scholarly journals A Sustainable Biomineralization Approach for the Synthesis of Highly Fluorescent Ultra-Small Pt Nanoclusters

Biosensors ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 128 ◽  
Author(s):  
Rajkamal Balu ◽  
Robert Knott ◽  
Christopher M. Elvin ◽  
Anita J. Hill ◽  
Namita R. Choudhury ◽  
...  
Keyword(s):  
Quantum Yield ◽  
Photoelectron Spectroscopy ◽  
Photophysical Properties ◽  
Conformational Dynamics ◽  
Aqueous Media ◽  
Intrinsically Disordered Protein ◽  
X Ray ◽  
Pt Nanoclusters ◽  
Intrinsically Disordered ◽  
Green Fluorescent

Herein we report the first example of a facile biomineralization process to produce ultra-small-sized highly fluorescent aqueous dispersions of platinum noble metal quantum clusters (Pt-NMQCs) using a multi-stimulus responsive, biomimetic intrinsically disordered protein (IDP), Rec1-resilin. We demonstrate that Rec1-resilin acts concurrently as the host, reducing agent, and stabilizer of the blue-green fluorescent Pt-NMQCs once they are being formed. The photophysical properties, quantum yield, and fluorescence lifetime measurements of the synthesized Pt-NMQCs were examined using UV-Vis and fluorescence spectroscopy. The oxidation state of the Pt-NMQCs was quantitatively analyzed using X-ray photoelectron spectroscopy. Both a small angle X-ray scattering technique and a modeling approach have been attempted to present a detailed understanding of the structure and conformational dynamics of Rec1-resilin as an IDP during the formation of the Pt-NMQCs. It has been demonstrated that the green fluorescent Pt-NMQCs exhibit a high quantum yield of ~7.0% and a lifetime of ~9.5 ns in aqueous media. The change in photoluminescence properties due to the inter-dot interactions between proximal dots and aggregation of the Pt-NMQCs by evaporation was also measured spectroscopically and discussed.

scholarly journals X-ray structure of the PHF core C-terminus: Insight into the folding of the intrinsically disordered protein tau in Alzheimer's disease

FEBS Letters ◽  
2007 ◽  
Vol 581 (30) ◽  
pp. 5872-5878 ◽  
Author(s):  
Jozef Sevcik ◽  
Rostislav Skrabana ◽  
Radovan Dvorsky ◽  
Natalia Csokova ◽  
Khalid Iqbal ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Intrinsically Disordered Protein ◽  
X Ray ◽  
Protein Tau ◽  
Intrinsically Disordered ◽  
Disordered Protein ◽  
C Terminus ◽  
Insight Into

scholarly journals NSP 11 of SARS-CoV-2 is an Intrinsically Disordered Protein

2020 ◽  
Author(s):  
Kundlik Gadhave ◽  
Prateek Kumar ◽  
Ankur Kumar ◽  
Taniya Bhardwaj ◽  
Neha Garg ◽  
...  
Keyword(s):  
Amino Acid ◽  
Intrinsically Disordered Proteins ◽  
Conformational Dynamics ◽  
Alpha Helix ◽  
Intrinsically Disordered Protein ◽  
Disordered Proteins ◽  
Helical Conformation ◽  
Structural Protein ◽  
Intrinsically Disordered ◽  
Protein Size

AbstractThe intrinsically disordered proteins/regions (IDPs/IDPRs) are known to be responsible for multiple cellular processes and are associated with many chronic diseases. In viruses, the existence of disordered proteome is also proven and are related with its conformational dynamics inside the host. The SARS-CoV-2 virus has a large proteome, in which, structure and functions of many proteins are not known as of yet. Previously, we have investigated the dark proteome of SARS-CoV-2. However, the disorder status of non-structural protein 11 (nsp11) was not possible because of very small in size, just 13 amino acid long, and for most of the IDP predictors, the protein size should be at least 30 amino acid long. Also, the structural dynamics and function status of nsp11 was not known. Hence, we have performed extensive experimentation on nsp11. Our results, based on the Circular dichroism spectroscopy gives characteristic disordered spectrum for IDPs. Further, we investigated the conformational behaviour of nsp11 in the presence of membrane mimetic environment, alpha helix inducer, and natural osmolyte. In the presence of negatively charged and neutral liposomes, nsp11 remains disordered. However, with SDS micelle, it adopted an α-helical conformation, suggesting the helical propensity of nsp11. At the end, we again confirmed the IDP behaviour of nsp11 using molecular dynamics simulations.

Novel Cyclometalated Iridium(III) Xanthate Complexes and Their Phosphorescence Behavior in the Presence of Metal Ions

2012 ◽  
Vol 67 (9) ◽  
pp. 865-871
Author(s):  
Bihai Tong ◽  
Yaqing Xu ◽  
Jiayan Qiang ◽  
Man Zhang ◽  
Qunbo Mei ◽  
...  
Keyword(s):  
Quantum Yield ◽  
Metal Ions ◽  
Single Crystal ◽  
Photophysical Properties ◽  
Metal Cations ◽  
X Ray Diffraction ◽  
Red Emission ◽  
X Ray ◽  
Emission Lifetime ◽  
Phosphorescence Quantum Yield

