The influence of liquid motion in flow-based systems on the aggregation state of an enzyme and on its enzymatic activity was studied, with horseradish peroxidase (HRP) as an example. Our experiments ...were carried out in a setup modeling the flow section of the biosensor communication with a measuring cell containing a protein solution. Studies were conducted for a biosensor measuring cell located along the axis of a spiral-moving liquid flow. The aggregation state of the protein was determined with an atomic force microscopy-based sensor (AFM sensor). It has been demonstrated that upon flowing of water through silicone biosensor communications, an increased aggregation of HRP protein was observed, but, at the same time, its enzymatic activity did not change. Our results obtained herein are useful in the development of models describing the influence of liquid flow in biosensor communications on the properties of enzymes and other proteins. This is particularly important for the development of serologic protein biosensors, which are beginning to be used for the early diagnosis of oncological diseases (such as brain cancer, prostate cancer, breast cancer etc.). The results obtained herein should also be taken into account when considering possible changes in hemodynamics due to increased protein aggregation.
Introduction. The COVID-19 pandemic, etiologically related to SARS-CoV-2, was the longest-lasting pandemic for an acute respiratory disease and had a significant impact on demography, economics and ...politics globally. Experiences with this pandemic are significant for the sustainable development of human society. A detailed analysis of these experiences in epidemic control should include details of the pathogen evolution down to the regional level. The aim of the study was to establish the regularities of the COVID-19 epidemic process in connection with the change of the pathogen genetic variants on the territory of Primorsky Krai. Materials and methods. A retrospective epidemiological analysis of COVID-19 incidence and dynamics of circulation of SARS-CoV-2 genetic variants during the pandemic of this disease (11.03.2020–05.05.2023) in Primorsky Krai was carried out. Data was gathered from the Department of Rospotrebnadzor in Primorsky Krai, the Centre of Hygiene and Epidemiology in Primorsky Krai, as well as the G.P. Somov Research Institute of Epidemiology and Microbiology of the Russian Federation and Russian Platform for Aggregation of Information on Virus Genomes (VGARus). In particular, 1055 nucleotide sequences of full-length SARS-CoV-2 genomes from Primorsky Krai, among which 553 were sequenced at the G.P. Somov Research Institute of Epidemiology and Microbiology were included in analysis. Results. When analyzing the epidemic dynamics of COVID-19 in Primorsky Krai (2020–2023), 7 rises in incidence with different clinical and epidemiological symptoms depending on the genetic variants of the pathogen were identified. At the beginning of the pandemic in Primorsky Krai, as well as throughout Russia, Wuhan-like variants of SARS-CoV-2 were predominant, though later, Delta and Omicron genetic variants were in the majority. By the end of April — beginning of May 2023, the proportion of Omicron sub-variants (XBB.1.9.2 and XBB.1.16) in Primorsky Krai was higher than the Russian average and comparable to that in neighboring countries (Republic of Korea and Japan). Conclusion. Due to the ongoing evolution of SARS-CoV-2, the possibility of the emergence of new pathogens, the peculiarities of the geographical location as well as political and economic importance of Primorsky Krai, it is necessary to consistently improve regional capabilities for operational molecular virological monitoring.
Herein, we have demonstrated highly sensitive real-time biospecific detection of a protein marker of hepatitis C—the core antigen of hepatitis C virus (HCVcoreAg)—using a nanowire (NW) biosensor. The ...primary element of the NW-biosensor is a chip with p-type conductance, bearing silicon-on-insulator (SOI) nanowire structures on its surface. The nanowire structures are fabricated by gas-plasma treatment and electron beam lithography. The detection specificity was provided by sensitization of the sensor surface with aptamers against HCVcoreAg. The influence of buffer pH on the sensor response signal was studied. The effect of reverse polarity of the biosensor response signal with change from the acidic buffer pH to the neutral one was found. The lowest detectable HCVcoreAg concentration was determined to be 2.0 × 10−15 M in both acidic (pH 5.1) and neutral (pH 7.4) buffer solution. The proposed aptamer-sensitized sensor was also successfully applied to detect HCVcoreAg in serum samples of hepatitis C patients.
