This PDF file contains the front matter associated with SPIE Proceedings Volume 12194, including the Title Page, Copyright information, Table of Contents, and Conference Committee listings.

Our study demonstrates the potential of Flicker-Noise Spectroscopy analysis of neuromagnetic brain responses (magnetoencephalograms) in possible diagnosis and estimating the effectiveness of treatment of photosensitive epilepsy. The tendency of the organism to restore the synchronization to its normal levels is considered the cornerstone of the analysis. A two-parameter Flicker-Noise Spectroscopy cross-correlation function is applied to show that the breakdown of frequency-phase synchronization in the magnetoencephalograms of the patient can be associated with two distinct mechanisms: high-frequency resonances (50-100 Hz) at specific brain areas and changes in high-frequency stochastic components for other brain areas. Our analysis also reveals a certain disruption of regular behavior and occurrence of asymmetry in three-dimensional plots of the cross-correlation function for some healthy controls, suggesting that these individuals may be susceptible to photosensitive epilepsy. We believe that a similar cross-correlation analysis based on appropriate biomedical signals may be used to assess the effectiveness of medical treatment for other diseases and conditions.

This work aims to show that the radioengineering generators able to demonstrate neural like activity can switch to the epileptiform behavior due to short time external driving if coupled using sigmoid function. The effect takes place for various number of generators in ensemble. The particular coupling architecture and initial phase of external driving are of importance.

We present a detailed description of the numerical implementation (for either MATLAB or GNU Octave) of a novel method for processing data with serial localized peaks intended to distinguish between individual components even when they form a mono-modal but complicatedly shaped structure [E.B. Postnikov et al. Mathematics 9 (2021) 2802]. The essence of the method consists of a cascade of local non-linear approximations by the Gaussian function at the vicinity of the zero-crossings for the signal’s Hilbert transform. At the first level, this procedure is applied to the processed signal directly; at the next level, it is applied to residuals between the signal and approximations on the previous levels. As a practical example, we consider the decomposition of Raman spectra recorded from different strains of Mycobacterium tuberculosis. Finally, we discuss other areas of applicability for the proposed method of signal processing.

Epilepsy is a neurological disease that leads its patients to suffer from seizures, which condition their behavior and lifestyle. Neurologists use an electroencephalogram (EEG) to diagnose this disease. This method of recording cerebral brain activity illustrates the signaling behavior of a person's brain, allowing, among other things, the diagnosis of epilepsy. In the presented study we investigate the possible applications of cross-correlation analysis in the framework of Memory Functions Formalism for the diagnosis of nocturnal frontal lobe epilepsy (NFLE). During the analysis we study statistical memory effects in bioelectric brain activity of 8 healthy subjects and 19 patients with NFLE. Furthermore, we discover different nature of the spectral behavior of EEG signals as well as the difference in the level of manifestation of the frequency-phase synchronization effects for the control group and the group of patients with epilepsy. Finally, we show that the application of the statistical analysis methodology of cross-correlations in bioelectrical brain cortex activity recordings, after additional verification, can be helpful in the problem of searching for diagnostic criteria of nocturnal frontal lobe epilepsy.

Photoplethysmography is an important optical method in healthcare and contains a wealth of information about physiological dynamics. For a quantitative assessment of vascular tone indices, an effective and modern method of analyzing the relief of the photoplethysmogram within the pulse cycle is required. A new method for detecting singular points of the contour of photoplethysmograms is proposed, based on the model of a multilayer perceptron neural network (MLPNN). The successful work of the network of the method for finding the systolic peak, dicrotic notch and diastolic peak has been demonstrated. It is shown that the average relative error does not exceed 5 percent. The proposed method can be used in computer monitoring systems for vascular tone.

Neuromorphic technologies are among the most actual interdisciplinary fields of science. Neuromorphic devices are developing to implement principles and algorithms of brain information processing in computational systems. Neuromorphic devices require development of electronic components: neurons and synapses. The excitability of the neuron-like generator based on phase-locked loop is studied under external pulse stimulation. Imitational modelling study of electronic neuron-like generator model with excitable and self-oscillating modes have conducted in Simulink environment. Spiking and bursting self-oscillating modes known from numerical simulations were observed. Novel excitable dynamics was studied in presence of external pulse stimulation.