Two cyclometalated iridium(III) complexes, Ir(dpppz)(ppz)(ipx) and Ir(ppz)2(ipx) (dpppzH=1- (2,6-dimethylphenoxy)-4-phenylphthalazine, ppzH=4-phenylphthalazinone, ipx=isopropyl xanthate), have been synthesized and characterized by single-crystal X-ray diffraction. The photophysical properties of the two complexes were also investigated. Ir(dpppz)(ppz)(ipx) shows orange-red emission at around 606 nm with a phosphorescence quantum yield of ca. 0.0032 and an emission lifetime of 188 ns, while Ir(ppz)2(ipx) shows orange-red emission at around 599 nm with a phosphorescence quantum yield of ca. 0.00318 and an emission lifetime of 259 ns. The phosphorescence behavior of Ir(ppz)2(ipx) towards different metal cations has also be studied. Its strong phosphorescence is quenched by Hg2+, Cu2+ and Ag+ cations. The interaction ratio with Hg2+ is 1:1

scholarly journals Analysis of Protein Disorder Predictions in the Light of a Protein Structural Alphabet

Biomolecules ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 1080 ◽  
Author(s):  
Alexandre G. de Brevern
Keyword(s):  
Intrinsically Disordered Protein ◽  
Sequence Structure ◽  
Structural Alphabet ◽  
X Ray ◽  
Intrinsically Disordered ◽  
Disordered Protein ◽  
New Ideas ◽  
Local Conformations ◽  
Continuum Of States ◽  
Disease Pathways

Intrinsically-disordered protein (IDP) characterization was an amazing change of paradigm in our classical sequence-structure-function theory. Moreover, IDPs are over-represented in major disease pathways and are now often targeted using small molecules for therapeutic purposes. This has had created a complex continuum from order-that encompasses rigid and flexible regions-to disorder regions; the latter being not accessible through classical crystallographic methodologies. In X-ray structures, the notion of order is dictated by access to resolved atom positions, providing rigidity and flexibility information with low and high experimental B-factors, while disorder is associated with the missing (non-resolved) residues. Nonetheless, some rigid regions can be found in disorder regions. Using ensembles of IDPs, their local conformations were analyzed in the light of a structural alphabet. An entropy index derived from this structural alphabet allowed us to propose a continuum of states from rigidity to flexibility and finally disorder. In this study, the analysis was extended to comparing these results to disorder predictions, underlying a limited correlation, and so opening new ideas to characterize and predict disorder.

Colloidal Synthesis and Properties of InAs/InP and InAs/CdSe Core/Shell Nanocrystals

1999 ◽  
Vol 571 ◽  
Author(s):  
Yun-Wei Cao ◽  
Julia Aksenton ◽  
Victor Soloviev ◽  
Uri Banin
Keyword(s):  
Quantum Dots ◽  
Quantum Yield ◽  
Photoelectron Spectroscopy ◽  
Shell Growth ◽  
Band Gap Energy ◽  
Colloidal Synthesis ◽  
Core Shell ◽  
Cdse Core ◽  
X Ray ◽  
Photoluminescence Quantum Yield

ABSTRACTHigh-temperature colloidal synthesis of InAs/InP and InAs/CdSe core/shell nanocrystal quantum dots is reported. InP and CdSe shells with several thicknesses were grown on InAs cores ranging in diameter between 20 to 50 Å. Optical spectra, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and X-ray diffraction (XRD) were used to analyze the core/shell quantum dots and determine their chemical composition, average size, size distributions, and structures. The experimental results indicate that shell growth is uniform, expitaxial, and controllable. For both InP and CdSe shells, growth is accompanied by a red shift of the band gap energy as a result of the extension of the electron wavefunction into the shell region. An increase of the room temperature photoluminescence quantum yield by a factor of∼4 is observed with CdSe shell growth on InAs Cores. The growth of InP shells, however, quenches the photoluminescence quantum yield. The difference is assigned to outer surface effects in core/shell nanocrystals.

Activation of Peroxymonosulfate by CuNi@C Derived from Metal–Organic Frameworks Precursor

2018 ◽  
Vol 71 (11) ◽  
pp. 874 ◽  
Author(s):  
Xue Huang ◽  
Jing Zhang ◽  
Xiao Zhang ◽  
Qing-Ping Wu ◽  
Chun-Hui Yan
Keyword(s):  
Photoelectron Spectroscopy ◽  
Metallic Copper ◽  
Metal Organic Frameworks ◽  
Aqueous Media ◽  
Oxidative Degradation ◽  
Acid Orange 7 ◽  
X Ray Diffraction ◽  
X Ray ◽  
Initial Ph ◽  
Metal Organic

Calcined Cu-based metal–organic frameworks impregnated with nickel nitrate catalysts (CuNi@C) were synthesised. X-Ray diffraction, scanning electronic microscopy, energy dispersive X-ray spectrometry, and X-ray photoelectron spectroscopy techniques were applied for the characterisation of the synthesised catalyst, which revealed an octahedral particle shape, rough surface, and metallic copper (Cu, CuO) and nickel (Ni, NiO) particles. CuNi@C was fabricated as a novel peroxymonosulfate (PMS) activator for the oxidative degradation of Acid Orange 7 (AO7) in aqueous media. Results showed that the CuNi@C/PMS system can efficiently degrade nearly 100 % of 0.02 mmol L−1 AO7 within 60 min. In addition, the trapping experiments confirmed the participation of sulfate radicals (SO4•−) and hydroxyl radicals (HO•) as reactive species in the system. Furthermore, the effects of parameters including catalyst and PMS dosages, initial concentration of AO7, and pH were studied. Results showed that the decolourisation efficiency increased with the increase of catalyst dosage, but decreased with the increase of AO7 concentration. The optimal PMS concentration was 0.675 mmol L−1, and initial pH showed no significant effect on the degradation of AO7. Moreover, the CuNi@C could be reused four times with good activity and reusability. Findings revealed that the CuNi@C/PMS system shows potential for degrading contaminants in the environment, due to its catalytic activity and non-negligible adsorption.

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