scholarly journals Development of c-type lectin oriented surfaces for high avidity glycoconjugates: towards mimicking multivalent interactions on the cell surface

2019 ◽  
Author(s):  
Vanessa Porkolab ◽  
Carlo Pifferi ◽  
Ieva Sutkeviciute ◽  
Stefania Ordanini ◽  
Marwa Taouai ◽  
...  
Keyword(s):  
Active Sites ◽  
Direct Interaction ◽  
High Avidity ◽  
Binding Properties ◽  
Binding Partner ◽  
Full Characterization ◽  
Wide Range ◽  
Multivalent Interactions ◽  
Binding Mechanisms

ABSTRACTMultivalent interactions between complex carbohydrates and oligomeric C-type lectins govern a wide range of immune responses. Up to date, standard SPR (surface plasmon resonance) competitive assays have largely been to evaluate binding properties from monosaccharide units (low affinity, mM) to multivalent elemental antagonists (moderate affinity, µM). Herein, we report typical case-studies of SPR competitive assays showing that they underestimate the potency of glycoclusters to inhibit the interaction between DC-SIGN and immobilized glycoconjugates. This paper describes the design and implementation of a SPR direct interaction over DC-SIGN oriented surfaces, extendable to other C-type lectin surfaces as such Langerin. This setup provides a microscopic overview of intrinsic avidity generation emanating simultaneously from multivalent glycoclusters and from DC-SIGN tetramers that are organized in nanoclusters on the cell membrane. For this purpose, covalent biospecific capture of DC-SIGN via StreptagII /StrepTactin interaction offers the preservation of tetrameric DC-SIGN and the accessibility/functionality of all active sites. From the tested glycoclusters libraries, we demonstrated that the scaffold architecture, the valency and the glycomimetic-based ligand are crucial to reach nanomolar affinities for DC-SIGN. The glycocluster 3.D illustrates the tightest binding partner in this set for a DC-SIGN surface (Kd= 18 nM). Moreover, the selectivity at monovalent scale of glycomimetic D can be easily analyzed at multivalent scale comparing its binding over different C-type lectin immobilized surfaces. This approach may give rise to novel insights into the multivalent binding mechanisms responsible to avidity and make a major contribution to the full characterization of the binding potency of promising specific and multivalent immunomodulators.

Design and Synthesis of High-Avidity Tetravalent Glycoclusters as Probes for Sambucus sieboldiana Agglutinin and Characterization of their Binding Properties

2012 ◽  
Vol 23 (1) ◽  
pp. 97-105 ◽  
Author(s):  
Makoto Ogata ◽  
Megumi Yano ◽  
Seiichiro Umemura ◽  
Takeomi Murata ◽  
Enoch Y. Park ◽  
...  
Keyword(s):  
High Avidity ◽  
Binding Properties ◽  
Design And Synthesis

scholarly journals Characterization and Structure Elucidation of Binary Zr:Ti MEL Structure; Simultaneous Photodegradation/Removal of Organic–Inorganic Pollutants

Catalysts ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 633
Author(s):  
Samia A. Kosa ◽  
Islam H. Abd El Maksod ◽  
Eman Z. Hegazy ◽  
Naha M. Al-sebaii
Keyword(s):  
Crystalline Phase ◽  
Active Site ◽  
Structure Elucidation ◽  
Active Sites ◽  
Mutual Effect ◽  
Blue Dye ◽  
Inorganic Pollutants ◽  
Full Characterization ◽  
Cobalt And Nickel

The preparation of a series of different Ti/Zr MEL structure was performed successfully. Full characterization of the prepared materials was done using XRD, IR, DR, and SEM. The results show that the prepared materials contain only one crystalline phase (ZSM-11). The affinity of Zr to form the crystalline phase alone in a binary Zr/Ti synthesizing mixture was approved by SEM and elemental analysis results. The percentage of each active site was calculated. DR spectra were deconvoluted, and three active sites were supposed and quantified (tetragonal, octahedral, and crystalline). The mutual effect of ions (lead, copper, cobalt, and nickel) and methylene blue dye on the removal efficiency with and without ultraviolet irradiation was examined and fully characterized. The ions largely influence the photodegradation process, and a mechanism was formulated. Meanwhile, the presence of dye showed a negligible effect on the removal of ions.

