In-Situ Electrochemical Exfoliation and Methylation of Black Phosphorus into Functionalized Phosphorene Nanosheets.

Two-dimensional black phosphorus (BP) has attracted great attention as a perspective material for various applications. The chemical functionalization of BP is an important pathway for the preparation of materials with improved stability and enhanced intrinsic electronic properties. Currently, most of the methods for BP functionalization with organic substrates require either the use of low-stable precursors of highly reactive intermediates or the use of difficult-to-manufacture and flammable BP intercalates. Herein we report a facile route for simultaneous electrochemical exfoliation and methylation of BP. Conducting the cathodic exfoliation of BP in the presence of iodomethane makes it possible to generate highly active methyl radicals, which readily react with the electrode's surface yielding the functionalized material. The covalent functionalization of BP nanosheets with the P-C bond formation has been proven by various microscopic and spectroscopic methods. The functionalization degree estimated by solid-state 31P NMR spectroscopy analysis reached 9.7%.

PNP Ligands in Cobalt-Mediated Activation and Functionalization of White Phosphorus.

Transition-metal mediated white phosphorus activation is of high interest as an ecological alternative to P4 chlorination pathway to the practically useful phosphorus products. Herein, we report a facile approach for P4 activation, transformation and subsequent functionalization using cobalt complexes bearing PNP ligands. The use of N,N-bis(diphenylphosphino)amine as a ligand allows one to transform P4 tetrahedron into a zig-zag chain with the formation of complex [Co(Ph2 PNHP(Ph2 )PPPPP(Ph2 )NHPPh2 )]BF4 (4). The presence of organic substituent at nitrogen atom in PNP ligand enables one to obtain complexes with η1 -coordinated P4 molecule, which indicates a crucial role of N-H bond in transformation of white phosphorus tetrahedron. Additionally, complex 4 can readily be functionalized by means of the reaction with Ph2 PCl leading to the formation of a new complex bearing unique P9 -ligand. The obtained results provide opportunities for facile construction of new polyphosphorus ligands in the coordination sphere of transition metal complexes.

Variation in tumor pH affects pH-triggered delivery of peptide-modified magnetic nanoparticles.

Acidification of the extracellular matrix, an intrinsic characteristic of many solid tumors, is widely exploited for physiologically triggered delivery of contrast agents, drugs, and nanoparticles to tumor. However, pH of tumor microenvironment shows intra- and inter-tumor variation. Herein, we investigate the impact of this variation on pH-triggered delivery of magnetic nanoparticles (MNPs) modified with pH-(low)-insertion peptide (pHLIP). Fluorescent flow cytometry, laser confocal scanning microscopy and transmission electron microscopy data proved that pHLIP-conjugated MNPs interacted with 4T1 cells in two-dimensional culture and in spheroids more effectively at pH 6.4 than at pH 7.2, and entered the cell via clathrin-independent endocytosis. The accumulation efficiency of pHLIP-conjugated MNPs in 4T1 tumors after their intravenous injection, monitored in vivo by magnetic resonance imaging, showed variation. Analysis of the tumor pH profiles recorded with implementation of original nanoprobe pH sensor, revealed obvious correlation between pH measured in the tumor with the amount of accumulated MNPs.

Hydrolysis of Element (White) Phosphorus under the Action of Heterometallic Cubane-Type Cluster {Mo3PdS4}.

Reaction of heterometallic cubane-type cluster complexes-[Mo3{Pd(dba)}S4Cl3(dbbpy)3]PF6, [Mo3{Pd(tu)}S4Cl3(dbbpy)3]Cl and [Mo3{Pd(dba)}S4(acac)3(py)3]PF6, where dba-dibenzylideneacetone, dbbpy-4,4'-di-tert-butyl-2,2'-bipyridine, tu-thiourea, acac-acetylacetonate, py-pyridine, with white phosphorus (P4) in the presence of water leads to the formation of phosphorous acid H3PO3 as the major product. The crucial role of the Pd atom in the cluster core {Mo3PdS4} has been established in the hydrolytic activation of P4 molecule. The main intermediate of the process, the cluster complex [Mo3{PdP(OH)3}S4Cl3(dbbpy)3]+ with coordinated P(OH)3 molecule and phosphine PH3, have been detected by 31P NMR spectroscopy in the reaction mixture.

Effect of genetic polymorphisms in CA6 gene on the expression and catalytic activity of human salivary carbonic anhydrase VI.

