSH Terms
Single-nanocrystal spectroscopy of white-light-emitting CdSe nanocrystals.
Dukes AD, Samson PC, Keene JD, Davis LM, Wikswo JP, Rosenthal SJ
(2011) J Phys Chem A 115: 4076-81
MeSH Terms: Cadmium Compounds, Nanostructures, Nanotechnology, Particle Size, Selenium Compounds, Spectrometry, Fluorescence, Surface Properties
Show Abstract · Added May 27, 2014
We report the observation of broad-spectrum fluorescence from single CdSe nanocrystals. Individual semiconductor nanocrystals typically have a narrower emission spectrum than that of an ensemble. However, our experiments show that the ensemble white-light emission observed in ultrasmall CdSe nanocrystals is the result of many single CdSe nanocrystals, each emitting over the entire visible spectrum. These results indicate that each white-light-emitting CdSe nanocrystal contains all the trap states that give rise to the observed white-light emission.
1 Communities
3 Members
0 Resources
7 MeSH Terms
GABAC receptor binding of quantum-dot conjugates of variable ligand valency.
Gussin HA, Tomlinson ID, Muni NJ, Little DM, Qian H, Rosenthal SJ, Pepperberg DR
(2010) Bioconjug Chem 21: 1455-64
MeSH Terms: Binding Sites, Cadmium Compounds, Fluorescence, Ligands, Methylamines, Molecular Structure, Muscimol, Polyethylene Glycols, Quantum Dots, Receptors, GABA, Selenium Compounds, Sulfides, Zinc Compounds
Show Abstract · Added May 27, 2014
Highly fluorescent CdSe quantum dots (qdots) can serve as a platform for tethering multiple copies of a receptor-targeted ligand, affording study of how the level of multivalency affects receptor binding. We previously showed that qdots conjugated with long PEG chains terminated by muscimol, a known GABA(C) agonist, exhibit specific binding to the surface membrane of GABA(C) receptor-expressing Xenopus oocytes. The present report addresses the effect of varying the number, i.e., valency, of muscimol- (M-) terminated PEG chains attached to the qdot on binding of the resulting conjugate to GABA(C) receptors. M-PEG-qdots of differing muscimol valency were prepared by conjugating AMP-CdSe/ZnS qdots with muscimol-terminated and methylamine-terminated PEG chains in proportions designed to yield varying percentages of muscimol-terminated chains among the total approximately 150-200 chains bound to the qdot. The investigated valencies represented 0%, approximately 25%, approximately 50%, and 100% loading with muscimol (preparations termed M-PEG-qdot0, M-PEG-qdot25, M-PEG-qdot50, and M-PEG-qdot100, respectively. Binding of a given conjugate to surface membranes of GABA(C) receptor-expressing oocytes was analyzed by quantitative fluorescence microscopy following defined incubation with approximately 30 nM of the conjugate. With 5-20 min incubation, the fluorescence signal resulting from incubation with M-PEG-qdot25 exceeded, by approximately 6-fold, the fluorescence level obtained with M-PEG-qdot preparations that lacked muscimol-terminated chains (M-PEG-qdot0). M-PEG-qdot50 yielded a net signal roughly similar to that of M-PEG-qdot25, and that produced by M-PEG-qdot100 exceeded, by approximately 30-50%, those for M-PEG-qdot25 and M-PEG-qdot50. The time course of changes in oocyte surface membrane fluorescence resulting from the introduction of and removal of M-PEG-qdots in the medium bathing the oocyte indicated only a modest dependence of both binding and wash-out kinetics on muscimol valency. The results demonstrate a dependence of the binding activity of the M-PEG-qdot conjugates on muscimol valency, presumably reflecting higher GABA(C) avidity and/or affinity of the muscimol at high valency, and provide insight on the interactions of membrane receptor proteins with qdot conjugates containing multiple copies of a receptor-targeting ligand.
0 Communities
1 Members
0 Resources
13 MeSH Terms
White light-emitting diodes based on ultrasmall CdSe nanocrystal electroluminescence.