scholarly journals Synthesis, Characterization and Biological Activates Studies of some New Derivatives From 2-aminoo-5-mercapto-1, 3, 4-thiadiazole

2018 ◽  
Vol 15 (1) ◽  
pp. 48-56
Author(s):  
Baghdad Science Journal
Keyword(s):  
Active Sites ◽  
Acetyl Chloride ◽  
Azo Compounds ◽  
Thiazole Ring ◽  
Diazonium Salts ◽  
Material Base ◽  
Anhydrous Sodium Carbonate ◽  
Full Characterization ◽  
Ft Ir

In this work, thiadiazole derivatives were prepared by taking advantage of active sites in (2-amino-5-mercapto-1, 3, 4-thiadiazole) as a starting material base. The main heterocyclic compounds (1, 3, 4-thiadiazole, oxazole) etc, 2-amino-5-mercapto-1,3,4-thiadiazole compound (1) was prepared by cyclic closure of thiosemicarbazide compound with anhydrous sodium carbonate and carbon disulfide. Oxidation of (1) via hydrogen peroxide, to have (2) which was treated with chloro acetyl chloride to get (3). Preparation of thiazole ring (4) was from reacting of (3) with thiourea. Synthesis of diazonium salts (5) from compound (4) using sodium nitrite and HCl. Compound (5) reacted with different ester compounds to prepare a new azo compounds (6–8).Compound (3) reacts with viruses secondary amine to prepare compound (9–11). Full characterization of the synthesized compounds was done by using spectroscopic analysis such as FT-IR, 1H-NMR and C.H.N.S. technique.

Study of the Radiation Damage Induced by High Energy Gamma-Ray in CdTe Detectors

1997 ◽  
Vol 487 ◽  
Author(s):  
P. Chirco ◽  
M. Zanarini ◽  
E. Querzola ◽  
G. Zambelli ◽  
W. Dusi ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Deep Level ◽  
High Energy ◽  
Semiconductor Detectors ◽  
Dose Rates ◽  
Full Characterization ◽  
Wide Range ◽  
Energy Gamma ◽  
Transient Spectroscopy

AbstractIn recent years the performance of room-temperature semiconductor detectors such as CdTe are improved and they are now suitable candidates for several applications. However, some key parameters that can severely affect such perfomances have not been measured yet. Thus we have studied the damaging of a set of CdTe detectors irradiated in a 60Co gamma-cell in a wide range of doses and dose-rates. A full characterization of the performance of irradiated detectors has been obtained by means of spectroscopic, electrostatic, photo-induced current transient spectroscopy and photo-deep level transient spectroscopy measurements to quote the energy resolution, the leakage current, the activation energy and capture cross-section of deep level defects, respectively.

Modeling Grain Boundary Scattering in Nanocomposites

2008 ◽  
Author(s):  
Austin Minnich ◽  
Daryoosh Vashaee ◽  
Gang Chen
Keyword(s):  
Grain Boundary ◽  
Thermoelectric Properties ◽  
Boundary Scattering ◽  
Full Characterization ◽  
Scattering Rate ◽  
Relaxation Time Approximation ◽  
Grain Boundary Scattering ◽  
Wide Range ◽  
Bulk Data

Modeling the thermoelectric properties of nanocomposites is difficult due to the complex grain boundary scattering processes which scatter both electrons and phonons. In this work we introduce several models which characterize the grain boundary scattering rate. This scattering rate is incorporated into a code we developed which numerically calculates the electrical and thermal properties of bulk and nanocomposite thermoelectric materials using the Boltzmann equation under the relaxation time approximation. The code is capable of calculating all the relevant thermoelectric properties over a wide range of temperatures, doping concentrations, and compositions, allowing for a full characterization of the material. We formulate two grain boundary scattering rates and implement the commonly used Mayadas model. The code and all of the grain boundary scattering models are then validated on bulk data for SiGe and applied to nano-SiGe. All the models are able to fit the experimental data after a fitting parameter is suitably chosen, so we determine which model is most appropriate based on the physical assumptions made by each model.