Carbonic anhydrase isoenzyme VI (CA VI) plays an important role in the homeostasis of oral tissues participating in the processes of taste, protection of dental tissues against the loss of minerals, caries, and possibly in the formation of dental calculus in periodontal disease. This study aimed to verify the correlation between changes in the expression and activity of human salivary carbonic anhydrase VI and genetic polymorphisms in its gene (CA6). The study population consisted of 182 healthy volunteers (female and male, aged 18-22). Samples of total saliva were assayed for CA VI concentrations using a specific time-resolved immunofluorometric assay. CA VI catalytic activity was detected by a modified protocol of Kotwica et al. [J Physiol Pharmacol 2006;57(suppl 8):107-123], adapted to CA VI in saliva. Samples of genomic DNA were genotyped for polymorphisms rs2274327 (C/T), rs2274328 (A/C) and rs2274333 (A/G) by TaqMan® SNP Genotyping Assays. The concentration and catalytic activity of the salivary CA VI obtained for the different genotypes were analyzed using the Kruskal-Wallis nonparametric test and the Dunn test. The results showed that individuals with TT genotype (rs2274327) had significantly lower CA VI concentrations than the individuals with genotypes CT or CC (p < 0.05). There was also an association between polymorphism rs2274333 and salivary CA VI concentrations. There were no associations between the three polymorphisms analyzed and variations in CA VI activity. Our results suggest that polymorphisms in the CA6 gene are associated with the concentrations of secreted CA VI.

Covalent Functionalization of Black Phosphorus Nanosheets with Dichlorocarbenes for Enhanced Electrocatalytic Hydrogen Evolution Reaction.

Two-dimensional black phosphorus (BP) has emerged as a perspective material for various micro- and opto-electronic, energy, catalytic, and biomedical applications. Chemical functionalization of black phosphorus nanosheets (BPNS) is an important pathway for the preparation of materials with improved ambient stability and enhanced physical properties. Currently, the covalent functionalization of BPNS with highly reactive intermediates, such as carbon-free radicals or nitrenes, has been widely implemented to modify the material's surface. However, it should be noted that this field requires more in-depth research and new developments. Herein, we report for the first time the covalent carbene functionalization of BPNS using dichlorocarbene as a functionalizing agent. The P-C bond formation in the obtained material (BP-CCl2) has been confirmed by Raman, solid-state 31P NMR, IR, and X-ray photoelectron spectroscopy methods. The BP-CCl2 nanosheets exhibit an enhanced electrocatalytic hydrogen evolution reaction (HER) performance with an overpotential of 442 mV at -1 mA cm-2 and a Tafel slope of 120 mV dec-1, outperforming the pristine BPNS.

Evidence for flock transmission of individual subtypes and strains of avian influenza viruses: A monitoring study of wild birds in Kazakhstan.

An active surveillance study of avian influenza viruses (AIVs) in wild birds was carried out in Kazakhstan in 2018-2019. In total, 866 samples were collected from wild birds and analyzed for influenza viruses using molecular and virological tests. Genome segments of Asian, European, and Australian lineages were detected in 25 (4.6%) out of 541 waterfowl samples positive for subtype H3N8, and in two (0.6%) out of 325 H3N8 positive samples from terrestrial birds. No highly pathogenic avian influenza virus (AIV) was detected. The results indicated transmission of closely related strains or identical subtypes of AIVs by a flock-unit of migratory birds or annual cyclical pattern of subtype dominance. The simultaneous circulation of genome segments of the Asian, European and Australian genetic lineages of H3N8 AIVs in wild birds in Kazakhstan indicated the important role of Central Asia as a transmission hub of AI viruses linking the East Asian migratory flyways with European flyways and vice versa.

The Prevalence of Pathogens among Ticks Collected from Livestock in Kazakhstan.

Ticks carry and transmit a wide variety of pathogens (bacteria, viruses and protozoa) that pose a threat to humans and animals worldwide. The purpose of this work was to study ticks collected in different regions of Kazakhstan for the carriage of various pathogens. The collected ticks were examined by PCR for the carriage of various pathogens. A total of 3341 tick samples parasitizing three animal species (cattle, sheep and horses) were collected at eight regions of Kazakhstan. Eight tick species were found infesting animals: Dermacentor marginatus (28.08%), Hyalomma asiaticum (21.28%), Hyalomma anatolicum (17.18%), Dermacentor reticulatus (2.01%), Ixodes ricinus (3.35%), Ixodes persulcatus (0.33%), Hyalomma scupense (12.87%) and Hyalomma marginatum (14.90%). Ticks collected from livestock animals were examined for the pathogen spectrum of transmissible infections to determine the degree of their infection. Four pathogen DNAs (lumpy skin disease virus (LSDV), Coxiella burnetti, Teileria annulata, and Babesia caballi) were detected by PCR in Dermacentor marginatus, Hyalomma asiaticum, Hyalomma scupense, Hyalomma anatolicum. The infection of ticks Dermacentor marginatus and Hyalomma asiaticum collected on cattle in the West Kazakhstan region with LSDV was 14.28% and 5.71%, respectively. Coxiella burnetti was found in the ticks Dermacentor marginatus (31.91%) in the Turkestan region and Hyalomma anatolicum (52.63%) in the Zhambyl region. Theileria annulata was found in ticks Hyalomma scupense (7.32%) and Dermacentor marginatus (6.10%) from cattle in the Turkestan region. Babesia caballi was isolated only from the species Hyalomma scupense (17.14%) in the Turkestan region. There were no PCR-positive tick samples collected from sheep. RNA/DNAs of tick-borne encephalitis virus (TBEV), African swine fever virus (ASFV), Hantavirus hemorrhagic fever with renal syndrome (HFRS), and chlamydia pathogens were not found in ticks. The new data give a better understanding of the epidemiology of tick-borne pathogens and the possibility of the emergence of tick-borne animal diseases in Kazakhstan.