Schreuder MA, Xiao K, Ivanov IN, Weiss SM, Rosenthal SJ
(2010) Nano Lett 10: 573-6
MeSH Terms: Cadmium Compounds, Crystallization, Electrochemistry, Equipment Design, Light, Luminescence, Nanoparticles, Nanotechnology, Selenium Compounds, Temperature
Show Abstract · Added May 27, 2014
We report white light-emitting diodes fabricated with ultrasmall CdSe nanocrystals, which demonstrate electroluminescence from a size of nanocrystals (<2 nm) previously thought to be unattainable. These LEDs have excellent color characteristics, defined by their pure white CIE color coordinates (0.333, 0.333), correlated color temperatures of 5461-6007 K, and color rendering indexes as high as 96.6. The effect of high voltage on the trap states responsible for the white emission is also described.
0 Communities
2 Members
0 Resources
10 MeSH Terms
Selenium modification of nucleic acids: preparation of phosphoroselenoate derivatives for crystallographic phasing of nucleic acid structures.
Pallan PS, Egli M
(2007) Nat Protoc 2: 640-6
MeSH Terms: Chromatography, High Pressure Liquid, Crystallography, Molecular Structure, Nucleic Acids, Phosphorus Compounds, Selenium, Selenium Compounds
Show Abstract · Added March 5, 2014
This protocol describes a simplified means of introducing an anomalously scattering atom into oligonucleotides by conventional solid-phase synthesis. Replacement of a nonbridging phosphate oxygen in the backbone with selenium is practically suitable for any nucleic acid. The resulting oligonucleotide P-diastereomers can be separated using anion exchange HPLC to yield diastereomerically pure phosphoroselenoates (PSes). The total time for the synthesis and ion-exchange HPLC separation of pure PSe is approximately 60 h.
0 Communities
1 Members
0 Resources
7 MeSH Terms
Binding of muscimol-conjugated quantum dots to GABAC receptors.
Gussin HA, Tomlinson ID, Little DM, Warnement MR, Qian H, Rosenthal SJ, Pepperberg DR
(2006) J Am Chem Soc 128: 15701-13
MeSH Terms: Animals, Binding Sites, Cadmium Compounds, Cells, Cultured, Coated Materials, Biocompatible, Fluorescent Dyes, GABA Agonists, Gene Expression Regulation, Models, Chemical, Muscimol, Nanoparticles, Oocytes, Polyethylene Glycols, Quantum Dots, Receptors, Cell Surface, Receptors, GABA, Selenium Compounds, Spectrometry, Fluorescence, Sulfides, Zinc Compounds
Show Abstract · Added May 27, 2014
Functionalization of highly fluorescent CdSe/ZnS core-shell nanocrystals (quantum dots, qdots) is an emerging technology for labeling cell surface proteins. We have synthesized a conjugate consisting of approximately 150-200 muscimols (a GABA receptor agonist) covalently joined to the qdot via a poly(ethylene glycol) (PEG) linker (approximately 78 ethylene glycol units) and investigated the binding of this muscimol-PEG-qdot conjugate to homomeric rho1 GABAC receptors expressed in Xenopus oocytes. GABAC receptors mediate inhibitory synaptic signaling at multiple locations in the central nervous system (CNS). Binding of the conjugate was analyzed quantitatively by determining the fluorescence intensity of the oocyte surface membrane in relation to that of the surrounding incubation medium. Upon 5- to 10-min incubation with muscimol-PEG-qdots (34 nM in qdot concentration), GABAC-expressing oocytes exhibited a fluorescent halo at the surface membrane that significantly exceeded the fluorescence of the incubation medium. This halo was absent following muscimol-PEG-qdot treatment of oocytes lacking GABAC receptors. Incubation of the oocyte with free muscimol (100 microM-5 mM), PEG-muscimol (500 microM), or GABA (100 microM - 5 mM) substantially reduced or eliminated the fluorescence halo produced by muscimol-PEG-qdots, and the removal of GABA or free muscimol led to a recovery of muscimol-PEG-qdot binding. Unconjugated qdots and PEG-qdots that lacked conjugated muscimol neither exhibited significant binding activity nor diminished the subsequent binding of muscimol-PEG-qdots. The results indicate that muscimol joined to qdots via a long-chain PEG linker exhibits specific binding activity at the ligand-binding pocket of expressed GABAC receptors, despite the presence of both the long PEG linker and the sterically bulky qdot.
0 Communities
1 Members
0 Resources
20 MeSH Terms