Rationale: Colorectal cancer (CRC) is one of the most prevalent oncological diseases with high mortality. Invasive optical (endoscopic) colono- scopy has been recognized as a golden standard for the CRC diagnostics. A promising area is the development of non-invasive tools for CRC diagnosis with circular RNA (circRNA). One of the most sensitive non-invasive tools for detection of cancer RNA markers is considered to be the biosensor methods with the use of nanowire chips with oDNA probes (fragments of DNA oligonucleotides) immobilized on their surface. It has been previously shown that circRNA hsa_circ_0136666_CBC1, hsa_circ_0031263_CBC1, and hsa_circ_0072715_CBC1 are associated with CRC. Aim: To determine the lower limit of concentration sensitivity of detection of CRC-associated circRNA with nanowire chips with immobilized oDNA probes, to demonstrate the usability of these chips for non-invasive detection of circRNA in plasma in the CRC diagnostics, and to establish the potential for the use of nanowire chips for the early CRC diagnosis. Methods: To ensure biospecific binding of the circRNA hsa_circ_0136666_CBC1, hsa_circ_0031263_CBC1, and hsa_circ_0072715_CBC1 (the CRC markers), oDNA probes with the nucleotide sequences complementary to the target circRNA have been immobilized on the nanowire surface. At the study step 1, we detected the lower concentration limit for detection of the target molecules with the use of their analogues, i.e. synthetic model oDNA with the nucleotide sequences complementary to oDNA probes. At the study step 2, we used the nanowire chips with immobilized oDNA probes to detect the circRNA in plasma of the patients with confirmed CRC. Plasma samples from non-cancer patients were used as controls. Results: The lower concentration limit for the detection of DNA analogues of the circRNA hsa_circ_0136666_CBC1, hsa_circ_0031263_CBC1, and hsa_circ_0072715_CBC1 with nanowire chips with oDNA probes was 10-16 М. The analysis of total RNA isolated from plasma of the CRC patients showed a significant increase in the signal from the sensory elements of the nanowire chip. The analysis of plasma samples from the non-cancer patients, the nanowire signal changes were non-significant indicating the absence of detectable concentrations of the circRNA in plasma of the non-cancer patients. Conclusion: We have identified the minimal detectable concentration of the circRNA hsa_circ_0136666_CBC1, hsa_circ_0031263_CBC1, and hsa_circ_0072715_CBC1, associated to the development of CRC, with nanowire chips with immobilized oDNA probes: it was 10-16 М. The experiment showed the usability of such nanowire chips for non-invasive detection of the given circRNA markers in total RNA samples isolated from plasma of CRC patients.

Методом атомно-силовой микроскопии (АСМ) исследован пост-эффект движения глицерина по спиральной проточной системе на адсорбционные свойства белка пероксидазы хрена (ПХ), инкубированного вблизи линейной части выходной части проточной системы.

Experimental methods of single-molecule enzymology allow scientists to determine physicochemical properties of distinct single molecules of various enzymes and to perform direct monitoring of functioning of enzymes at different steps of their catalytic cycle. The approach based on the use of solid-state nanopores is a promising tool for studying the functioning of single-enzyme molecules. Herein, this approach is employed for monitoring the functioning of cytochrome P450 BM3, which represents a very convenient model of cytochrome P450-containing monooxygenase systems. A nanopore of ~5 nm in diameter has been formed in a 40 nm-thick silicon nitride chip by electron beam drilling (EBD), and a single molecule of the BM3 enzyme has been entrapped in the pore. The functioning of the enzyme molecule has been monitored by recording the time dependence of the ion current through the nanopore during the reaction of laurate hydroxylation. In our experiments, the enzyme molecule has been found to be active for 1500 s. The results of our research can be further used in the development of highly sensitive detectors for single-molecule studies in enzymology.

Aim. The possibility of using a nanopore to monitor the functioning of asparaginase has been studied.Methodology. In this work, a SiN-based nanopore was constructed in which the L-asparaginase molecule was embedded. The catalytic activity of the L-asparaginase molecule, embedded in the nanopore, has been monitored by observing the change in the ion current in the cell with this nanopore. This approach is useful for studying the catalytic activity based on single enzyme molecules embedded in a nanopore.Results. A nanopore detector for studying the catalytic activity of L-asparaginase has been developed. It has been found that this detector made it possible to monitor the activity of this enzyme.Research implications. It has been shown that a nanopore detector, with a nanopore size of the order of 6 nm, can be used to study the activity of asparaginase. It is possible to carry out realtime monitoring of changes in the form of L-asparaginase, which consisted in monitoring changes in the ion current passing through a nanopore, in which asparaginase was immobilized. The results obtained can be of use in the analysis of the functioning of enzymes at the level of single molecules.

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.