The work aims to study the features of autonomic control of the cardiovascular system in two groups of patients with Covid-19: with and without arterial hypertension. A total of 15 pairs of 20-minute electrocardiogram and photoplethysmogram signals were registrated in each group. We used the methods of spectral analysis, as well as the previously proposed method for assessing the phase synchronization of 0.1-Hz rhythms of signals of autonomic control of heart rate and blood pressure. The data of patients with chronic arterial hypertension showed a lower level of synchronization than patients without it. This is probably due to the peculiarities of autonomic control of the cardiovascular system in patients with chronic arterial hypertension.

Astrocytes not only provide for the transfer of nutrients between blood vessels and neurons, but also take part in signaling through nerve tissue and regulate formation, pruning, and plasticity of synapses. Analysis of the impact of the astrocytic domain organization on the local and collective dynamics of neurons is needed for both the fundamental understanding of the mechanisms underlying cognition and for the creation of new methods of neurodegenerative pathology treatment targeted at non-neuronal cells without direct effects on the neural network. Based on the available experimental data, we propose a model study of the role of astrocytic calcium signaling in the regulation of synaptic transmission between neurons in order to elucidate the role played by astrocyte calcium signaling in signaling pathways regulating neural activity. The proposed model is based on the following assumptions: (i) localized release of gliotransmitters depends on the spatiotemporal patterns of calcium activity and is determined by cell morphology and topology of the entire network; (ii) the release of gliotransmitters can lead to spatial segregation of the nervous tissue into regions in which different conditions are maintained, favoring for increased or decreased synaptic efficacy.

We study the effect of introducing localized synapses on the astrocyte calcium activity. Instead of homogeneous excitation we include in the model well-defined synapses as sources of glutamate. Synaptic density was scaled according to the astrocyte morphology, in particular, surface-volume ratio in accordance with experimental data. Unlike uniform excitation model, where the calcium activity was dependent only on the astrocyte morphology, different localization of synapses causes the change in baseline calcium distribution. Localization of synapses leads to the decrease of baseline calcium levels in the peripheral regions of the astrocyte, while the dynamics of thick branches and soma does not change significantly. Introduction of synapses also affects the distribution of baseline calcium levels based on AVF parameter. Supposedly, this indicates the emergence of “microdomains” - regions of the astrocyte with the highest average activity.

Known works have shown a decrease in the coherence of the process of parasympathetic control of heart rate variability and the process of respiration during healthy aging. To get an idea of the reasons for the decrease in the coherence of the processes under study, in this work we investigated the possibility of using the method for assessing the directional coupling based on modeling of phase dynamics to analyze the directional couplings between the processes of parasympathetic control of heart rate variability and the respiration process. Due to the complexity, nonstationarity and strong nonlinearity of the processes under study, an important and nontrivial task is to choose the duration of the analyzed time series of high-frequency oscillations of the RR-intervals signal and respiration in calculating the indices of directional coupling. This work shows the possibility of using the method for assessing the directional coupling with the length of the analyzed time series from 15 to 450 characteristic periods of oscillations.

The paper deals with processing data obtained using nailfold high-speed videocapillaroscopy. To detect the red blood cells velocity two approaches are used. The deterministic approach is based on pixel intensities analysis for object detection and calculation of the displacement and velocity of red blood cells in a capillary. The obtained data formulate targets for the second approach. The stochastic approach is based on a sequence of artificial neural networks. The semantic segmentation network UNet is used for capillary detection. Then, the classification network GoogLeNet or ResNet is used as a feature extractor to convert masked video frames to a sequence of feature vectors. And finally, the long short-term memory network is used to approximate the red blood cells velocity. The results demonstrated that the accuracy of the mean velocity approximation in the time range of several seconds is up to 0.96. But the accuracy at each specific time moment is less accurate. So, the proposed algorithm allows the determination of the RBCs mean velocity but it doesn't allow determination of the RBCs pulsations accurate enough.

