This article describes the synthesis of nanostructured copper oxide on copper wires and its application for the detection of hydrogen peroxide. Copper oxide petal nanostructures were obtained by a one-step hydrothermal oxidation method. The resulting coating is uniform and dense and shows good adhesion to the wire surface. Structure, surface, and composition of the obtained samples were studied using field-emission scanning electron microscopy along with energy-dispersive spectroscopy and X-ray diffractometry. The resulting nanostructured samples were used for electrochemical determination of the H₂O₂ content in a 0.1 M NaOH buffer solution using cyclic voltammetry, differential pulse voltammetry, and i–t measurements. A good linear relationship between the peak current and the concentration of H₂O₂ in the range from 10 to 1800 μM was obtained. The sensitivity of the obtained CuO electrode is 439.19 μA·mM⁻¹. The calculated limit of detection is 1.34 μM, assuming a signal-to-noise ratio of 3. The investigation of the system for sensitivity to interference showed that the most common interfering substances, that is, ascorbic acid, uric acid, dopamine, NaCl, glucose, and acetaminophen, do not affect the electrochemical response. The real milk sample test showed a high recovery rate (more than 95%). According to the obtained results, this sensor is suitable for practical use for the qualitative detection of H₂O₂ in real samples, as well as for the quantitative determination of its concentration.

This study investigated the morphological dependence of ZnO nanostructures, specifically nanotube- and nanorod-based electrodes, on their electrochemical performance for the detection of lead ions (Pb²⁺) in aqueous solutions. The results demonstrate that ZnO nanotubes exhibit significantly enhanced sensitivity compared to nanorods during CV measurements. During SWV measurements, the sensitivity (116.79 mA·mM⁻¹) and a lower limit of detection of 0.0437 μM were determined. The hollow, high-aspect-ratio structure of nanotubes provides a larger active surface area and facilitates better ion accessibility, resulting in superior electron transfer efficiency and catalytic activity. These results underscore the critical role of morphology in optimizing ZnO-based sensors. Analysis of real water samples from various natural reservoirs revealed no detectable lead, while lead was identified exclusively in artificially prepared samples containing water exposed to lead hunting shot. Over a 30-day period, the sensor retained over 95% of its initial performance when stored under vacuum conditions, demonstrating minimal signal degradation. Under ambient conditions, stability loss was attributed to moisture adsorption on the porous nanostructure. The sensor also displayed outstanding reproducibility, with current response variations across multiple probes remaining within 4%. The cost-effective and simple fabrication process of ZnO nanostructures further highlights their potential for scalable production, environmental monitoring, and integration into portable sensing devices.

Hydrogen peroxide is essential for biological processes and normally occurs in low concentrations in living organisms. However, exposure of plants to biotic and abiotic stressors can disrupt their defense mechanisms, resulting in oxidative stress with elevated H₂O₂ levels. This oxidative stress can damage cell membranes, impair photosynthesis, and hinder crucial plant functions. The primary focus of this article is to investigate the effects of salt and herbicide stress factors on the growth of rye samples. For precise quantification of the released H₂O₂ concentration caused by these stress factors, a non-enzymatic electrochemical sensor was developed, employing nanostructured CuO and Co₃O₄ oxides. Nanostructured electrodes exhibit high sensitivity and selectivity towards H₂O₂, making them suitable for detecting H₂O₂ in real samples with complex compositions. Rye samples exposed to NaCl- and glyphosate-induced stress demonstrated notable concentrations of released H₂O₂, displaying an increase of up to 30% compared to the control sample. Moreover, optical absorption measurements revealed a substantial decrease in chlorophyll concentration (up to 35% compared to the control group) in rye samples where elevated H₂O₂ levels were detected through electrochemical methods. These findings provide further evidence of the harmful effects of elevated H₂O₂ concentrations on plant vital functions.

This research investigates the enhancement of barley’s resistance to salt stress by integrating nanoparticles and employing a nanostructured Co₃O₄ sensor for the electrochemical detection of hydrogen peroxide (H₂O₂), a crucial indicator of oxidative stress. The novel sensor, featuring petal-shaped Co₃O₄ nanostructures, exhibits remarkable precision and sensitivity to H₂O₂ in buffer solution, showcasing notable efficacy in complex analytes like plant juice. The research establishes that the introduction of Fe₃O₄ nanoparticles significantly improves barley’s ability to withstand salt stress, leading to a reduction in detected H₂O₂ concentrations, alongside positive impacts on morphological parameters and photosynthesis rates. The developed sensor promises to provide real-time monitoring of barley stress responses, providing valuable information on increasing tolerance to crop stressors.

Stress caused by predator exposure can lead to various behavioural, physiological, stoichiometric, and biochemical changes in prey. Prior research has shown that growth under predation stress can cause the development of a diabetes-like biochemical phenotype in fruit flies. Exposure to predator risk during larval development decreases flies’ walking activity, improving their antipredator strategies. However, it is unclear which elements of walking behaviour make flies less conspicuous to predators. This study shows that fruit flies () grown with spiders walk shorter distances, accelerate faster and spend more time in a state of motion without movement (i.e., stomping in place) than control flies (). Under predation risk, adult flies grown with spiders survived better than control flies. We suggest that motions without movement may resemble sickness behaviour for predators, which we propose as the main reason for their better survival under direct exposure to predator attacks.

This article describes the synthesis of nanostructured cobalt oxide on iron wires and its application for the detection of hydrogen peroxide as working electrode for non-enzymatic electrochemical sensor. Cobalt oxide was obtained by the hydrothermal synthesis method using chloride and acetate anions. The resulting nanostructured coating obtained from the chloride precursor is a uniform homogeneous porous network of long nanofibers assembled into regular honeyсomb-like formations. In the case of an acetate precursor, instead of nanofibers, petal-like nanostructures assembled into honeycomb agglomerates are observed. The structure, surface, and composition of the obtained samples were studied using field-emission scanning electron microscopy along with energy-dispersive spectroscopy and X-ray diffractometry. The resultant nanostructured specimens were utilized to detect H2O2 electrochemically through cyclic voltammetry, differential pulse voltammetry, and i-t measurements. A comparative research has demonstrated that the nanostructures produced from the chloride precursor exhibit greater sensitivity to H2O2 and have a more appropriate morphology for designing a nanostructured sensor. A substantial linear correlation between the peak current and H2O2 concentration within the 20 to 1300 μM range was established. The Co3O4 electrode obtained exhibits a sensitivity of 505.11 μA·mM−1, and the electroactive surface area is calculated to be 4.684 cm2. Assuming a signal-to-noise ratio of 3,