Currently, significant progress is being made in the prevention, treatment and prognosis of many types of cancer, using biological markers to assess current physiological processes in the body, including risk assessment, differential diagnosis, screening, treatment determination and monitoring of disease progression. The interaction of protein coding gene CD44 with the corresponding ligands promotes the processes of invasion and migration in metastases. The study of new and rapid methods for the quantitative determination of the CD44 protein is essential for timely diagnosis and therapy. Current methods for detecting this protein use labeled assay reagents and are time consuming. In this paper, a fiber-optic biosensor with a spherical tip coated with a thin layer of zinc oxide (ZnO) with a thickness of 100 nm, deposited using a low-cost sol–gel method, is developed to measure the CD44 protein in the range from 100 aM to 100 nM. This sensor is easy to manufacture, has a good response to the protein change with detection limit of 0.8 fM, and has high sensitivity to the changes in the refractive index (RI) of the environment. In addition, this work demonstrates the possibility of achieving sensor regeneration without damage to the functionalized surface. The sensitivity of the obtained sensor was tested in relation to the concentration of the control protein, as well as without antibodies—CD44.

Recently, the use of various dyes in the cellulose, textile, plastics and rubber industries has resulted in severe toxic and dye contamination of wastewater. These toxic dyes are not biodegradable and have a detrimental effect on the environment, blocking sunlight and reducing photosynthesis. Consequently, there is an urgent need to develop a low-cost effective technology for purifying wastewater from harmful organic pollutants. In this context, photocatalysis is an advanced, environmentally friendly oxidation process for wastewater treatment. Recent studies have shown that the use of semiconductor photocatalytically active materials with a wide band gap is an effective method for the decomposition of organic pollutants in aqueous solutions. In this work, a low-cost technology for the synthesis of composite semiconductor zinc oxide / graphene oxide (ZnO / GO) materials by chemical deposition from an aqueous solution has been developed. The morphology, structural and photoluminescent properties of the synthesized ZnO/GO samples with different graphene oxide concentration have been studied. The research of the photocatalytic activity of synthesized zinc oxide – graphene oxide composite materials is carried out by observing an aqueous solution of rhodamine B dye degradation under ultraviolet illumination.

In this study, an enzyme-free electrochemical sensor based on zinc oxide (ZnO) nanorods synthesized by the thermal decomposition of zinc acetate is presented. The suggested approach ensures simplicity, environmental friendliness, and scalability of the process without the use of an autoclave or high pressure. The morphology and structure of the samples are studied using SEM, TEM, XRD, Raman, FTIR, XPS, PL, and UV-Vis spectroscopy. It is found that heat treatment at 450 °C increases the degree of crystallinity, increases the size of crystallites, and reduces the concentration of surface defects, which leads to improved optical and electrochemical characteristics of the material. Beyond conventional sensitivity metrics, our study demonstrates that the selective detection of ascorbic acid (AA) and uric acid (UA) can be achieved by controlling the applied potential on a single ZnO electrode, an approach that leverages differences in redox energetics and surface interaction dynamics rather than complex surface functionalization. It is shown in this work that the synthesized ZnO samples subjected to heat treatment in air at 450 °C exhibit high sensitivity to ascorbic acid (9951.87 μA·mM⁻¹·cm⁻²; LoD = 1.11 μM) at a potential of 0.2 V and to uric acid (5762.48 μA·mM⁻¹·cm⁻²; LoD = 1.71 μM) in a phosphate buffer solution (pH 7) at a potential of 0.4 V with a linear range of 3 mM, offering a way to create simplified multicomponent electrochemical biosensors based on potential-controlled selectivity.

