Oleg Fedorovich Petrov

Generally, cancer is responsible for nearly every sixth death worldwide. Early cancer revelation can provide successful and low-cost treatment of cancer, enhancing survival rates of cancer patients. This explains the key importance of development of novel highly sensitive systems for revelation of cancers in humans. Ribonucleic acids (RNAs) of several different types (microRNAs, circular RNAs, and small nucleolar RNAs) represent promising cancer biomarkers. At the same time, nanoribbon biosensors allow one to detect cancer-associated RNAs at ultra-low concentrations. Here we focus at experimental results on the detection of cancer-associated RNAs in human plasma with our nanoribbon biosensor, demonstrating promising capabilities of this nanotechnology-based device as a base of highly efficient diagnostic screening platform for early diagnosis of cancers in humans.

Heme-containing enzymes play vital functions in living organisms, including humans. Here we demonstrate two indirect effects of (electric discharge)-treated stainless steel on a model enzyme — horseradish peroxidase (HRP). The first effect is the complete loss of the enzyme’s adsorption after its incubation in grounded stainless steel chamber, which has been preliminarily subjected to electric discharge in air at atmospheric pressure. The second one is the formation of enzyme aggregates in the sample incubated in another grounded chamber two meters away from the discharge-treated one. At that, the HRP’s enzymatic activity is found to be unaffected in the both cases. These effects may be explained by the occurrence of knotted electromagnetic fields (KEMF). By using high-speed atomic force microscopy (HS-AFM), we reveal the relatively high surface mobility of cytochromes P450cam and P450 102A1 (BM3), whose isoelectric point (pI) values are acidic; at that, thymidylate synthase (TYMS) with near-neutral pI adsorbs strongly. Thus, HRP is the best model object, since its basic pI provides quite strong adsorption on mica. Since (electric discharge)-processed materials have found applications in medicine, we expect that the effects discovered will be considered in future biomedical applications of (electric discharge)-based technologies.

The synthesis of nanoparticles in the plasma of a stratified DC gas discharge was carried out under typical gas discharge conditions, i.e., at room temperature and an argon pressure of 0.11 torr, with a discharge current of 2.5 mA. The particles were formed and grown due to the sputtering of a dielectric plasma concentrator, which was used for strata stabilization. The analysis of the material collected using double-sided carbon tape placed on the glass wall of the discharge tube was performed by scanning electron microscopy and X-ray energy-dispersive microanalysis after the experiments. Three distinctive groups of particles of different shape and size were found, i.e., smooth spherical nanoparticles with a size of 10–100 nm, the main group of smooth spherical and dumbbell-like particles with a size of 200–500 nm, and micron-sized particles of complex cauliflower-like shape. EDX microanalysis of the synthesized nanoparticles revealed that the particles mainly consist of C, O, and Si, which proves that they were formed from the sputtered material of the silicone dielectric concentrator. Analysis of the particles and plasma parameters was performed, and a probable mechanism for the formation of such particles is proposed.

Renal cell carcinoma is the most common form of kidney cancer (more than 90 % of all oncological pathologies of the kidney). At an early stage of development, renal cell carcinoma can be asymptomatic, and this significantly complicates its diagnosis. Commonly used methods for diagnosing renal cell carcinoma do not allow for timely detection of this disease at early stages, thus it is necessary to develop effective and non-invasive methods for its diagnosis using biological macromolecules detectable in blood – biomarkers of this type of cancer. Small nucleolar RNAs are of great interest as such biological macromolecules. In this study, a SiNW biosensor was designed and manufactured for the direct detection of small nucleolar RNA SNORA77 in the blood, associated with renal cell carcinoma. The key element of the SiNW biosensor developed is a nanowire chip based on “siliconon- insulator” structures. The chip is manufactured using a technology similar to Smart Cut, and contains an array of silicon nanowires with n-type conductivity, on whose surface DNA oligonucleotide probes are covalently immobilized. To ensure the specificity of the analysis, the nucleotide sequence of the immobilized DNA probes is complementary to the target sequence of the small nucleolar RNA SNORA77. Purified buffer solutions containing various concentrations of synthetic DNA oligonucleotides, whose sequence is similar to the target detectable sequence of SNORA77, have been analyzed. Using the SiNW biosensor developed, the detection limit of SNORA77 was determined to be approximately 10–17 M. The SiNW biosensor has allowed us to detect an elevated level of SNORA77 in a sample isolated from the blood plasma of a patient with confirmed diagnosis of renal cell carcinoma in comparison with that in a control sample isolated from the plasma of a patient with a non-oncologic disease. The results of the study will be useful for further development of early diagnostic systems for renal cell carcinoma.

