A biosensor based on field-effect transistors on silicon-on-insulator structures (SOI-biosensor) is a high-potential device for detection of biological molecules, for instance, such as troponin I; the biosensor allows conducting label-free real-time analysis.The aim of the study is the development of SOI-biosensor design for detection of acute myocardial infarction marker -troponin I.A notable feature of this design was the integration of two grounding electrodes directly onto the biosensor surface, which effectively nullified the static potential of the liquid sample and minimized physical breakdowns of biosensor elements.Materials and Methods.The highly specific anti-troponin I DNA aptamer was used as a receptor for specific detection of protein marker.Aptamer immobilization on the biosensor surface was carried out by physical adsorption.The analyzed range of target troponin I molecules concentration in the sample varied within 10 -11 to 10 -9 mol/L, mirroring clinical levels observed in myocardial infarction cases.During the experiment, a constant voltage of V ds =0.15 V was maintained.Results.The developed SOI-biosensor successfully detected target troponin I molecules at a concentration of 10 -11 mol/L.The detection process exhibited an effective time of approximately 200-300 s per sample.Moreover, analysis of the detection process revealed a noticeable decrease in current within the source-drain circuit, indicative of the negatively charged complex formed by troponin I and anti-troponin I DNA-aptamer at the "liquid sample-nanowire" phase interface.

Detection of virus in sample is an actual problem in biotechnology, virology, medicine using biosensor. History of problem dates back to middle of last century and is associated with development of an ion-sensitive solid-state device for neurophysiological measurements. Aim of work is theoretical investigation process of detection antibody+antigen (AB+AG) complexes using SOI-FET biosensor. On example of crystal with ten biosensors, estimates of probability detection AB+AG complexes influenza virus are made. In detection process, following four results are possible: – target complex is present in test sample, and it was correctly detected; – target complex is present in sample, but it was not detected; – target complex is absent in sample, but background particles are mistakenly detected as target complex; – target complex is absent in sample, background particles present in sample and are correctly detected as noise.

The SOI-FET biosensor (silicon-on-insulator field-effect transistor) for virus detection is a promising device in the fields of medicine, virology, biotechnology, and the environment. However, the applications of modern biosensors face numerous problems and require improvement. Some of these problems can be attributed to sensor design, while others can be attributed to technological limitations. The aim of this work is to conduct a theoretical investigation of the “antibody + antigen” complex (AB + AG) detection processes of a SOI-FET biosensor, which may also solve some of the aforementioned problems. Our investigation concentrates on the analysis of the probability of AB + AG complex detection and evaluation. Poisson probability density distribution was used to estimate the probability of the adsorption of the target molecules on the biosensor’s surface and, consequently, to obtain correct detection results. Many implicit and unexpected causes of error detection have been identified for AB + AG complexes using SOI-FET biosensors. We showed that accuracy and time of detection depend on the number of SOI-FET biosensors on a crystal.