Modeling the Thermoelectric Properties of Nanocomposites

2008 ◽  
Author(s):  
Austin Minnich ◽  
Gang Chen
Keyword(s):  
Grain Boundary ◽  
Thermoelectric Properties ◽  
Thermoelectric Materials ◽  
Boundary Scattering ◽  
Full Characterization ◽  
Scattering Rate ◽  
Relaxation Time Approximation ◽  
Grain Boundary Scattering ◽  
Wide Range

Modeling the thermoelectric properties of nanocomposites is difficult due to the complex grain boundary scattering processes which scatter both electrons and phonons. In this work we describe a code we developed which numerically calculates the electrical and thermal properties of bulk and nanocomposite thermoelectric materials using the Boltzmann equation under the relaxation time approximation. The code is capable of calculating all the relevant thermoelectric properties over a wide range of temperatures, doping concentrations, and compositions, allowing for a full characterization of the material. We model nanocomposites by incorporating a grain boundary scattering rate based on a simple model we developed and models in the literature. The code and grain boundary scattering models are validated on bulk data and data from nano-SiGe, and are then applied to other candidate thermoelectric materials to see if they would be good candidates for nanocomposites. The analysis shows that GaAs might be promising as a nanocomposite thermoelectric material.

Intrinsic Stacking Interactions of Natural and Artificial Nucleobases

2019 ◽  
Author(s):  
Drew P. Harding ◽  
Laura J. Kingsley ◽  
Glen Spraggon ◽  
Steven Wheeler
Keyword(s):  
Gas Phase ◽  
Electrostatic Interactions ◽  
Density Functional ◽  
Molecular Descriptors ◽  
Stacking Interactions ◽  
Interaction Energies ◽  
Functional Theory ◽  
Binding Partner ◽  
Heavy Atoms ◽  
Wide Range

The intrinsic (gas-phase) stacking energies of natural and artificial nucleobases were explored using density functional theory (DFT) and correlated ab initio methods. Ranking the stacking strength of natural nucleobase dimers revealed a preference in binding partner similar to that seen from experiments, namely G > C > A > T > U. Decomposition of these interaction energies using symmetry-adapted perturbation theory (SAPT) showed that these dispersion dominated interactions are modulated by electrostatics. Artificial nucleobases showed a similar stacking preference for natural nucleobases and were also modulated by electrostatic interactions. A robust predictive multivariate model was developed that quantitively predicts the maximum stacking interaction between natural and a wide range of artificial nucleobases using molecular descriptors based on computed electrostatic potentials (ESPs) and the number of heavy atoms. This model should find utility in designing artificial nucleobase analogs that exhibit stacking interactions comparable to those of natural nucleobases. Further analysis of the descriptors in this model unveil the origin of superior stacking abilities of certain nucleobases, including cytosine and guanine.

A Pyridinic Fe-N4 Macrocycle Effectively Models the Active Sites in Fe/N-Doped Carbon Electrocatalysts

2020 ◽  
Author(s):  
Travis Marshall-Roth ◽  
Nicole J. Libretto ◽  
Alexandra T. Wrobel ◽  
Kevin Anderton ◽  
Nathan D. Ricke ◽  
...  
Keyword(s):  
Oxygen Reduction ◽  
Active Sites ◽  
Catalytic Properties ◽  
Reduction Reaction ◽  
Iron Phthalocyanine ◽  
Electrochemical Studies ◽  
Onset Potential ◽  
Nitrogen Doped Carbon ◽  
Iron Active Sites