The aim of this work is to develop practical tools to recognize the average flow rate of physiological fluids in capillaries. This tool is represented by classification models in an artificial neural networks form. The flow rate data were obtained experimentally. Intralipid was used as the test liquid. Laser speckle contrast imaging was used to obtain images of liquid flow in a glass capillary. The experiment was carried out with an average flow rate of 0-2 mm/s with various concentrations of intralipid. The results of training of fully connected and convolutional neural networks for processing the received data are presented. The accuracy of determining the average flow rate of intralipid with different concentrations was comparable to the previously obtained results for a fixed concentration and amounted to approximately 97.5%.

Maintaining an equilibrium of the human body in an upright position is crucial for the majority of motor activities. Numerous studies of physiologists, clinicians, scientific researchers show that the equilibrium function is very complex. In this work, we conducted an experiment involving equilibrium maintaining on a balance board to research different aspects of this process. The purpose of this study was to assess the dynamics of the movement of the platform movement associated with the equilibrium during the experiment and how muscle fatigue effects it. With the help of the statistical analysis we determine which muscles were affected by the fatigue more.

Crowdion presents an interstitial mobile defect propagating in close-packed crystallographic directions and plays an important role in energy and mass transfer processes occurring in bcc tungsten lattice in non-equilibrium conditions. In the present day, tungsten remains one of the most promising plasma-oriented material, which saves its protective features even under high-intensive irradiation influence in nuclear reactors. Crowdions can be one of most possible and effective nonlinear channels of energy dissipation obtaining under irradiation. The dynamics of the crowdion in the lattice with the zero or very low temperature has been already deeply studied. At the same time, influence of thermal oscillations of atoms on the crowdion dynamics has not been studied in detail, despite the processes of irradiation always occur under finite nonzero temperature. In the present work, we try to reveal changing the crowdion features under different finite temperature of the tungsten lattice.

Crowdion as one of types of an interstitial mobile defect propagating in close-packed crystallographic directions can play an important role in relaxation processes occurring in bcc lattices of tungsten in nonequilibrium conditions. The crowdions is an effectively transport of mass and energy in the metal. Tungsten is considered one of the best options as a plasma-oriented material which can be exposed to ion irradiation in nuclear reactors. Recently dynamics of crowdions has been extensively studied for different types of lattices and dimensions. However, the point of energy exchange between crowdions has not been considered earlier. The paper presents an analysis of energy exchange in a complex of crowdions located in neighboring closely packed atomic row. Obtained results reveal that closely located crowdions can intensively transfer energy from one to another thus affecting the dynamics and scenario of defect structure evolution in the crystal. It is known that irradiation of tungsten can lead to microstructural changes, such as bubbles, pores and another types of defects. Moreover, the metal constantly at these conditions are heated up to extremely high temperature. Apparently, the crowdions play an important role in the formation of different defects inside the tungsten. And aim of this work is a numerically analysis of features of the crowdion in this highly heated metal bcc lattice.

We propose a mathematical model for the multifractal dynamics of COVID-19 pandemic. Within this model and the finite-difference parametric nonlinear equations of the reduced SIR (Susceptible-Infected-Removed) model we calculate the fractal dimensions of various segments of daily disease incidence in the world and the variations of COVID-19 basic reproduction number based on the COVID-19 World Statistics data.

In this paper, we investigated the fatigue-related processes of reconfiguring the human brain functional network while solving the cognitive task. We analyzed the correlations between the psychophysiological state of the subject with the characteristics of neural activity. We found that the subject’s fatigue positively correlates with the average degree of functional connectivities between neural ensembles in the beta and alpha frequency ranges. The obtained results indicate the increase in the integrative processes of a functional neural network. We revealed that the increasing fatigue during the experiment does not decrease the efficiency of the task completion: the speed and correctness of responses do not change. This suggests that functional integration may reflect the optimization of the brain’s neural network during the experiment.