Objective: The purpose is to identify the peculiarities of the parameters of red blood cells (RBC) and hemostasis in patients with strokes associated with coronavirus infection. Design and method: A total of 124 patients (48.5 + 1.9 years) with impairments of cerebral circulation due to COVID-19 (confirmed by positive PCR test) had been examined. Among them, 74 patients had ischemic stroke, 25– transient ischaemic attack, 17– intracerebral hemorrhage, 8– subarachnoid hemorrhage. The parameters of hemostasis were measured by standard methods, electrical, viscoelastic parameters of RBC - by dielectrophoresis. Results: 71 patients (the 1st group) showed signs of intravascular coagulation and thrombosis: accelerated platelet-leukocyte aggregation, increased levels of coagulation products, reduced fibrinolysis activity (p = 0.001–0.04). The levels of D-dimer, fibrinogen, ESR, platelet count were higher in this group compared to the second one (p < 0.01). A moderate increase of RBC summarized rigidity, viscosity was noted. The level of RBC hemolysis was associated with platelet count (r = 0.735,p = 0.03), D-dimer (r = 0.482, p < 0.05), fibrinogen level (r = 0.374, p = 0.04). In 2nd group (53 persons), the markers of thrombosis had moderate deviations. Sharply reduced RBC deformability with increased summarized rigidity, viscosity was dominant coupled with the background of high electrical conductivity of cell membranes compared to the indicators in the 1st group (p < 0.01). There was a decrease of membrane capacity, surface charge, cell dipole moment, polarizability than those in the 1st group (p = 0.0001–0.05). A sharp decrease of RBC deformability creates obstacles to overcoming small-diameter capillaries, leading to violations of microcirculatory blood flow. RBC deformability was associated with levels of ferritin (r = 0.451, p = 0.02), HbA1c (r = 0.480, p = 0.03), uric acid (r = -0.371, p < 0.05), LDL cholesterol (r = 0.461, p = 0.02). Incubation of blood samples in vitro for 10 min with riboflavin, nicotinamide, inosine, which ensures RBC energy metabolism, restored the reduced RBC deformability (p < 0.01), altered cell morphology (p = 0.04), decreased RBC aggregation (p < 0.001). Conclusions: The revealed features of parameters of RBC hemostasis in stroke patients with coronavirus infection are associated with two independent pathogenetic mechanisms: thrombotic and hemorheologic. The thrombotic variant is due to procoagulant state and an activity of inflammation. The hemorheologic variant is caused by decrease of RBC energy metabolism, activity of enzymes.

Biosensor based on a silicon nanowire field-effect transistor is a new analytical device for viral detection. The principle of operation of biosensors based on modulates the current in the source-drain circuit of the transistor during interactions antibody with viral particles on nanowire surface. In this study detections of viral particles using biosensor was performed. For this experiment the surface of a biosensor based on a silicon nanowire field-effect transistor for the detection of viral particles was prepared. The time dependence of the biosensor current was controlled by a recording device which was developed at Novosibirsk State University. In the results is showed that viral particles have a positive electric charge on the surface of the “nanowire - solution phase” interface, the “antibody - virus” complex has a negative electric charge on the “nanowire - solution phase” interface, the developed recorder is suitable for detecting viral particles. Also, for viral detection necessary about 1000 seconds.

Quick label-free virus screening and highly sensitive analytical tools/techniques are becoming extremely important in a pandemic. In this study, we developed a biosensing device based on the silicon nanoribbon multichannel and dielectrophoretic controlled sensors functionalized with SARS-CoV-2 spike antibodies for the use as a platform for the detection and studding of properties of viruses and their protein components. Replicatively defective viral particles based on vesicular stomatitis viruses and HIV-1 were used as carrier molecules to deliver the target SARS-CoV-2 spike S-proteins to sensory elements. It was shown that fully CMOS-compatible nanoribbon sensors have the subattomolar sensitivity and dynamic range of 4 orders. Specific interaction between S-proteins and antibodies leads to the accumulation of the negative charge on the sensor surface. Nonspecific interactions of the viral particles lead to the positive charge accumulation. It was shown that dielectrophoretic controlled sensors allow to estimate the effective charge of the single virus at the sensor surface and separate it from the charge associated with the binding of target proteins with the sensor surface.

The detection of influenza A virions with a nanoribbon detector (NR detector) has been demonstrated. Chips for the detector have been fabricated based on silicon-on-insulator nanoribbon structures (SOI nanoribbon chip), using a complementary metal-oxide-semiconductor (CMOS)-compatible technology—by means of gas-phase etching and standard optical photolithography. The surface of the SOI nanoribbon chip contains a matrix of 10 nanoribbon (NR) sensor elements. SOI nanoribbon chips of n-type conductance have been used for this study. For biospecific detection of target particles, antibodies against influenza virus have been covalently immobilized onto NRs. Influenza A virus detection was performed by real-time registration of the source-drain current through the NRs. The detection of the target viral particles was carried out in buffer solutions at the target particles concentration within the range from 107 to 103 viral particles per milliliter (VP/mL). The lowest detectable concentration of the target viral particles was 6 × 10−16 M (corresponding to 104 VP/mL). The use of solutions containing ~109 to 1010 VP/mL resulted in saturation of the sensor surface with the target virions. In the saturation mode, detection was impossible.