Smart Design of a pH-Responsive System Based on pHLIP-Modified Magnetite Nanoparticles for Tumor MRI.

Magnetic Fe3O4 nanoparticles (MNPs) are often used to design agents enhancing contrast in magnetic resonance imaging (MRI) that can be considered as one of the efficient methods for cancer diagnostics. At present, increasing the specificity of the MRI contrast agent accumulation in tumor tissues remains an open question and attracts the attention of a wide range of researchers. One of the modern methods for enhancing the efficiency of contrast agents is the use of molecules for tumor acidic microenvironment targeting, for example, pH-low insertion peptide (pHLIP). We designed novel organosilicon MNPs covered with poly(ethylene glycol) (PEG) and covalently modified by pHLIP. To study the specific features of the binding of pHLIP-modified MNPs to cells, we also obtained nanoconjugates with Cy5 fluorescent dye embedded in the SiO2 shell. The nanoconjugates obtained were characterized by transmission electron microscopy (TEM), attenuated total reflection (ATR), diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), dynamic light scattering (DLS), UV and fluorescence spectrometry, thermogravimetric analysis (TGA), CHN elemental analyses, and vibrating sample magnetometry. Low cytotoxicity and high specificity of cellular uptake of pHLIP-modified MNPs at pH 6.4 versus 7.4 (up to 23-fold) were demonstrated in vitro. The dynamics of the nanoconjugate accumulation in the 4T1 breast cancer orthotopically grown in BALB/c mice and MDA-MB231 xenografts was evaluated in MRI experiments. Biodistribution and biocompatibility studies of the obtained nanoconjugate showed no pathological change in organs and in the blood biochemical parameters of mice after MNP administration. A high accumulation rate of pHLIP-modified MNPs in tumor compared with PEGylated MNPs after their intravenous administration was demonstrated. Thus, we propose a promising approach to design an MRI agent with the tumor acidic microenvironment targeting ability.

Platinum-Catalyzed Hydrosilylation in Polymer Chemistry.

This paper addresses a review of platinum-based hydrosilylation catalysts. The main field of application of these catalysts is the curing of silicone polymers. Since the 1960s, this area has developed rapidly in connection with the emergence of new polymer compositions and new areas of application. Here we describe general mechanisms of the catalyst activity and the structural effects of the ligands on activity and stability of the catalysts together with the methods for their synthesis.

L-Lysine-modified Fe3O4 nanoparticles for magnetic cell labeling.

The efficiency of magnetic labeling with L-Lys-modified Fe3O4 magnetic nanoparticles (MNPs) and the stability of magnetization of rat adipose-derived mesenchymal stem cells, lineage-negative (Lin(-)) hematopoietic progenitor cells from mouse bone marrow and human leukemia K562 cells were studied. For this purpose, covalent modification of MNPs with 3-aminopropylsilane and N-di-Fmoc-L-lysine followed by removal of N-protecting groups was carried out. Since the degree of hydroxylation of the surface of the starting nanoparticles plays a crucial role in the silanization reaction and the possibility of obtaining stable colloidal solutions. In present work we for the first time performed a comparative qualitative and quantitative evaluation of the number of adsorbed water molecules and hydroxyl groups on the surface of chemically and physically obtained Fe3O4 MNPs using comprehensive FTIR spectroscopy and thermogravimetric analysis. The results obtained can be further used for magnetic labeling of cells in experiments in vitro and in vivo.

[Clinical and laboratory diagnosis of heart disease in systemic lupus erythematosus]. / Avaliação clínica e laboratorial da cardiopatia no lúpus eritematoso sistêmico.

PURPOSE: To examine heart disease in the systemic lupus erythematosus (SLE) and the association of cardiac abnormalities with anticardiolipin antibodies (ACL). METHODS: Sixteen patients with active SLE disease (group I) were compared with 14 patients without disease activity (group II). A control group of 10 healthy subjects were also evaluated. Patients were subjected to cardiovascular history and physical examination as well as electrocardiogram, thoracic x-ray, two-dimensional and Doppler echocardiogram, and ACL serum determination (ELISA). RESULTS: Myocardial disease characterized by tachycardia, heart failure or echocardiographic abnormalities was shown by 75% of patients in the group I. It was associated with ACL positive in 27.2% of these patients. Pericardial and valvular involvement were observed in 25% of patients in group I. Group II showed myocardial involvement in 21.4% of patients without positive ACL. CONCLUSION: Myocardial disease was the most frequent heart involvement in active SLE, and we did not found any association between SLE heart disease and positive anticardiolipin antibodies.