In this paper, we demonstrate the use of an approach to quantifying vibrational patterns on electroencephalo- grams (EEG) of healthy adult patients. Our study involved volunteers from among the patients of the University Clinical Hospital named after S.R. Peacemakers (Saratov, Russian Federation) who underwent polysomnographic study. Mathematical processing of EEG data was carried out over the entire recording of nocturnal sleep without dividing into stages. We evaluated two parameters of oscillatory patterns - their duration and number in a sliding time window with a duration of 5 seconds.

We consider a network of networks consisting of small input neural network and four small-world subnetworks Hodgkin-Huxley neurons. Input network receives an external signal and transfers it to subnetworks via excitatory couplings while the subnets interact with each other via inhibitory couplings. We show that the subnets are divided into 2 clusters under the influence of an inhibitory couplings between them. The synchronization indexes of subnetworks periodically change in time. We found that SIs can oscillate either in-phase or anti-phase depending on the couplings between subnetworks.

In this paper, we present an analysis of the dynamics of functional connectivity of the cerebral cortical network using near-infrared spectroscopy during human solutions to simple cognitive tasks. A task-based on the Sternberg paradigm was chosen to provide a cognitive load. We identified statistically significant changes in the communication forces obtained on the basis of the analysis of oxyhemoglobin signals during the experiment. We found that in the course of the experiment, there is a restructuring of the functional network, which is accompanied by a decrease in the average connectivity strength between the cortical areas under study. We showed that there is a correlation between the subjective evaluation of fatigue degree and the characteristics of the identified functional neural network.

In this work we present the development process of a wireless portable module. It is developed to record various characteristics during sport shooting, such as automatic detection of the moment of shot and barrel movement during aiming, taking into account the peculiarities of its use in neurophysiological research. We propose an approach allowing to synchronize devices in a wireless local network with high accuracy (synchronization accuracy was 2 ms), as well as a method of logging the recorded data at a sampling rate of up to 2 kHz on an onboard flash drive.

In this study, we analyzed the effect of the ambiguity of the previous visual stimulus on the response time taken to process the current visual stimulus. Our experimental paradigm included the repeated presentation of ambiguous Necker cubes images with varying degrees of ambiguity. We studied the response time and the time-frequency features of EEG signals, reflecting the influence of the “sensory prehistory” on the current stimulus processing.

In this study, we analyzed the behavioral characteristics of the subjects (response time to visual stimuli and the correctness of interpretation), as well as brain activity at the sensory level when classifying repeatedly presented ambiguous images. We showed that the reaction time decreased for both LA and HA stimuli with the task completion time. In addition, the distribution of perception errors decreased for HA stimuli, but not for LA stimuli. At the sensory level, we found an increase in EEG power in the frequency range of 9-11 Hz with an increase in the task execution time.

The design of visual decision-making task with uncertainty was proposed. Set of experiments was conducted in accordance with this design and obtained EEG dataset was analyzed. Analysis of EEG characteristics in time, frequency and space domains allowed to introduce certain features that can be used to separate right and wrong outcomes in the task prior actual subject's response.

Recurrence quantification analysis was applied to detect the P300 potential on single-trial EEG. We demonstrated that the emergence of P300 as a result of a response to a stimulus is associated with the brain activity complexity increase. The measures of recurrence quantification analysis have sufficient sensitivity to detect these changes even on the single time series.

When creating motor imagery brain-computer interfaces (BCI), there is a problem with the accuracy of determining which limb made the movement. The accuracy of the classifiers is no more than 80-85%. In this work, we examined this problem from the point of view of the well-known phenomenon of lateralization during motor movements. Several different algrorithms were used to investigate proportion of contralateralization and ipsilateralization based on event related desynchronization/synchronization (ERD/ERS) calculations using EEG data gathered throughout motor function related experiment.

Based on the results of the EEG experiment in the process of human motor execution, we performed in this paper a source-level analysis of brain activity during the motor initiation phase for two age groups: young and elderly adults. In the theta frequency band, we discovered stronger activation of the contralateral area of the primary motor cortex (Postcentral L and Precentral L zones) for elderly subjects compared to young ones in the right (dominant) hand movements. We discuss the correlation of the obtained source-level results with the known age-related slowing down in the motor initiation before the dominant hand movements. The obtained results are essential for explaining age-related changes in behavioral characteristics, such as reaction time, the accuracy of motor performance, etc.