This work investigates the unidirectional transport of charged particles across magnetic field lines driven by magnetosonic solitons in a collisionless plasma. Within the framework of a magnetohydrodynamic model, numerical solutions as well as analytical expressions for small-amplitude solitons are obtained, and it is shown that particles experience a unidirectional displacement proportional to the square root of the wave amplitude, indicating that solitons generate substantial matter transport across the magnetic field.

Urogenital cancers represent one of leading causes of death, and thus novel simple, highly sensitive and reliable methods are required for their revelation at early stages in order to provide effective therapy and improve patients’ survival rate. Here we demonstrate parallel rapid label-free detection of a pool of (urogenital cancer)-associated non-coding RNA molecules of three different types — microRNAs, circular RNAs (circRNAs) and small nucleolar RNAs (snoRNAs) — in human blood with sub-femtomolar concentration sensitivity. This is achieved by employing a biosensor, whose nanotechnology-based sensor chip bears an array of oligonucleotide-sensitised silicon-on-insulator (SOI) nanoribbons fabricated using a ‘top-down’ technology. The simultaneous detection of different types of cancer-associated ncRNAs in one sample will increase the reliability of the diagnostic results, helping to avoid both false-positives and false-negatives. Owing to the high detection sensitivity, which reaches several thousands of target ncRNA molecules in 1 mL of the analysed sample, the nanoribbon biosensor proposed herein represents a promising tool for early revelation of urogenital cancers in humans.

Background/Objectives: Fluorothiazinone (FT), a small molecule of the 2,4-disubstituted-4H-[1,3,4]-thiadiazine-5-one class, is known to inhibit the type III secretion system (T3SS) in Gram-negative bacteria and has shown therapeutic potential in animal models and clinical trials. Given the evolutionary relationship between the T3SS and the bacterial flagellar apparatus, this study aimed to investigate the effects of FT on bacterial motility and flagellum assembly. Methods: Motility was assessed in Pseudomonas aeruginosa, Proteus mirabilis, pathogenic Escherichia coli, and Listeria monocytogenes using a semisolid agar assay and a microfluidic motility system. The mechanism of FT’s action was further examined through time-course analysis, Western blotting of surface flagella proteins, and transmission electron microscopy (TEM). Results: FT inhibited motility of P. aeruginosa, P. mirabilis, and E. coli in a dose-dependent manner, while L. monocytogenes motility remained unaffected. The inhibitory effect was not immediate but delayed 2–3 h post FT addition. Western blotting revealed the absence of surface flagella in EHEC grown with FT, and TEM confirmed structural disruption of flagella in P. mirabilis. Conclusions: FT selectively inhibits flagellum-based motility in Gram-negative bacteria. Obtained data suggested FT interference with flagellum biosynthesis rather than disruption of rotation. Motility inhibition can contribute to FT therapeutic effects on Gram-negative bacterial infections.

The influence of laser-induced active Brownian motion on dust-acoustic instability in the colloidal plasma of a direct current glow discharge was experimentally studied. The dust structure was formed by spherical monodisperse melamine-formaldehyde particles with a partial copper coating (Janus particles). It is shown that with increasing laser radiation intensity, a self-excited plane dust-acoustic wave decays. At an intensity of ≈1.5 W/cm2, the wave ceases to be observed in a three-dimensional plasma–dust cloud. As the intensity decreases, the wave is excited again, which indicates the reversibility of the process. The results obtained can be used to control collective plasma processes.