Herein, we report the development of a highly sensitive nanotechnology-based system—silicon-on-insulator nanowire biosensor for the revelation of microRNAs (miRNAs), associated with the development ...of glioma in the human. In this system, a sensor chip, bearing an array of silicon nanowire structures, is employed. The sensor chip is fabricated using a top-down technology. In our experiments reported herein, we demonstrated the detection of DNA oligonucleotide (oDNA), which represents a synthetic analogue of microRNA-363 associated with the development of glioma. To provide biospecific detection of the target oligonucleotides, the surface of the nanowire structures is modified with oligonucleotide probes; the latter are complementary to the target ones. The concentration limit of the target oligonucleotide detection, attained using our nanowire biosensor, is at the level of DL~10−17 M. The revelation of the elevated level of glioma-associated miRNA in plasma is also demonstrated.
•A crystalline form of S6-С60(CF3)12 was synthesized in an amount sufficient for reliable experimental investigation.•The melting point and solubility of S6-С60(CF3)12 were observed.•The enthalpy of ...combustion and heat capacity of S6-С60(CF3)12 in oxygen was determined.•The thermodynamic functions (namely the enthalpy of formation, the entropy and the Gibbs energy) ofS6-С60(CF3)12 were determined.•The estimation of the energy of formation for a set of trifluoromethylfullerenes were reported.
A crystalline form of S6-С60(CF3)12 was synthesized in an amount sufficient for reliable experimental investigation. We determined the enthalpy of combustion of S6-С60(CF3)12 in oxygen and its heat capacity, which made possible to derive the thermodynamic functions of S6-С60(CF3)12, namely the enthalpy of formation, the entropy and the Gibbs energy at T=298.15K. These experimental thermochemical data enabled estimation of the formation energy for a broad range of other trifluoromethylated compounds C60(CF3)n, with n=(2–18; 24), on the basis of their DFT calculated relative energies.
Taxonomic and quantitative composition of Foraminifera assemblages in the Zhitkov Bay (Russky Island, Peter the Great Bay, Japan Sea) are described. In total, 52 species from 30 genera and 14 ...families of benthic foraminifera have been identified in bottom sediments. The most of them are represented by calcareous forms (38 species), with the highest abundance of families Elphidiidae, Discorbidae, and Buliminidae, other are 14 species of agglutinated foraminifera, including 2 common species of families Trochamminidae and Ataxophragmiidae. Population density of benthic foraminifera correlates well with the type of bottom sediments: the highest abundance is observed on alenric sediments and pebble-sandy grounds and the lowest abundance - on fine-grained pelitic sediments. Six assemblages of benthic foraminifera are determined for the Zhitkov Bay, taking into account the prevailing families.
p-Azidophenyl phosphate (
I) has been exposed to ultraviolet light (
λ=313 nm) in aqueous solution with or without Lys. Analysis of the photoproducts by means of UV–VIS, IR,
1H,
13C and
31P NMR ...spectroscopy has revealed that under irradiation of
I inorganic phosphate (P
i) is released, and
p-benzoquinone monoimine (
II) and
p-benzoquinone (
III) have appeared. The electrophilic nature of the intermediate results in a high tendency to react with lysine molecules, whereas the reaction with water is less favourable when
I is irradiated in the presence of Lys. The product formed in this case is a phosphoramidate whose structure has been tentatively supported by
31P NMR spectroscopy. These results imply that a
p-azidophenyl phosphate is a highly potent aryl nitrene-precursor, which can be transformed easily into
p-benzoquinone monoimine and is able to phosphorylate nucleophilic groups of amino acids. This finding is of great importance for the discussions about the chemical nature of protein photomodification products when
p-azidophenyl phosphate derivatives are used as modifying reagents.
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