С помощью метода диэлектрофореза в неоднородном переменном электрическом поле при использовании оптической системы детекции клеток проведено исследование электрических и вязкоупругих параметров эритроцитов в частотном диапазоне от 5·104 до 1·106 MHz у 129 больных с колоректальным раком (КРР) различных стадий развития заболевания, 25 человек с аденоматозными полипами и 35 лиц группы сравнения. Показано, что величины физических характеристик эритроцитов значимо различаются как при сопоставлении групп контроля и пациентов с аденоматозными полипами и больных с ранними стадиями КРР, так и при сравнении пациентов с различными стадиями онкологического процесса между собой. Построение SHAP-графиков на основе электрических и вязкоупругих параметров эритроцитов позволило достичь 100% диагностической точности при различении пациентов с аденоматозными полипами, ранними стадиями КРР от здоровых лиц, 98.7% точности --- при дифференцировании пациентов с полипами от больных с ранними стадиями КРР, 91.9% точности --- при различении ранних и поздних стадий КРР. Полученные результаты демонстрируют высокий потенциал предложенного метода для скрининга и диагностики КРР. Ключевые слова: диэлектрофорез, эритроциты, электрические и вязкоупругие параметры, диагностика, колоректальный рак, аденоматозные полипы, SHAP-графики.

In this study, laboratory preparation of the biosensor based on silicon nanowire field-effect transistors (SiNW-FETs) for virus indication was performed. The authors examined a number of decontamination agents for cleaning the surface of SiNW-FETs using solutions such as hydrogen peroxide, sulfuric acid, hydrofluoric acid, ammonium hydroxide. Biosensor surface functionalization for virus indication was performed through the attachment of antibodies by covalent binding using (3-aminopropyl) triethoxysilane and glutaraldehyde as solutions of cross-linkers. It was determined that a mixture of hydrogen peroxide and water is effective for removing contamination, and (3-aminopropyl) triethoxysilane in ethanol is effective for surface modification.

The aim of this work is to study the features of the electrical and viscoelastic parameters of erythrocytes in patients with inflammatory bowel diseases (ulcerative colitis, Crohn’s disease, unclassified colitis), taking into account the stage of the disease for possible use in differential diagnosis.The electrical and viscoelastic parameters of erythrocytes were studied using dielectrophoresis in 109 patients with IBD, mean age 37,7 + 11,7 years (50 patients with ulcerative colitis (UC), 41 with Crohn’s disease (CD), 18 with unclassified colitis (UCC) and 53 conditionally healthy, comparable in age and sex with the main groups.Red blood cells of individuals with IBD differed from those in the comparison group by a smaller average diameter, an increased proportion of deformed, spherocytic cells with a changed surface character with a reduced ability to deform, a lower level of surface charge of cells, an altered membrane structure with an increased ability to conduct electric current, prone to destruction and the formation of aggregates (p <0,0001–0,05).Analysis in individual groups with IBD in the acute stage, taking into account the therapy, revealed significant differences between the forms of IBD: in patients with Crohn’s disease, in contrast to patients with UC, red blood cells had lower values of the amplitude of deformation, capacity, dipole moment, and velocity of movement of cells towards electrodes, the proportion of discocytes, polarizability at most of the frequencies of the electric field (p <0,00001–0,05). On the contrary, the summarized indicators of rigidity, viscosity, electrical conductivity, aggregation and destruction indices were higher in CD than in UC (p <0,0001–0,05). CD patients had a greater number of deformed cells with altered surface character (p <0,00001).The features of the electrical and viscoelastic parameters of erythrocytes in patients with differentnosological forms of IBD can be used for the differential diagnosis of ulcerative colitis and Crohn’s disease in case of colon lesions, in the long term — for verification of the diagnosis in unclassified colitis.

