Quantum mechanical ab initio calculations of the structural,electronic and optical properties of bulk gold nitrides

In the present work, the atomic and the electronic structures of Au₃N, AuN and AuN₂ are investigated using first-principles density-functional theory (DFT). We studied cohesive energy vs. volume data for a wide range of possible structures of these nitrides. Obtained data were fitted to a Birch-Murnaghan third-order equation of state (EOS) so as to identify the most likely candidates for the true crystal structure in this subset of the infinite parameter space, and to determine their equilibrium structural parameters. The analysis of the electronic properties was achieved by the calculations of the band structure and the total and partial density of states (DOS). Some possible pressure-induced structural phase transitions have been pointed out. Further, we carried out GW₀ calculations within the random-phase approximation (RPA) to the dielectric tensor to investigate the optical spectra of the experimentally suggested modification: Au₃N(D0₉). Obtained results are compared with experiment and with some available previous calculations.     

Gradual Growth of Gold Nanoseeds on Silica for Silica@Gold Core–Shell Nano Applications by Two Different Methods: A Comparison on Structural Properties

This paper describes the homogeneous growth of gold shells on the surfaces of spherical dielectric silica nanoparticle cores by two different approaches: common two-step method (the name) and deposition–precipitation process. The methods basically are different in forming the precursor gold seed particles on silica. The structural and optical properties and morphology of the nanoparticles were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), UV–Vis spectrophotometery, and photo luminescence spectroscopy (PL). The results showed that, although in both the methods the core–shell nanoparticles can be reliably prepared in a controlled fashion with a favorable uniformity, but deposition–precipitation method indicated a better mechanical stability while it was more cost and time effective too. A regular red shift, from 488 to 662 nm, and peak broadening was also risen for the striking plasmon absorption peak as gold nanoseeds created by each of the two methods grew in size on silica cores.     

Ultrasensitive,Rapid, and Selective Detection of Mercury Using Graphene Assisted Laser Desorption/Ionization Mass Spectrometry

We report an extremely sensitive and specific detection of mercuric ions (Hg²⁺) based on graphene assisted laser desorption/ionization mass spectrometry (GALDI-MS). Combining the highly selective coordination interactions between thymine (T) and Hg²⁺, we present a simple, effective, and novel approach, based on π–π interactions of the T-Hg²⁺-T complex and G that can serve as a platform and matrix for GALDI-MS. The present sensor not only exhibits high selectivity and sensitivity (picomolar) to Hg²⁺ in aqueous solution, but also can elucidate the chemical structures of the metal complexes. The significant advantage in the current approach is that there is no need for a sophisticated instrument, and no sample pretreatment is required to detect the Hg²⁺ ions.

An efficient and novel protocol for the synthesis of spiro[1,3]oxazino[5,6-c]quinoline derivatives by one-pot,three-component reaction

Research on Chemical Intermediates - One-pot, three-component reaction of various aryl glyoxal monohydrates, 5-methylisoxazol-3-amine and 4-hydroxyquinolin-2(1H)-one in the presence of a catalytic...     

Deciphering the Role of Filamin B Calponin-Homology Domain in Causing the Larsen Syndrome,Boomerang Dysplasia,and Atelosteogenesis Type I Spectrum Disorders via a Computational Approach

Filamins (FLN) are a family of actin-binding proteins involved in regulating the cytoskeleton and signaling phenomenon by developing a network with F-actin and FLN-binding partners. The FLN family comprises three conserved isoforms in mammals: FLNA, FLNB, and FLNC. FLNB is a multidomain monomer protein with domains containing an actin-binding N-terminal domain (ABD 1–242), encompassing two calponin-homology domains (assigned CH1 and CH2). Primary variants in FLNB mostly occur in the domain (CH2) and surrounding the hinge-1 region. The four autosomal dominant disorders that are associated with FLNB variants are Larsen syndrome, atelosteogenesis type I (AOI), atelosteogenesis type III (AOIII), and boomerang dysplasia (BD). Despite the intense clustering of FLNB variants contributing to the LS-AO-BD disorders, the genotype-phenotype correlation is still enigmatic. In silico prediction tools and molecular dynamics simulation (MDS) approaches have offered the potential for variant classification and pathogenicity predictions. We retrieved 285 FLNB missense variants from the UniProt, ClinVar, and HGMD databases in the current study. Of these, five and 39 variants were located in the CH1 and CH2 domains, respectively. These variants were subjected to various pathogenicity and stability prediction tools, evolutionary and conservation analyses, and biophysical and physicochemical properties analyses. Molecular dynamics simulation (MDS) was performed on the three candidate variants in the CH2 domain (W148R, F161C, and L171R) that were predicted to be the most pathogenic. The MDS analysis results showed that these three variants are highly compact compared to the native protein, suggesting that they could affect the protein on the structural and functional levels. The computational approach demonstrates the differences between the FLNB mutants and the wild type in a structural and functional context. Our findings expand our knowledge on the genotype-phenotype correlation in FLNB-related LS-AO-BD disorders on the molecular level, which may pave the way for optimizing drug therapy by integrating precision medicine.     

Voltammetric Label‐free Immunosensors for the Diagnosis of Cystic Echinococcosis

Cystic echinococcosis (CE) or hydatid disease is a parasitic infection caused by Echinococcus granulosus. Early serodiagnosis and continuous monitoring of the disease is very important for medical treatment. Here, we report the detecting of both echinococcus antigen and antibody for the diagnosis of hydatid disease using square wave voltammetry (SWV)‐based immunosensors. The gold electrodes were functionalized using cysteamine/phenylene diisothiocyanate linkers and used for the immunosensors fabrication. The hydatid antigen and antibody immunosensors were constructed by the immobilization of either purified rabbit polyclonal antibody or recombinant antigen B (AgB), respectively on the functionalized gold electrodes surfaces. The detection in both cases was achieved by following the change in the SWV reduction peak current of the ferro/ferricyanide redox couple upon antibody or antigen binding. These immunosensors enabled the detection of echinococcus antigen and antibody within a concentration range of 1 pg.mL^?1 to 1 μg.mL^?1 with detection limits of 0.4 pg.mL^?1 and 0.3 pg.mL^?1, respectively. A preliminary application of the developed immunosensor was performed in spiked serum sample showing good recovery percentages ranging from 102 to 110 % for both hydatid antibody and antigen detection. This easy‐to‐use, sensitive, and low cost quantitative method holds great promise for the early diagnosis of hydatid disease and thus, better managements and treatment outcomes.     

In Vivo Imaging of the Tumor‐Associated Enzyme NCEH1 with a Covalent PET Probe

Herein, we report the development of an ¹⁸F‐labeled, activity‐based small‐molecule probe targeting the cancer‐associated serine hydrolase NCEH1. We undertook a focused medicinal chemistry campaign to simultaneously preserve potent and specific NCEH1 labeling in live cells and animals, while permitting facile ¹⁸F radionuclide incorporation required for PET imaging. The resulting molecule, [¹⁸F]JW199, labels active NCEH1 in live cells at nanomolar concentrations and greater than 1000‐fold selectivity relative to other serine hydrolases. [¹⁸F]JW199 displays rapid, NCEH1‐dependent accumulation in mouse tissues. Finally, we demonstrate that [¹⁸F]JW199 labels aggressive cancer tumor cells in vivo, which uncovered localized NCEH1 activity at the leading edge of triple‐negative breast cancer tumors, suggesting roles for NCEH1 in tumor aggressiveness and metastasis.