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[en] This work describes the development of hydrogen peroxide detection based on Poly-ortho-phenylenediamine modified Platinum disk microelectrode (50 μm in diameter). The electrochemical performances of H2O2 detection were studied using Chronoamperometry, Cyclic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS) techniques in Phosphate Buffer Solution (PBS) pH 7.4. Effect of potential, electrode size, and various concentrations of H2O2, among others, were investigated by tracking the impedance changes at a specific perturbation frequency. To obtain the Charge transfer resistance (Rct) values, a modified Randles Equivalent Circuit was modelled and fitted to Nyquist Plot. Then, this sensor was further applied in the detection of H2O2 in antiseptic mouthwash with percent recovery of 97 % ± 0.14 (x103 kΩ). (author)
[en] Prangos ferulacea is a member of Apiaceae family, is a popular fodder for livestock production and an important species in rangeland restoration. The objectives of the research are the comparative phytotoxic activity of aqueous and hydroalcoholic extracts obtained from different organs (flower, shoot and leaf) of P. ferulacea on antioxidant response of Trifolium resupinatum was investigated in a laboratory bioassay. Antioxidant enzyme activities including catalase (CAT), peroxidase (POD), ascorbic peroxidase (APX), and superoxide dismutase (SOD), in line with content of malondialdehyde (MDA) and hydrogen peroxide were measured. Results indicated that hydroalcoholic extract of P. ferulaceae flower possess the highest total phenolic content as well as highest phytotoxic effect on T. resupinatum. The highest antioxidant enzyme activity belonged to hydroalcoholic treatment. The treated T. resupinatum seedlings experienced lipid peroxidation at high extract concentrations (12% of hydroalcoholic and 100% of aqueous extract) as evidenced by increased concentration of MDA. In response to this, the activities of SOD, CAT, POD and APX increased at lower extract concentrations but significantly dropped as concentrations increased. According to results of this study, rehabilitation of T. resupinatum sites through the use of P. ferulaceae will probably not be successful.
[en] H2O2 and free radicals are correlated with inflammatory diseases, cellular transformation and carcinogenesis. Experiments studying their direct or indirect influence in vivo, and/or, in cell cultures were still positive. In the contrary, reactions or products, which decrease level(s) of free radicals/H2O2 (i) directly, (ii) indirectly by an increase of SOD, catalase and peroxydase activities zeroed the above described phenomena. It is the case of the domain number 2 (that contains copper) of the Scorpion's blood pigment (hemocyanin), (i) which possesses SOD-, catalase-and peroxyde-like properties, resistant, at least, at 4000Gy, furthermore explaining the especially high radioresistance of scorpions. (author)
[en] Hydrogen peroxide (H2O2) is one type of reactive oxygen species (ROS) that can lead to a variety of forms of oxidative stress damage in human beings. Numerous methods have been used to detect H2O2 concentrations in various environments, however, these often suffer from inadequate detection limits, instrumental complexity, and multi-step experimental design, which may render them unfeasible for the required application. Herein, we report on a novel method for H2O2 detection that utilizes thiol-based SiOx nanodots (S-SiOx NDs) to initiate a sol-gel phase transition which can be observed by naked eye. This approach could lead to a very simple, rapid, and low cost method for H2O2 detection down to 5.8 μM, which is lower than the FDA regulation for H2O2 in food packaging. Furthermore, using a PL spectrometer allows H2O2 detection down to 0.01 μM. This S-SiOx NP system allows researchers the flexibility to choose between rapid visible detection of H2O2, or very high sensitivity detection by PL spectrometry. (paper)