The results of identifying the vaccinia virus with the use of nanowire biosensors manufactured on the basis of silicon-on-insulator (SOI) films were presented. In our experiments, the vaccinia virus, the LIVP strain from the collection of the State Research Center of Virology and Biotechnology VECTOR of the Federal Service for Surveillance on Consumer Rights Protection and Human Wellbeing, and the rabbit blood serum containing specific polyclonal antibodies to the vaccinia virus were used. As shown by our studies, the polyvalent blood serum was electrically neutral at the sensor surface–viral suspension phase interface, the vaccinia virus was positively charged, and polyvalent blood serum–vaccinia virus vaccine complexes had a negative effective charge.

The recent outbreak of coronavirus disease caused by the respiratory syndrome coronavirus 2 (SARS-CoV-2) has highlighted the urgent need to develop fast and highly sensitive analytical tools and diagnostic devices to detect and study of the fundamental properties viruses and their nucleic acid and protein components [1]. Silicon-on-insulator field-effect transistors (SOI-FETs) based sensors provide the versatile platform for direct detection of biological species as excellent electrical signal converters. These devices have demonstrated applications for label-free, ultra-sensitive, and selective real-time detection of a wide range of biological species, including nucleic acids, proteins and viruses in either single-element or multiplexed formats [2-5]. Dielectrophoresis (DEP) and electro-hydrodynamic techniques are well known as the methods of selection and delivery of analytes to overcome limitations of diffusive transport to sensor elements without additional processing or labeling steps [6]. The aim of this study was to investigate the features of the behavior of the viruses when they are indicated by SOI-FET sensors with DEF-control. For this, SOI-FET sensors with lateral DEP-electrodes and multichannel sensors, for comparison, were used. Top-down technology with using optical lithography was applied for sensor fabrication. Devices manufacturing details are described elsewhere [3]. As an analyte, we used nuclear polyhedrosis viruses (NPVs), coronavirus virus-like particles (CVP) and suspension of specific antibodies to the virus created in the Federal research center of Virology and biotechnology "Vector" of Rospotrebnadzor. The results showed that the sensors used in the study provide the subatomolar level of virus detection. DEP-concentration of viruses increase the response of the sensors by factors of 2 to 9 (compared to the response of sensors without DEP control) and allows the false positives can be eliminated. NPVs lose their mobility with prolonged exposure to an alternating field in the sub-MHz range. The DEP-concentration of CVP leads to the formation of crystal-like structures (Fig.1). This study was supported by grant no. 18-29-02091 of the Russian Foundation for Basic Research. Sample preparation of biological materials was done within the framework of the State Task of Rospotrebnadzor. Referencies: WHO Director-General's opening remarks at the media briefing on COVID-19 – 23 April 2021 23 апреля 2021 г.https://www.who.int/director-general/speeches/detail/who-director-general-s-opening-remarks-at-the-media-briefing-on-covid-19-23-april-2021. Patolsky F., Zheng G., Hayden O., Lakadamyali M., Zhuang X., Lieber C. M. Electrical detection of single viruses // Proc. Natl. Acad. Sci. 2004, v. 101. p. 14017-14022. O. V. Naumova, V. M. Generalov, E. G. Zaitseva, A. V. Latyshev, A. L. Aseev, S. A. Pyankov, I. V. Kolosov, G. G. Ananko, A. P. Agafonov, E. V. Gavrilova, R. A. Maksyutov, and A. S. Safatov. Biosensors Based on Soi Nanowire Transistors for Biomedicine and Virusology. Russian Microelectronics, 2021, v. 50, N3, p. 137–145. Ivanov Y.D., Pleshakova T.O., Kozlov A.F., Malsagova K.A., Krohin N.V., Shumyantseva V.V., Shumov I.D., Popov V.P., Naumova O.V., Fomin B.I., Nasimov D.A., Aseev A.L., Archakov A.I. SOI nanowire for the high-sensitive detection of HBsAg and a-fetoprotein. Lab Chip. 2012, v. 12, p. 5104-5111. Dmitrienko E., Naumova O., Fomin B., Kupryushkin M., Volkova A., Amirkhanov N., Semenov D., Pyshnaya I., Pyshnyi D. Surface modification of SOI FET sensors for label-free and specific detection of short RNA analyte. Nanomedicine 2016, v. 11, N 16, p. 2073-2082. Lee S., Roh S.M., Lee E., Park Y., Lee B.C., Kwon Y., Kim H.J., Kim J. Applications of converged various forces for detection of biomolecules and novelty of dielectrophoretic force in the applications(Review). Sensors, 2020, v.20, p.3242. Fig.1 – Optical image of sensor with lateral DEP electrodes after CVP detection. In the left - CVP organized in crystal-like structures under DEP-concentration, in the right (green dots on dark field) - viruses with luminescent labels. S - source, D - drain. G1, G2 - lateral DEP electrodes. Figure 1

