In the last decade, there has been continuous competition between two methods for detecting the concentration of dissolved oxygen: amerometric (Clark electrode) and optical (quenching of the phosphorescence of the porphyrin metal complex). Each of them has obvious advantages and disadvantages. This competition is especially acute in the development of biosensors, however, an unbiased comparison is extremely difficult to achieve, since only a single detection method is used in each particular study. In this work, a microfluidic system with synchronous detection of the oxygen concentration by two methods was created for the purpose of direct comparison. The receptor element is represented by Saccharomyces cerevisiae yeast cells adsorbed on a composite material, previously developed by our scientific group. To our knowledge, this is the first work of this kind in which the comparison of the oxygen detection methods is carried out directly.

The development of different methods for tuning surface properties is currently of great interest. The presented work is devoted to the use of modified nanodiamonds to control the wetting and biological fouling of polymers using optical sensors as an example. We have shown that, depending on the type of modification and the amount of nanodiamonds, the surface of the same fluorinated polymer can have both bactericidal properties and, on the contrary, good adhesion to the biomaterial. The precise control of wetting and biofouling properties of the surface was achieved by the optimization of the modified nanodiamonds thermal anchoring conditions. In vitro and in vivo tests have shown that the fixation of amine functional groups leads to inhibition of biological activity, while the presence of a large number of polar groups of mixed composition (amide and acid chloride) promotes adhesion of the biomaterial and allows one to create a biosensor on-site. A comprehensive study made it possible to establish that in the first 5 days the observed biosensor response is provided by cells adhered to the surface due to the cell wall interaction. On the 7th day, the cells are fixed by means of the polysaccharide matrix, which provides much better retention on the surface and a noticeably greater response to substrate injections. Nevertheless, it is important to note that even 1.5 h of incubation is sufficient for the formation of the reliable bioreceptor on the surface with the modified nanodiamonds. The approach demonstrated in this work makes it possible to easily and quickly isolate the microbiome on the surface of the sensor and perform the necessary studies of its substrate specificity or resistance to toxic effects.

The obtainment of new luminophores for molecular sensorics of biosystems is becoming one of the urgent tasks in the field of chemical synthesis. The solution to each practical problem imposes its own limitations in the design of new structures with practically useful properties. The relationship between the structure and spectral properties is still to be unveiled. Three aza-BODIPY complexes with substituents of different natures were studied using time-resolved and steady-state fluorescence and absorption spectroscopy. The solvatochromic properties of aza-BODIPYs were studied with the use of a combined polyparametric approach and analysis by chemoinformatics methods for the first time. It was found that red shift of aza-BODIPY dyes was due to the increase of their structural lability. Predictive and experimental methods showed that the investigated aza-BODIPYs exhibited a positive solvatochromic effect, in contrast to classic BODIPYs (bearing C in the meso-position of the dipyrromethene core), which represents the negative solvatochromic properties. Spectral maxima in the area of the therapeutic window, low and predictable solvatochromism, and the ability to fine-tune the spectral characteristics make the investigated aza-BODIPYs promising scaffolds for the construction of bioengineering devices. Generalizations on the aza-BODIPYs’ design patterns were made in accordance with further bioimaging applications.

Objectives. Catalytically active materials are required in different chemical engineering processes. This makes the development of new materials with high efficiency and original ways in which to obtain them of significant interest. The present work investigates the synthesis of catalytically active material including electrode materials, as well as their improved efficiency due to the nanodecoration of their surface.Methods. An aluminum folio was nanoperforated (nanoscalloped) by high-voltage anodization in an acidic medium. The effective electrode material was obtained as a metallic nickel replica rather than an oxide layer of the product. To study the surface state of aluminum obtained in this manner, a scanning electron microscope (Hitachi-SU8200) was used. The elementary composition of the aluminum was determined by back-scattered X-ray irradiation.Results. The nickel replica obtained in the above-described process exceeded the catalytic activity estimated by methanol oxidation of the unprocessed nickel 70–150 times.Conclusions. The present paper demonstrates the potential of creating effective catalytically active nanopillar materials using the metallic rather than metal-oxide part of a layer of anodized aluminum as a matrix template.

Objectives. Herein, the effects of cationic polyelectrolytes on the properties of solid substrate immobilized acid–base indicators are investigated to predict shifts in their spectral patterns and characteristics. Methods. The properties of the silica gel immobilized indicator dye in a solution of the cationic polyelectrolyte were studied using automatic photometric titration in the visible region and spectrophotometry using a specialized computerized setup. Results. The measured pKa value of the immobilized dye, which had shifted by three units to the acidic region, was very similar to the pKa value observed for the indicator in the modifying polymer solution. The observed change in pKa of the immobilized dye and the influence of the solution’s ionic strength were attributed to the local electric potential of the polymer globule. In contrast to the processes associated with covalent immobilization, the effect exerted by the solution’s ionic strength on the indicator reaction diminishes, which, in turn, affects the measured values obtained.Conclusions. The creation of a sensor for continuous visualization of pH levels based on Congo Red immobilized on silica gel was described. Here, a color transition was noted between pH 1 and 4. These materials can be used to monitor metal extraction processes from industrial effluents or to optimize the extraction of valuable actinides. The approach demonstrated in this work can be applied to immobilize other indicators for pH level monitoring purposes or the production of sensors for other analytes.