The efficiency of silicon nanoparticles (SiNPs) formation via picosecond laser fragmentation of silicon micropowder in water suspension was analyzed. We carried out numerical simulations of propagation of a single focused laser pulse with energy of 16 mJ in suspensions of silicon microparticles (SiMPs) with diameter of 5 μm accounting for temperaturedependent thermal and optical properties of the media under study. The simulations were performed for SiMP mass concentrations varied from 0.5 to 12 mg/mL and irradiation wavelengths of 1064 and 532 nm. To estimate the efficiency of the fragmentation process we calculated the mass of the silicon melted by the laser pulse. The fragmentation process as well as mass of silicon undergone phase transitions were demonstrated to depend significantly on SiMPs mass concentration and wavelength of the laser radiation. For irradiation at 1064 nm the mass of melted silicon varies nonmonotonically with increase of SiMPs mass concentration decreasing to minimum at 5 mg/mL and increasing an order of magnitude with a further increase in SiMPs mass concentration. When using radiation at a wavelength of 532 nm, the mass of melted silicon increases up to two orders of magnitude in comparison with the case of 1064 nm, while the mass of melted silicon rose with increase of the SIMP concentration.

Currently, one of the key challenges in many different fields of science and engineering is the development of methods capable of distinguishing noise signals from chaotic ones. Analysis of the nature and structure of temporal data series can predict many adverse events before they occur: heart or epileptic attacks, various engine breakdowns, changes in financial markets, etc. The problem of distinguishing between signals of random nature (noise signals) and signals whose nature is determined by complex non-periodic (chaotic) dynamics, is not yet completely solved. This work was aimed to create a method of time series analysis based on forbidden permutations patterns, which will be able to distinguish the appearance of atypical dynamics. Preliminary results demonstrate the ability forbidden permutations patterns analysis method to distinguish between chaotic and noisy dynamics.

Surface-enhanced Raman scattering (SERS) tags have proven to be excellent labels for tissue bioimaging because of their low interference from biological matrices, high photostability, and possibility to use as theranostic agent. Although SERS tags are widely used for imaging of tumors in vivo, in practice, low contrast of the tags accumulation in the tissue and strong light scattering can significantly affect their detectability. In this work, we studied these effects by using a phantom of tumor tissue with incorporated SERS tags. To simulate surrounding medium with different turbidity, the phantom was placed in a 4 mm thick agarose gel containing intralipid at a concentration of 0-1%. We found that shielding the phantom with a turbid medium leads not only to a decrease in delectability but also to a decrease in the apparent size of the imaging object. For in vivo experiments we used an optical clearing technique to improve the SERS signal from a subcutaneous tumor phantom. The use of optical clearing increases the SERS signal target-to-background ratio for 5 times and allow to decrease the total imaging time for at least 10 times. In addition, SERS imaging assisted with optical clearing made it possible to more precisely determine the shape and boundaries of the implanted phantom.

Gold nanoantennas are a new type of nanostars with long spikes and small cores and the ability to adjust localized surface plasmon resonance in the range from 600 to 1600 nm by changing the shape and size of nanoparticles. In this work, the morphometric and optical properties of gold nanoantennas are investigated depending on the concentration of gold seeds and hydrochloric acid. Transmission electron microscopy (TEM) reveals a decrease in the spike length and the core diameter of nanoantennas under an increase in the seed concentration. The reaction rate decreases after the addition of hydrochloric acid. With a minimal addition of hydrochloric acid, the length of the spikes increases. However, with an increase in the hydrochloric acid concentration, the length of the spikes decreases. Increasing the concentration of both seeds and hydrochloric acid leads to a shift of the plasmon resonance towards shorter wavelengths. The cell viability test showed negligible in vitro citotoxicity of nanoantennas for two cell lines.

