Anatoly Aleksandrovich Evstrapov

Subject of study . This study investigates the optical properties of a composite based on an epoxy-acrylate oligomer modified with ZnO nanoparticles (NPs). This study also considers the development of multifunctional polymer coatings for solar cells capable of converting ultraviolet (UV) radiation into visible light. Aim of study. The aim of this study is to develop a model establishing a cascade energy-transfer mechanism to enhance fluorescence. Method. The optical properties were investigated by absorption spectroscopy and fluorimetry using a Hitachi U-3410 spectrophotometer and a Hitachi F-4010 spectrofluorimeter. Main results . A cascade mechanism for fluorescence enhancement was experimentally established and theoretically substantiated. ZnO NPs acted as nanoresonators, and they absorbed UV radiation and underwent recombination through an exciton–polariton channel with subsequent re-emission. The re-emitted photons were effectively absorbed by graphene quantum dots (GQDs), leading to radiative transitions in the visible spectral range (410–480 nm). A cascade energy-transfer mechanism from the ZnO nanoresonators to the GQDs was established and substantiated for the first time. Practical significance. The obtained results enable the development of coatings that enhance the efficiency of solar cells.

The review presents the classification of point-of-care (POC) devices, and discusses the main characteristics of the devices and the requirements for them. The differences between the POC testing method and the laboratory method of analysis are considered. Examples of devices that fit the definition of POC for diagnosing infectious diseases are given.

A quantitative polymerase chain reaction in real time (real time PCR) has been implemented on polymer microfluidic devices made of polycarbonate and polypropylene. The threshold cycle is determined based on the inflection point of the first-order logistic growth function, which reliably approximates the PCR curve in the absence of interfering factors, for example, the presence of bubbles in the reaction chamber. Use of statistical criteria (generalized Student's criterion, one-way analysis of variance) revealed the insignificance of the influence of the polymer type on the estimation of the position of the threshold cycle in terms of the previously selected algorithm for its search. When using an alternative algorithm for finding the threshold cycle based on the plotting of a tangent to the kinetic curve, in some cases there is a significant influence of the polymer type on the estimation of the position of the threshold cycle and, as a consequence, on the result of quantitative analysis. Proposed and discussed are algorithms for detecting bubbles in the reaction chamber based on the detection of a discrepancy in the measurement sequence associated with both estimates of the approximating dependence's parameters and the characteristics of the time series formed by approximation errors.

Microfluidics is a rapidly growing area that provides innovations in biotechnology, medical diagnostics, and life science. Along with the commercial solutions, there are open-source projects aimed to make such technologies more affordable and flexible for end users. In this article, we developed an open-source, low-cost, and easy-to-use microfluidic pressure controller with a modular design based on electropneumatic regulators to introduce liquids into microfluidic devices under constant pressures. For implementation of complex experimental protocols, the controller contains a vacuum pump, relay outputs, analog inputs, and digital inputs/outputs to connect external equipment. It can be operated using five displays and an encoder or from a personal computer in a manual or automatic regime through the custom open-source software. In this study, we applied this pressure controller for the generation of water-in-oil droplets in microfluidic flow-focusing droplet generators. Droplets’ diameters linearly depended on the dispersed and continuous phases’ ratio in the range 5– $65 \mu \text{m}$ . In all the cases, the generation regimes were stable for at least 4 h. Direct comparison of the droplet generation obtained with the developed pressure controller and precise syringe pumps showed that it will suit the needs of the microfluidic community for different flow-based lab-on-a-chip applications, as a more affordable and flexible solution for introducing liquids and controlling flow sensors, heaters, valves, light sources, and so on during experiments.

The set of domestic devices and reagent kits for molecular genetic analysis has been developed, which provides for all stages of the study, from the automated isolation of nucleic acids, their amplification with real-time detection to classical and genome-wide DNA sequencing. With the help of the created equipment and reagent kits, approaches for the specific indication of pathogens of a wide range of diseases have been successfully implemented. The high efficiency of the proposed approaches is shown by the example of detecting and analyzing the RNA of the pathogen SARS-CoV-2 in the fight against the COVID-19 coronavirus pandemic (7 figs, bibliography: 4 refs).

Droplet microfluidics is an extremely useful and powerful tool for industrial, environmental, and biotechnological applications, due to advantages such as the small volume of reagents required, ultrahigh-throughput, precise control, and independent manipulations of each droplet. For the generation of monodisperse water-in-oil droplets, usually T-junction and flow-focusing microfluidic devices connected to syringe pumps or pressure controllers are used. Here, we investigated droplet-generation regimes in a flow-focusing microfluidic device induced by the negative pressure in the outlet reservoir, generated by a low-cost mini diaphragm vacuum pump. During the study, we compared two ways of adjusting the negative pressure using a compact electro-pneumatic regulator and a manual airflow control valve. The results showed that both types of regulators are suitable for the stable generation of monodisperse droplets for at least 4 h, with variations in diameter less than 1 µm. Droplet diameters at high levels of negative pressure were mainly determined by the hydrodynamic resistances of the inlet microchannels, although the absolute pressure value defined the generation frequency; however, the electro-pneumatic regulator is preferable and convenient for the accurate control of the pressure by an external electric signal, providing more stable pressure, and a wide range of droplet diameters and generation frequencies. The method of droplet generation suggested here is a simple, stable, reliable, and portable way of high-throughput production of relatively large volumes of monodisperse emulsions for biomedical applications.