Nucleic acid aptamers specific to S-protein and its receptor binding domain (RBD) of SARS-CoV-2 (severe acute respiratory syndrome-related coronavirus 2) virions are of high interest as potential inhibitors of viral infection and recognizing elements in biosensors. Development of specific therapy and biosensors is complicated by an emergence of new viral strains bearing amino acid substitutions and probable differences in glycosylation sites. Here, we studied affinity of a set of aptamers to two Wuhan-type RBD of S-protein expressed in Chinese hamster ovary cell line and Pichia pastoris that differ in glycosylation patterns. The expression system for the RBD protein has significant effects, both on values of dissociation constants and relative efficacy of the aptamer binding. We propose glycosylation of the RBD as the main force for observed differences. Moreover, affinity of a several aptamers was affected by a site of biotinylation. Thus, the robustness of modified aptamers toward new virus variants should be carefully tested.

The recent severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has posed a great challenge for the development of ultra-fast methods for virus identification based on sensor principles. We created a structure modeling surface and size of the SARS-CoV-2 virus and used it in comparison with the standard antigen SARS-CoV-2—the receptor-binding domain (RBD) of the S-protein of the envelope of the SARS-CoV-2 virus from the Wuhan strain—for the development of detection of coronaviruses using a DNA-modified, surface-enhanced Raman scattering (SERS)-based aptasensor in sandwich mode: a primary aptamer attached to the plasmonic surface—RBD-covered Ag nanoparticle—the Cy3-labeled secondary aptamer. Fabricated novel hybrid plasmonic structures based on “Ag mirror-SiO₂-nanostructured Ag” demonstrate sensitivity for the detection of investigated analytes due to the combination of localized surface plasmons in nanostructured silver surface and the gap surface plasmons in a thin dielectric layer of SiO₂ between silver layers. A specific SERS signal has been obtained from SERS-active compounds with RBD-specific DNA aptamers that selectively bind to the S protein of synthetic virion (dissociation constants of DNA-aptamer complexes with protein in the range of 10 nM). The purpose of the study is to systematically analyze the combination of components in an aptamer-based sandwich system. A developed virus size simulating silver particles adsorbed on an aptamer-coated sensor provided a signal different from free RBD. The data obtained are consistent with the theory of signal amplification depending on the distance of the active compound from the amplifying surface and the nature of such a compound. The ability to detect the target virus due to specific interaction with such DNA is quantitatively controlled by the degree of the quenching SERS signal from the labeled compound. Developed indicator sandwich-type systems demonstrate high stability. Such a platform does not require special permissions to work with viruses. Therefore, our approach creates the promising basis for fostering the practical application of ultra-fast, amplification-free methods for detecting coronaviruses based on SARS-CoV-2.

Белок CD133 представляет собой крупный трансмембранный гликопротеин. Несмотря на большой объем проведенных исследований, роль CD133 в клетках до сих пор остается малопонятной. И хотя существующие на сегодняшний день данные разнятся, явно прослеживается связь CD133 с неопластической трансформацией. В данном обзоре резюмируются сведения по белку CD133, его структуре, регуляции экспрессии, молекулярных взаимодействиях и представленности в клетках, претерпевших онкотрансформацию. Доступная информация позволяет предположить, что CD133 может обладать большим прогностическим потенциалом для предсказания выживаемости при различных солидных опухолевых заболеваниях и служить одним из совокупных маркеров глиомы.

An alternative method for production of hybrid organic–inorganic nanocomposites based on porous polyolefin films (isotactic polypropylene, high density polyethylene), deformed via crazing mechanism in physically active media, and calcium phosphates is proposed. Film composite materials of different structure and containing 10–25 wt % of filler are obtained. Particles of calcium hydroxyapatite with a diameter of 15–50 nm are formed in these films at once in the pores of the polymer matrices with the development of a layer, the morphology of which is determined by the structure of the original porous films, and its parameters can be controlled by the reaction conditions. It is found that the composites obtained are characterized by anisotropy of mechanical properties, and the introduction of the calcium phosphate particles results in some increase in the mechanical characteristics of the polymer matrices. High-temperature heating (up to 700°C) of nanocomposites leads to burning out of the polymer matrix and formation of porous calcium hydroxyapatite residues consisting of nanoparticles with different morphology depending on the initial porous structure of polymer (from needle-shaped crystals with a length of 100–150 nm and about 10 nm in diameter to spheres with a diameter of 50–90 nm). The results obtained are relevant for the directional regulation of the structure and properties of bioactive substances and creation of modern materials for biomedical use.