The aim of this work is to study the electrical and viscoelastic parameters of erythrocytes for patients with inflammatory bowel diseases (IBD), examined in dynamics, as possible predictors of exacerbation of the disease. Material and methods. In dynamics, 23 patients with IBD (37.9 ± 4.3 years) were examined. The first examination was carried out in the stage of exacerbation, the second – after 6–12 months – in the stage of remission of IBD. Additionally, 36 patients with IBD in remission were examined to assess the predictive capabilities of erythrocyte parameters with subsequent monitoring of their condition for 6–12 months. The electrical and viscoelastic parameters of erythrocytes were investigated by dielectrophoresis. Statistical processing was carried out using a system of machine learning methods – Random Forest, MATLAB (R2019a, MathWorks). Results and discussion. The parameters of erythrocytes, which are predictors of exacerbation of IBD, were revealed: an increase in the proportion of deformed cells (p = 0.0001); altered nature of the erythrocyte surface (p = 0.011); increased electrical conductivity of membranes (p = 0.0019); reduced dipole moment (p = 0.0015), the rate of directional movement of erythrocytes to the electrodes (p = 0.005) (paired and unpaired Volcano plot methods), reduced deformation amplitude at a frequency of 5×105 Hz (p = 0.009), capacity of erythrocyte membranes (p = 0.029 ) (unpaired Volcano plot method). Indicators associated with changes in the charge of cells, the structure of erythrocyte membranes and the level of energy metabolism of the cell turned out to be significant. A high diagnostic accuracy of these indicators was established as predictors: the proportion of deformed cells (AUC 0.939), a summarized viscosity index (AUC 0.932). Cluster analysis of the values of erythrocyte parameters – predictors of exacerbation made it possible to stratify the risk of exacerbation: at the most altered levels of parameters – the development of exacerbation after 2.5–4.5 months, intermediate levels – after 4–6 months, minimally changed – after 8–12 months (predictive accuracy – 92 %). Conclusions. The revealed electrical and viscoelastic parameters of erythrocytes should be considered as promising predictors of exacerbation in patients with IBD.

This article contains the results of research on the topical problem of highly sensitive express registration of biological objects using field-effect transistors with the surface open for analyte access, which are made based on silicon-on-insulator (SOI) films. The possibilities of dielectrophoretic effects for controlling the concentration of the analyte in the area of sensory elements are considered on the example of the indication of viruses of nuclear polyhedrosis and vaccinia. It is shown that the use of the dielectrophoresis (DEPh) effect makes it possible to solve (1) the key tasks for creating sensor systems: increasing the detecting ability, as well as exrtacting and verifying the signal from the target particles; and (2) the fundamental task: determining the charge state of the analyte in solutions without modifying the sensors’ surface. The problems and prospects of the mass application of nanowire (NW) biosensors, including those with the dielectrophoretic effect, in biotechnology, virology, etc., are discussed.

