Increasing urbanization and industrialization lead to the release of metals into the biosphere, which has become a serious issue for public health. In this paper, the direct electrochemical reduction of zinc ions is studied using electrochemically reduced graphene oxide (ERGO) modified glassy carbon electrode (GCE). The graphene oxide (GO) was fabricated using modified Hummers method and was electrochemically reduced on the surface of GCE by performing cyclic voltammograms from 0 to -1.5 V. The modification was optimized and properties of electrodes were determined using electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The determination of Zn(II) was performed using differential pulse voltammetry technique, platinum wire as a counter electrode, and Ag/AgCl/3 M KCl reference electrode. Compared to the bare GCE the modified GCE/ERGO shows three times better electrocatalytic activity towards zinc ions, with an increase of reduction current along with a negative shift of reduction potential. Using GCE/ERGO detection limit 5 ng·mL-1 was obtained.

• Klíčová slova
• carbon, cyclic voltammetry, electrochemical impedance spectroscopy, electrochemistry, graphene oxide, heavy metal detection, reduced graphene oxide,
• Publikační typ
• časopisecké články MeSH

The aim of the study was the preparation of a liposome complex with encapsulated lead ions, which were electrochemically detected. In particular, experiments were focused on the potential of using an electrochemical method for the determination of free and liposome-encapsulated lead and determination of the encapsulation efficiency preventing the lead toxicity. Primarily, encapsulation of lead ions in liposomes and confirmation of successful encapsulation by electrochemical methods was done. Further, the reduction effect of the liposome matrix on the detected electrochemical signal was monitored. Besides encapsulation itself, comparison of toxicity of free lead ions and lead ions encapsulated in liposome was tested. The calculated IC50 values for evaluating the lead cytotoxicity showed significant differences between the lead enclosed in liposomes (28 µM) and free lead ions (237 µM). From the cytotoxicity studies on the bacterial strain of S. aureus it was observed that the free lead ions are less toxic in comparison with lead encapsulated in liposomes. Liposomes appear to be a suitable carrier of various substances through the inner cavity. Due to the liposome structure the lead enclosed in the liposome is more easily accepted into the cell structure and the toxicity of the enclosed lead is higher in comparison to free lead ions.

• MeSH
• elektrochemické techniky * MeSH
• liposomy chemie   MeSH
• nanočástice toxicita   MeSH
• olovo toxicita   MeSH
• spektrofotometrie atomová MeSH
• Staphylococcus aureus účinky léků   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• liposomy MeSH
• olovo MeSH

Electrochemical detection of quantum dots (QDs) has already been used in numerous applications. However, QDs have not been well characterized using voltammetry, with respect to their characterization and quantification. Therefore, the main aim was to characterize CdTe QDs using cyclic and differential pulse voltammetry. The obtained peaks were identified and the detection limit (3 S/N) was estimated down to 100 fg/mL. Based on the convincing results, a new method for how to study stability and quantify the dots was suggested. Thus, the approach was further utilized for the testing of QDs stability.

• MeSH
• kadmium chemie   farmakologie   MeSH
• kur domácí MeSH
• kvantové tečky chemie   terapeutické užití   ultrastruktura   MeSH
• telur chemie   farmakologie   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• kadmium MeSH
• telur MeSH

The aim of this study was to investigate the effect of molds on levels of low molecular mass thiols in grasses. For this purpose, the three grass species Lolium perenne, Festulolium pabulare and Festulolium braunii were cultivated and sampled during four months, from June to September. The same species were also grown under controlled conditions. High-performance liquid chromatography with electrochemical detection was used for quantification of cysteine, reduced (GSH) and oxidized (GSSG) glutathione, and phytochelatins (PC2, PC3, PC4 and PC5). Data were statistically processed and analyzed. Thiols were present in all examined grass species. The effect of fungicide treatments applied under field conditions on the content of the evaluated thiols was shown to be insignificant. Species influenced (p < 0.05) PC3 and GSSG content. F. pabulare, an intergeneric hybrid of drought- and fungi-resistant Festuca arundinacea, was comparable in PC3 content with L. perenne and F. braunii under field conditions. Under controlled conditions, however, F. pabulare had higher (p < 0.05) PC3 content than did L. perenne and F. braunii. Under field conditions, differences between the evaluated species were recorded only in GSSG content, but only sampling in June was significant. F. pabulare had higher (p < 0.05) GSSG content in June than did L. perenne and F. braunii.