In this paper, we report on water synthesis with a selective size of AgInS/ZnS quantum dots (QDs) coated with thioglycolic acid and on the analysis of their colloidal stability in water and physiological saline buffers to assess their potential use as a fluorescent label in bioanalysis. Nine fractions of AgInS/ZnS hydrophilic QDs were dispersed in buffer solutions with a wide pH range (3.5–9.5) and investigated by measuring the fluorescence intensity and zeta potential. The results demonstrate the possibility of using water-soluble thioglycolic acid-coated QDs as a surface ligand for immunofluorescent labeling using commonly used buffers. The highest QD stability was observed in the pH range (6.0- 9.5).

A complex of gold nanoparticles with silymarin, a flavonoid-type hepatoprotector isolated from the fruits of milk thistle (Silybum marianum L. Gaertn), was obtained by the method of green synthesis. The resulting conjugate was used to immunize rabbits. After the completion of immunization, the isolated serum immunoglobulins were additionally purified using the method of high performance liquid chromatography. Purified anti-silymarin IgGs were tested for specific antigen binding by dot immunoassay. The detection limit for silymarin was 12.5 ng. The obtained antibodies were labeled with TRITC and used to study the penetration of silymarin into the cells of the reticuloendothelial system by immunofluorescence microscopy. It was demonstrated that silymarin conjugated with gold nanoparticles penetrated into peritoneal macrophages much more efficiently as compared to the native preparation. The results obtained can serve as a basis for creating a new dosage form of silymarin in the form of its conjugate with gold nanoparticles, which enhances hepatoprotective properties due to better penetration of the drug into the cells of the reticuloendothelial system.

Here we report the construction, results of testing, and methodology of data processing for a newly developed portable microbiological analyzer (patent application RU2021111818,24.04.2021). This Arduino-based setup allows for high-frequency temporal resolution of data recordings that reduces instant noises and provides detailed dynamical curves. It was tested with the culture of baker’s yeast Saccharomyces cerevisiae in a liquid medium with the usage of resazurin as a redox indicator changing its colour. Moreover, for such fast-growing culture, one should take into account the full chain of chemical transitions from resazurin to resarufin and further to dihydroresorufin. We argue that the respective model of such chemical cascade can be treated with the logletdecomposition of the recorded data into components of two Bertalanffy’s models and demonstrate the ability to define the required kinetic rates.

In recent years, there have been a lot of papers and reports on the DNA-templated silver nanoclusters. These nanoclusters are ultra-bright and stable fluorescent beacons. Application of DNA-templated silver nanoclusters for biomolecules detection and bioimaging seems promising. However, direct conjugation between DNA-templated silver nanoclusters and antibodies is complicated while nanoclusters tend to degrade under conjugation conditions. To overcome this problem, it is possible to create a probe that not only can serve as an fluorescence reporter but also can contain the recognition motif that could selectively bind with target biomolecules. In the present work, we developed DNA-templated silver nanoclusters based on aptamer to lung cancer. Various sequences were added to core aptamer nucleotide sequence to form fluorescent nanoclusters. The synthesis of DNA-templated silver nanoclusters using borohydride reduction was conducted. Nanoclusters with 567 nm excitation and 630 nm emission were produced. The fluorescence quantum yield was 32 %. The storage technique of DNA-templated silver nanoclusters was optimized to ensure their photostability during the storage. Thus, bright and stable fluorescent red-emitting DNA-templated silver nanoclusters based on novel aptamer to lung cancer were developed. However, the potential use of DNA Ag NC for cell staining is complicated by the partial quenching of DNA Ag NC fluorescence in the presence of biomolecules.