Abstract The purpose is to identify the pathophysiological mechanisms of stroke development in patients with COVID-19. Methods A total of 92 patients (46.72+1.72 years) with impairments of cerebral circulation due to COVID-19 (confirmed by positive PCR test results) had been examined. Among them, 67 patients had an ischemic stroke, 14–a transient ischaemic attack, 11–an intracerebral hemorrhage, 3– a subarachnoid hemorrhage. The parameters of hemostasis were measured by standard methods, electrical and viscoelastic parameters of red blood cells (RBC) by the dielectrophoresis method was carried out. Results Most of the surveyed persons (60 patients) showed signs of an intravascular coagulation and thrombosis: accelerated platelet-leukocyte aggregation, increased levels of coagulation products, reduced fibrinolysis activity (p=0.002–0.04). The levels of D-dimer, fibrinogen, ESR, platelet count were significantly higher in this group compared to patients in the second one (p<0.01). A moderate increase in summarized rigidity, viscosity of RBC was noted. The level of RBC hemolysis was associated with platelet count (r=0.727, p<0.05), D-dimer level (r=0.422, p=0.04), and fibrinogen level (r=0.318, p<0.05). In the second group of patients (32 persons with a predominance of men - 25 male subjects), the markers of thrombosis had moderate deviations. A sharply reduced RBC deformability with increased summarized rigidity and viscosity was dominant coupled with the background of high electrical conductivity of cell membranes compared to the indicators in the first group (p<0.01). There was a decrease in membrane capacity, surface charge, electrical dipole moment of the cells and polarizability at all frequencies of the electric field than those in the first group (p=0.0001–0.05). A sharp decrease in RBC deformability creates obstacles to overcoming small-diameter capillaries, leading to violations of microcirculatory blood flow. The RBC deformability was associated with levels of ferritin (r=0.407, p=0.024), HbA1c (r=0.419, p=0.033), uric acid (r=−0.303, p<0.05), and LDL cholesterol (r=0.426, p=0.029). Incubation of blood samples in vitro for 10 min with riboflavin, nicotinamide, inosine, which ensures RBC energy metabolism (anaerobic glycolysis and pentose phosphate pathway) restored the reduced the RBC deformability (p<0.01), and decreased the RBC aggregation (p<0.001). Similar changes were obtained when coenzymes were administered to patients in vivo. Conclusion Two independent mechanisms of cerebral circulatory disturbances have been identified in COVID-19 stroke patients: both thrombotic and hemorheologic. The thrombotic variant is associated with a procoagulant state and with an activity of inflammation. The hemorheologic variant is caused by a decrease in the activity of the RBC energy metabolism enzymes; it is associated with the presence of metabolic disorders and is to be eliminated by an administration of coenzymes and metabolites. Funding Acknowledgement Type of funding sources: Other. Main funding source(s): This research was done within the framework of the topic “Epidemiological monitoring of the population state of health and studies on molecular genetic and molecular biological mechanisms of the development of common internal diseases in Siberia for improvement of the relevant diagnostic, preventive, and therapeutic methods” in State Assignment No. 0324-2018-0001, registration No. AAAA-A17-117112850280-2

Работа посвящена исследованию распределения потенциалов в системах сенсор - электролит с управлением концентрацией аналита переменным электрическим полем и исследованию особенностей поведения аналита в таких устройствах.

The research aim is to study the associations of changes in the content of hemoglobin complexes by the Raman spectroscopy with electrical and viscoelastic parameters of erythrocytes (using the dielectrophoresis method) among patients with arterial hypertension (AH) (including resistant AH), to evaluate the possibility of using these parameters for diagnostic purposes. Fifty males (54 ± 6 years) with stage 2 of AH have been examined, 24 of them have showed resistant AH. We have determined a significant decrease in the level of hemoglobin-ligand complexes, Hb-NO (II) complexes in patients with resistant AH compared to those among patients with controlled AH and among healthy patients (p < 0.001 – 0.05). We have found correlations between intensities of the most important signals of hemoglobin Raman spectra (1325, 1350, 1550, 1580, 1660, 1668 cm –1 ) and electric and viscoelastic parameters of erythrocytes (amplitude of erythrocytes deformation, summarized indicators of viscosity and rigidity, the magnitude of the dipole moment, polarizability at the frequency 106 Hz, electrical conductivity, index of destruction), the intensity of which had been the biggest one for resistant AH. It has been shown that the combined use of two methods (Raman spectroscopy of hemoglobin and electrical and the studies of erythrocytes by the dielectrophoresis method) allowed to increase the diagnostic accuracy to detect the resistant arterial hypertension up to 88%, sensitivity up to 84.6%, specificity up to 91.7% compared to the data of the combined clinical and instrumental methods of research. The capability of this combination approach exceeds the capabilities of the methods separately.