• MeSH
• houby * MeSH
• lipnicovité chemie   mikrobiologie   MeSH
• molekulová hmotnost MeSH
• sulfhydrylové sloučeniny analýza   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• sulfhydrylové sloučeniny MeSH

Cadmium, as a hazardous pollutant commonly present in the living environment, represents an important risk to human health due to its undesirable effects (oxidative stress, changes in activities of many enzymes, interactions with biomolecules including DNA and RNA) and consequent potential risk, making its detection very important. New and unique technological and biotechnological approaches for solving this problems are intensely sought. In this study, we used the commonly occurring potential pathogenic microorganism Staphylococcus aureus for the determination of markers which could be used for sensing of cadmium(II) ions. We were focused on monitoring the effects of different cadmium(II) ion concentrations (0, 1.25, 2.5, 5, 10, 15, 25 and 50 μg mL(-1)) on the growth and energetic metabolism of Staphylococcus aureus. Highly significant changes have been detected in the metabolism of thiol compounds-specifically the protein metallothionein (0.79-26.82 mmol/mg of protein), the enzyme glutathione S-transferase (190-5,827 μmol/min/mg of protein), and sulfhydryl groups (9.6-274.3 μmol cysteine/mg of protein). The ratio of reduced and oxidized glutathione indicated marked oxidative stress. In addition, dramatic changes in urease activity, which is connected with resistance of bacteria, were determined. Further, the effects of cadmium(II) ions on the metabolic pathways of arginine, β-glucosidase, phosphatase, N-acetyl β-d-glucosamine, sucrose, trehalose, mannitol, maltose, lactose, fructose and total proteins were demonstrated. A metabolomic profile of Staphylococcus aureus under cadmium(II) ion treatment conditions was completed seeking data about the possibility of cadmium(II) ion accumulation in cells. The results demonstrate potential in the application of microorganisms as modern biosensor systems based on biological components.

• Klíčová slova
• Brdicka reaction, Staphylococcus aureus, biosensor, cadmium, electrochemistry, high performance liquid chromatography with electrochemical detection, metabolic activity, metabolome, microbiome, spectrophotometry, voltammetry,
• MeSH
• biosenzitivní techniky metody   MeSH
• disacharidy metabolismus   MeSH
• elektrochemické techniky MeSH
• fosfatasy metabolismus   MeSH
• glutathion metabolismus   MeSH
• glutathiondisulfid metabolismus   MeSH
• glutathiontransferasa metabolismus   MeSH
• hydrolasy metabolismus   MeSH
• kadmium analýza   metabolismus   farmakologie   MeSH
• látky znečišťující životní prostředí analýza   metabolismus   farmakologie   MeSH
• metabolismus účinky léků   MeSH
• metalothionein metabolismus   MeSH
• monosacharidy metabolismus   MeSH
• proliferace buněk účinky léků   MeSH
• proteiny metabolismus   MeSH
• Staphylococcus aureus cytologie   účinky léků   metabolismus   MeSH
• sulfhydrylové sloučeniny metabolismus   MeSH
• ureasa metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• arginine deiminase MeSH Prohlížeč
• disacharidy MeSH
• fosfatasy MeSH
• glutathion MeSH
• glutathiondisulfid MeSH
• glutathiontransferasa MeSH
• hydrolasy MeSH
• kadmium MeSH
• látky znečišťující životní prostředí MeSH
• metalothionein MeSH
• monosacharidy MeSH
• proteiny MeSH
• sulfhydrylové sloučeniny MeSH
• ureasa MeSH