Study of energy transfer processes between the rare earth ions in NaGdF₄ nanoparticles tri-doped with rare earth ions Yb³⁺, Er³⁺ and Ho³⁺ or Tm³⁺ was carried out. The luminescence spectra in short-wave infrared and visible ranges were investigated. It was shown that Er³⁺ → Ho³⁺ energy transfer leads to Ho³⁺ luminescence increase. Both Er³⁺ and Ho³⁺ luminescence peaks were observed in short-wave infrared range. For Er³⁺ and Tm3+ co-doped nanoparticles it was hard to separate luminescence peaks in SWIR. However, both Er³⁺ and Tm³⁺ luminescence peaks were observed in visible range. We attribute this effects to Tm³⁺ → Er³⁺ energy transfer which occurs due to overlap of Er³⁺ and Tm³⁺ luminescence bands in short-wave infrared range which leads to Tm³⁺ luminescence decrease. This hypothesis was confirmed by study of β-NaGdF₄ tri-doped with Yb³⁺, Er³⁺ and Tm³⁺ luminescence spectra during heating. The intensity of Tm³⁺ luminescence increased during heating due to non-resonant nature of Yb³⁺ →Tm³⁺ energy transfer and the shape of spectra changed.

Polycyclic aromatic hydrocarbons (PAHs) are known ecotoxicants, the content of which in environmental objects requires constant monitoring. The development of new and improvement of existing methods for the analysis of PAHs is urgent. Luminescent methods are promising for these purposes, in particular, the solid-surface luminescence (SSL) method. In order to improve the analytical characteristics of the determination of PAHs by the SSL method, it is of considerable interest to study the possibilities of combining micellar and sorption concentration with the analysis of PAHs directly in the sorbent phase. The work is devoted to the development of a highly sensitive luminescent sensor system for the determination of PAHs using pyrene as an example by selecting the most effective matrix (cellulose, viscose, polypropylene and polyester) for sorption and observation of SSL, as well as modifying agents - surfactants: anionic - sodium dodecyl sulfate, cationic - cetyltrimethylammonium bromide and nonionic - Triton X-100. The maximum signal of TPL pyrene is observed on a viscose matrix when using a water-micellar solution of Triton X-100. The results obtained can be used to develop a highly sensitive method for monitoring the PAH content in various media.

Our workgroup has recently developed a SPIM-based flow cytometer to detect fluorescent-labeled objects in whole blood [1]. It was used to visualize, detect, and magnetically separate fluorescent-labeled objects without hydrodynamic focusing. The flow cell holder, the magnet shifting system, and the camera filters system of the developed flow cytometer were printed on a standard FDM 3D printer. Here we have modified the optical system by a prism with a printed mounting system to minimize images' parasitic reflections and coma effect. We have also modified the magnetic concentrator system to make magnetic field distribution more efficient for magnetic separation and use a smaller permanent magnet in the system, thus adding whitelight source placement for the separation flow cell.

The object of the study was an aqueous dispersion of gold nanoparticles stabilized with polyvinyl alcohol (AuPVA). It was previously found that AuPVA is characterized by a broad spectrum of antimicrobial activity against standard and clinical strains of gram-positive and gram-negative bacteria and yeasts. The safety of using AuPVA is associated with the absence of toxic effects of its working concentrations on biotest objects and cell cultures. Evaluation of the effectiveness of photodynamic antimicrobial therapy was carried out on a model of experimental full-sleep purulent wounds, which were formed in the interscapular region in rats. We used a semiconductor laser with a wavelength of 405 nm (manufactured by AlcomMedica, St. Petersburg). It was found that the use of 1% aqueous dispersion of AuPVA as a photosensitizer led to a 1,6-fold reduction in the wound healing time compared to the control.

In the present work, using the method of frequency patterns based on the use of continuous wavelet transform, it was shown that after minor orthodontic interventions, changes in the electrical activity of the brain are observed in patients during the passage of a simple cognitive test. At the same time, in a number of channels of the electroencephalogram, there is a change in the number and average lifetime of frequency patterns, while in other channels these changes are not observed.

