Impedimetric biosensors represent a powerful and promising tool for studying and monitoring biological processes associated with proteins and can contribute to the development of new approaches in the diagnosis and treatment of diseases. The basic principles, analytical methods, and applications of hybrid impedimetric biosensors for express protein detection in biological fluids are described. The advantages of this type of biosensors, such as simplicity and speed of operation, sensitivity and selectivity of analysis, cost-effectiveness, and an ability to be integrated into hybrid microfluidic systems, are demonstrated. Current challenges and development prospects in this area are analyzed. They include (a) the selection of materials for electrodes and formation of nanostructures on their surface; (b) the development of efficient methods for biorecognition elements’ deposition on the electrodes’ surface, providing the specificity and sensitivity of biosensing; (c) the reducing of nonspecific binding and interference, which could affect specificity; (d) adapting biosensors to real samples and conditions of operation; (e) expanding the range of detected proteins; and, finally, (f) the development of biosensor integration into large microanalytical system technologies. This review could be useful for researchers working in the field of impedimetric biosensors for protein detection, as well as for those interested in the application of this type of biosensor in biomedical diagnostics.

The specific features are presented of the two-stage synthesis of structured microsystems based on zinc-oxide nanorods by ultrasonic spray pyrolysis and the low-temperature hydrothermal method, with nucleation suppressed in the bulk of the solution. It is shown that the use of two-stage synthesis provides control over the size and aspect ratio of separate nanorods and over the structure of the microsystem of nanorods as a whole. It is proposed to monitor the concentration of intrinsic surface defects by measuring the photocurrent under irradiation through narrow-band interference light filters.

In the research, light-sensitive structures based on a heterostructure of ZnO- nanorods/PbS colloidal quantum dots (CQDs) were fabricated. The paper describes technological features of obtaining coatings by the low-temperature hydrothermal method and fabrication of a ZnO-nanorods/PbS CQDs heterostructure. It is shown that this structure is capable of converting light into electrical energy. These structures are promising for use as gas sensors functioning at temperatures close to room temperature.

This paper presents a study of the gas sensitivity of a nanostructured zinc oxide coating to isopropyl alcohol vapor during heating, ultraviolet irradiation, as well as simultaneous heating and irradiation. Simultaneous heating to 150^oC and ultraviolet irradiation ensures an increase in the sensor layer response. A 10-fold decrease in the power consumption of an ultraviolet light-emitting diode results in a 1.2-fold decrease in the response of the sensor coating. Reducing the operating temperature of a gas sensor with low power consumption and achieving the required sensitivity can provide adsorption sensors integration into portable devices for monitoring ambient air quality. Keywords: zinc oxide, nanorods, gas sensor, UV irradiation, combined activation.

Impedimetric biosensors are used for detecting a wide range of analytes. The detection principle is a perspective for the development of new types of analytical devices for biomolecular diagnosis of diseases. Of particular interest are biosensors with very high sensitivities, capable of detecting trace amounts of biomarkers or drugs in biological fluids. Impedimetric biosensors possess a potential for increased sensitivity, since their electrodes can be modified with nanostructured materials, in particular zinc oxide. In this work, a miniature biosensor with an array of zinc oxide nanorods synthesized by the hydrothermal method has been created. Protein A was immobilized on the resulting structure, which was previously tested for binding to omalizumab by capillary electrophoresis. Using impedance spectroscopy, it was possible to detect the binding of omalizumab at concentrations down to 5 pg/mL. The resulting structures are suitable for creating reusable biosensor systems, since ZnO-coated electrodes are easily cleaned by photocatalytic decomposition of the bound molecules. The biosensor is promising for use in Point-of-Care systems designed for fast, multimodal detection of molecular markers of a wide range of diseases.