Iron- and nitrogen-doped carbon (Fe-N-C) materials are leading candidates to replace platinum in fuel cells, but their active site structures are poorly understood. A leading postulate is that iron active sites in this class of materials exist in an Fe-N<sub>4</sub> pyridinic ligation environment. Yet, molecular Fe-based catalysts for the oxygen reduction reaction (ORR) generally feature pyrrolic coordination and pyridinic Fe-N<sub>4</sub> catalysts are, to the best of our knowledge, non-existent. We report the synthesis and characterization of a molecular pyridinic hexaazacyclophane macrocycle, (phen<sub>2</sub>N<sub>2</sub>)Fe, and compare its spectroscopic, electrochemical, and catalytic properties for oxygen reduction to a prototypical Fe-N-C material, as well as iron phthalocyanine, (Pc)Fe, and iron octaethylporphyrin, (OEP)Fe, prototypical pyrrolic iron macrocycles. N 1s XPS signatures for coordinated N atoms in (phen<sub>2</sub>N<sub>2</sub>)Fe are positively shifted relative to (Pc)Fe and (OEP)Fe, and overlay with those of Fe-N-C. Likewise, spectroscopic XAS signatures of (phen<sub>2</sub>N<sub>2</sub>)Fe are distinct from those of both (Pc)Fe and (OEP)Fe, and are remarkably similar to those of Fe-N-C with compressed Fe–N bond lengths of 1.97 Å in (phen<sub>2</sub>N<sub>2</sub>)Fe that are close to the average 1.94 Å length in Fe-N-C. Electrochemical studies establish that both (Pc)Fe and (phen<sub>2</sub>N<sub>2</sub>)Fe have relatively high Fe(III/II) potentials at ~0.6 V, ~300 mV positive of (OEP)Fe. The ORR onset potential is found to directly correlate with the Fe(III/II) potential leading to a ~300 mV positive shift in the onset of ORR for (Pc)Fe and (phen<sub>2</sub>N<sub>2</sub>)Fe relative to (OEP)Fe. Consequently, the ORR onset for (phen<sub>2</sub>N<sub>2</sub>)Fe and (Pc)Fe is within 150 mV of Fe-N-C. Unlike (OEP)Fe and (Pc)Fe, (phen<sub>2</sub>N<sub>2</sub>)Fe displays excellent selectivity for 4-electron ORR with <4% maximum H<sub>2</sub>O<sub>2</sub> production, comparable to Fe-N-C materials. The aggregate spectroscopic and electrochemical data establish (phen<sub>2</sub>N<sub>2</sub>)Fe as a pyridinic iron macrocycle that effectively models Fe-N-C active sites, thereby providing a rich molecular platform for understanding this important class of catalytic materials.<p><b></b></p>

A Thorough Theoretical Exploration of Intriguing Characteristics of Cyclo[18]carbon: Geometry, Bonding Nature, Aromaticity, Weak Interaction, Reactivity, Excited States, Vibrations, Molecular Dynamics and Various Molecular Properties

2019 ◽  
Author(s):  
Tian Lu ◽  
Qinxue Chen ◽  
Zeyu Liu
Keyword(s):  
Molecular Dynamics ◽  
Excited States ◽  
Electronic Excitation ◽  
Ring Structure ◽  
Molecular Properties ◽  
Molecular Vibration ◽  
Full Characterization ◽  
Long Time ◽  
Almost All

Although cyclo[18]carbon has been theoretically and experimentally investigated since long time ago, only very recently it was prepared and directly observed by means of STM/AFM in condensed phase (Kaiser et al., <i>Science</i>, <b>365</b>, 1299 (2019)). The unique ring structure and dual 18-center π delocalization feature bring a variety of unusual characteristics and properties to the cyclo[18]carbon, which are quite worth to be explored. In this work, we present an extremely comprehensive and detailed investigation on almost all aspects of the cyclo[18]carbon, including (1) Geometric characteristics (2) Bonding nature (3) Electron delocalization and aromaticity (4) Intermolecular interaction (5) Reactivity (6) Electronic excitation and UV/Vis spectrum (7) Molecular vibration and IR/Raman spectrum (8) Molecular dynamics (9) Response to external field (10) Electron ionization, affinity and accompanied process (11) Various molecular properties. We believe that our full characterization of the cyclo[18]carbon will greatly deepen researchers' understanding of this system, and thereby help them to utilize it in practice and design its various valuable derivatives.

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