The enzyme immunoassay (EIA) is one of the most sensitive methods for the detection of molecules (antigens) based on the use of specific antibodies and linked enzymes. In our opinion, the use of gold nanoparticles (AuNP) functionalized simultaneously by two types of protein molecules (antibody and enzyme) is a very promising direction in the development of EIA. The preparation of such bifunctional particles is simpler than chemical conjugations of two types of proteins, and the use is more efficient in comparison with standard antibody–AuNP conjugates. This work aimed to obtain stable AuNPs functionalized horseradish peroxidase (HRP) and antibodies against a bacterial O-antigen. At the first stage, the “golden number” for AuNPs and HRP solutions was determined by the salt method. Graphically, according to the dependence of the optical density of the mixture solution at 620 nm on the protein concentration, it was calculated that the "golden number" is 31.3 μg/mL. A mixture of nanoparticles with 10 μg/mL of HRP (concentration below the "golden number") was prepared, to which an equal volume of antibody solution was added. The resulting solution of nanoparticles was stable to salt aggregation, interacted with a specific antigen, and possessed enzymatic activity. The use of this conjugate in the dot assay demonstrated an 8-fold increase in the antigen detection sensitivity with the addition of a substrate solution for HRP as compared to staining with only functionalized AuNPs without enzyme reaction.

In this work, we investigate a hybrid system based on a biocompatible polymer matrix loaded with a fluorescent photodynamic dye zinc phthalocyanine as a platform with high photodynamic activity in the first biological window and the ability to visualize the biodistribution of the system in vivo. In this regard, biocompatible polyelectrolyte carriers of submicron size were used, which enable efficient immobilization of low-molecular-weight dyes and carry out photodynamic therapy without uncontrolled release of the photodynamic agent. Since the thickness of the polyelectrolyte shell of the carrier do not exceed several tens of nanometers, and the lifetime of singlet oxygen enable motion over distances of up to several microns, the photodynamic activity of the immobilized agent can be observed even without the release of the photodynamic agent from the polyelectrolyte carrier, thus making the carrier itself a photodynamic agent. The ability to flexibly vary the composition of the polyelectrolyte shell of the carriers allows it to include functional organic and inorganic components, which makes it possible to provide the function of visualizing the biodistribution of the delivery system in vivo during circulation in the body. The system described in this work will provide additional functionalization of the carriers, such as the ability to visualization of the biodistribution of submicron polymer carriers loaded with photodynamic agents in laboratory mice in vivo which has been investigated in this work. These results open up a venue for the therapy based on the principles of "image-guided therapy".

A method for preparation of luminescent silicon coatings applicable to both rigid glass substrates and flexible nonwoven polymeric electrospun mats is proposed. This technique allows for synthesis of nanosized silicon crystallites that fluoresce in visible and near-IR light. Proposed approach to preparation of nanostructured fluorescent fibrous materials seems promising for applications in biosensing.

Quantum dots and gold nanoparticles are among the most common labels for immunochemical analysis. Methods for conjugating nanoparticles with antibodies, proteins and antigens are required in almost any test method based on antibody-antigen interaction. We examined particles of various sizes and functionalities for conjugation protocols. Physical adsorption methods for gold nanoparticles and quantum dots with epoxy and carboxyl groups on the surface for chemical reaction were considered.

Quantum dots (QDs) are modern nanoparticles with a wide potential for use in medicine, bioanalysis, as well as in optics and energetics. Different types of QDs can be produced depending on their synthesis method. QDs formed by semiconductor components able to mutual solid-solution formation named alloyed. This type of QDs has a high quantum yield and narrow emission peak but less chemical stability relative to core-shell type QDs. Better core-shell QDs stability explains by the additional surface shell covering. This approach can be applied to the alloyed QDs also. One-step hightemperature organometallic procedure is excellent in this regard due to its simplicity and consistency in the synthesis. However, QDs which obtained in this way are hydrophobic and do not dissolve in polar solutions such as water. Hydrophilization is used to convert QDs from a hydrophobic to a hydrophilic state. It was found that when hydrophilizing with β-mercaptoethanol, the quantum yield (QY) significantly increases, although when hydrophilizing with other ligands, it is just a decrease in the quantum yield that appears. This article investigates the process of hydrophilization of core-shell alloyed QDs in which an increase in QY is observed. For this, the effect on the optical properties of the amount of the hydrophilizing agent, long-term storage at room and low temperatures, and the effect of pH on hydrophilized QDs are considered.