Nanostructured semiconductor ZnO and ZnO-GO samples were synthesized at room temperature by chemical bath deposition technique. In this work, the electrochemical non-enzymatic determination of ascorbic acid was studied using the grown nanostructures deposited on a glassy carbon electrode. The morphology and structural properties of the synthesized nanostructured materials were analyzed using a scanning electron microscope and an X-ray diffractometer. The electrochemical properties were studied by the methods of cyclic voltammetry using a single-channel potentiostat-galvanostat. The sensitivity of the obtained electrodes was calculated based on concentrations of ascorbic acid in phosphate buffer solution from 0.3 mM to 3 mM at various scanning speeds. Thus, it was found that the sensitivity of the ZnO-GO sample is lower than that of the ZnO sample, which may be due to the dielectric properties of graphene oxide. However, after annealing in the atmosphere, the sensitivity of the ZnO-GO sample increased, which is associated with a decrease in defects in the sample and an increase in the specific surface area of the samples. As a result of the research, a modified ZnO-GO/GCE electrode with a high sensitivity of 386 μAM-1cm-2 was created, which is promising for use as the basis of a biosensor for determining the level of vitamin C in blood, food, and drugs. Полупроводниковые наноструктурированные образцы ZnO и ZnO-GO были получены при комнатной температуре методом химического осаждения из раствора. В работе исследовано электрохимическое неферментативное определение аскорбиновой кислоты с помощью полученных наноструктур, нанесённых на стеклоуглеродный электрод. Морфология и структурные свойства изготовленных наноструктурированных материалов были проанализированы с помощью электронного растрового микроскопа и рентгеновского дифрактометра. Электрохимические свойства были исследованы методами циклической вольтамперометрии на одноканальном потенциостате-гальваностате. Чувствительность полученных электродов была рассчитана для концентраций аскорбиновой кислоты в фосфатно-буферном растворе от 0,3мМ до 3 мМ при различных скоростях сканирования. Таким образом, было выявлено, что чувствительность образца ZnO-GO ниже, чем у образца ZnO, что может быть связано с диэлектрическими свойствами оксида графена. Однако после отжига в атмосфере чувствительность образца ZnO-GO повысилась, что связано с уменьшением дефектов в образце и увеличением удельной поверхности образцов. В результате исследований был получен модифицированный ZnO-GO/GCE электрод с высокой чувствительностью 386 мкАМ-1см-2, перспективный для использования в качестве основы биосенсора для определения уровня витамина C в крови, пищевых продуктах и лекарствах. ZnO және ZnO - GO наноқұрылымды жартылай өткізгіш үлгілері ерітіндіден химиялық тұндыру әдісімен бөлме температурасында алынды. Жұмыста шыны көміртекті электродқа қолданылатын алынған наноқұрылымдардың көмегімен аскорбин қышқылының электрохимиялық ферментативті емес анықтамасы зерттелді. Өндірілген наноқұрылымды материалдардың морфологиясы мен құрылымдық қасиеттері электронды растрлық микроскоп пен рентгендік дифрактометрдің көмегімен талданды. Электрохимиялық қасиеттері бір арналы потенциостат-гальваностаттағы циклдік вольтамметрия және амперометрия әдістерімен зерттелді. Алынған электродтардың сезімталдығы әртүрлі сканерлеу жылдамдықтарында 0,3 мМ-ден 3 мМ-ге дейінгі фосфат-буферлік ерітіндідегі аскорбин қышқылының концентрациясы үшін есептелген. Осылайша, ZnO - GO үлгісінің сезімталдығы ZnO үлгісіне қарағанда төмен екендігі анықталды, бұл графен оксидінің диэлектрлік қасиеттеріне байланысты болуы мүмкін. Алайда, атмосферада күйдірілгеннен кейін ZnO-go үлгісінің сезімталдығы жоғарылады, бұл үлгідегі ақаулардың азаюына және үлгілердің меншікті бетінің ұлғаюына байланысты. Зерттеулер 386 мкАМ-1 см-2 жоғары...

In this paper, the synthesis of high-quality nanostructured zinc oxide (ZnO) and zinc oxide-graphene oxide (ZnO-GO) nanocomposites was carried out by a simple and efficient cost-effective chemical bath deposition method. The effect of different GO concentrations as well as thermal treatment on the structural, optical and photoluminescent properties of ZnO-GO semiconductor composites was investigated. All the synthesised samples were studied by electron microscopy, energy dispersive X-ray and Raman spectroscopy. ZnO usually exhibits luminescence in the visible region of the spectrum due to various intrinsic defects. This emission can be controlled by surface modification, doping and various treatments of the synthesised materials after synthesis. The considered ZnO-GO composites were subjected to thermal treatment in air at 375°C for one hour. The study of photoluminescence spectra showed that the heat treatment affects different types of optical recombination in the considered samples of zinc oxide - graphene oxide composites. The improved photoluminescence properties of ZnO-GO nanocomposites make them promising for application in various optical devices of nano- and microelectronics.

Zinc oxide nanostructures attract considerable attention of researchers due to their unique properties such as electrical conductivity, piezoelectric properties, optical transparency, emission, wide forbidden zone. Zinc oxide nanopowders are obtained by various methods: hydrothermal synthesis, sol-gel method, pyrolysis, chemical precipitation from solution and others. The task of development of low-cost methods of zinc oxide synthesis with high reproducibility is actual. The thermal decomposition method is a controlled relatively inexpensive method that can enable large scale production without the use of complex equipment and expensive materials. In this work, nanostructured ZnO samples were prepared by thermal decomposition of zinc acetate dehydrate at temperatures 400 ̊С and 700 ̊С. The influence of such synthesis parameters as duration and temperature on the morphology and structural properties of the obtained samples was investigated. It was found that the morphology of the synthesised ZnO samples significantly depends on the synthesis temperature. The obtained Raman scattering spectra show characteristic peaks of zinc oxide and carbon. An efficient, inexpensive method for the synthesis of zinc oxide nanoparticles with controlled morphology, promising for use as photocatalysts, the basis for the development of sensor devices, is presented.