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Reactive oxygen species (ROS) are presently thought to play important role in an increasing number of the physiological and pathological processes in living organisms. Various chemiluminescent (CL) compounds have been studied in order to find suitable and specific probes for the detection of particular ROS species. The CL of luminol is known to be non-specific and can be induced by various oxidants. Two Cypridina luciferin analogues, CLA and MCLA, have been used for the detection of ROS in vivo. CLAs are thought to emit light only when reacting with superoxide and singlet oxygen. It is possible to distinguish the particular ROS by using a specific quencher or scavenger, e.g. superoxide dismutase (SOD) or sodium azide (NaN(3)). The CL reactions of luminol (3-aminophthalhydrazide), CLA [2-methyl-6-phenyl-3,7-dihydroimidazo(1,2α) pyrazin-3-one] and MCLA [2-methyl-6-(p-methoxyphenyl)-3,7-dihydroimidazo(1,2α) pyrazin-3-one] were studied in three hydrogen peroxide decomposition systems (H(2)O(2)-HRP; H(2)O(2)-CuSO(4); and H(2)O(2)-NaOCl). The measurements were carried out in phosphate buffer, pH 7.4, at 25°C, using a luminometer (Fluoroskan Ascent FL and Sirius C). NaN(3) was used as the specific quencher of singlet oxygen. The results demonstrate that the proclaimed specificity of the CL of Cypridina luciferin analogues towards singlet oxygen has to be discussed.

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In this initial study, the toxicity effect of silver NPs against a model unicellular eukaryotic organism of Paramecium caudatum was studied. For the purpose of this study, a dialysis-based method was adapted, which allowed the preparation of stable aqueous dispersions of silver NPs in various silver concentrations that were necessary for the evaluation of toxicity limits of these particles. The obtained results demonstrate that the silver NPs do not exhibit any toxicity action against the tested unicellular eukaryotic organism below the concentration of 25 mg • L -1 whereas ionic silver retains its toxicity even at a concentration of 0.4 mg • L -1 . Such a considerable difference in the toxicity effect of these two forms of silver has not been observed in the previously published study concerning bacteria (

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This work describes the method for total antioxidant capacity (TAC) and/or total content of phenolics (TCP) analysis in wines using microdialysis online-coupled with amperometric detection using a carbon microfiber working electrode. The system was tested on 10 selected wine samples, and the results were compared with total reactive antioxidant potential (TRAP), oxygen radical absorbance capacity (ORAC), and chemiluminescent determination of total antioxidant capacity (CL-TAC) methods using Trolox and catechin as standards. Microdialysis online-coupled with amperometric detection gives similar results to the widely used cyclic voltammetry methodology and closely correlates with ORAC and TRAP. The problem of electrode fouling is overcome by the introduction of an electrochemical cleaning step (1−2 min at the potential of 0 V vs Ag/ AgCl). Such a procedure is sufficient to fully regenerate the electrode response for both red and white wine samples as well as catechin/Trolox standards. The appropriate size of microdialysis probes enables easy automation of the electrochemical TAC/ TCP measurement using 96-well microtitration plates.