Number of found documents: 366
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Electrochemical Methods for Determination of Three Tumor Biomarkers for Neuroblastoma: Homovanillic Acid, Vanillylmandelic Acid, and 5-Hydroxyindoleacetic Acid
Makrlíková, Anna; Kteno, E.; Fischer, J.; Navrátil, Tomáš; Vyskočil, V.
2016 - English
Tumor biomarkers – homovanillic acid, vanillylmandelic acid, and 5-hydroxyindoleacetic acid – have been determined at a screen-printed carbon electrode in small volume samples. For all measurements, Britton-Robinson buffer (0.04 moll−1, pH 3.0) was used as an optimum medium for all three analytes. Dependences of the peak current on the concentration were linear for all compounds, with the limits of quantification 0.8 μmol∙l–1 for homovanillic acid, 0.2 μmol∙l–1 for vanillylmandelic acid, and 0.2 μmol∙l–1 for 5-hydroxyindoleacetic acid. Depending on the results of the measurements, the future experiments should be performed in human urine. Keywords: Screen-printed carbon electrodes; Differential pulse voltammetry; Homovanillic acid, Vanillylmandelic acid Available at various institutes of the ASCR
Electrochemical Methods for Determination of Three Tumor Biomarkers for Neuroblastoma: Homovanillic Acid, Vanillylmandelic Acid, and 5-Hydroxyindoleacetic Acid

Tumor biomarkers – homovanillic acid, vanillylmandelic acid, and 5-hydroxyindoleacetic acid – have been determined at a screen-printed carbon electrode in small volume samples. For all measurements, ...

Makrlíková, Anna; Kteno, E.; Fischer, J.; Navrátil, Tomáš; Vyskočil, V.
Ústav fyzikální chemie J. Heyrovského, 2016

Voltammetric determination of homovanillic acid at boron doped diamond electrode for hollow fibre microextraction
Hrdlička, V.; Barek, J.; Navrátil, Tomáš
2016 - English
Presented work deals with hollow-fibre assisted liquid/liquid/liquid microextraction (HF-LPME) and subsequent voltammetric detection of clinical biomarker homovanillic acid (HVA). Three main areas are discussed: hollow fibre assisted extraction of HVA, voltammetric detection of HVA under basic conditions, and sensing in very small volumes. Using HF-PLME, HVA was extracted with 1-octanol as a supported liquid membrane with enrichment factor of 55 after 60 minutes of extraction. A novel method of miniaturized voltammetric determination of HVA using cathodically pretreated boron doped diamond electrode was also developed. Using differential pulse voltammetry, limit of detection, limit of quantificati was 1.9 mu mol dm(-3) on 6.6 mu mol dm(-3). Keywords: biomarkers; boron doped diamond electrode; hollow-fibre Available at various institutes of the ASCR
Voltammetric determination of homovanillic acid at boron doped diamond electrode for hollow fibre microextraction

Presented work deals with hollow-fibre assisted liquid/liquid/liquid microextraction (HF-LPME) and subsequent voltammetric detection of clinical biomarker homovanillic acid (HVA). Three main areas are ...

Hrdlička, V.; Barek, J.; Navrátil, Tomáš
Ústav fyzikální chemie J. Heyrovského, 2016

Electrochemical determination of 2-nitrofluorene and investigation of its interaction with DNA
Skalová, Štěpánka; Stávková, K.; Barek, J.; Vyskočil, V.
2016 - English
2-Nitrofluorene (2-NF) belongs to the group of nitrated polycyclic aromatic hydrocarbons. These compounds are categorized as environmental pollutants and they can manifest mutagenic and carcinogenic effects. A differential pulse voltammetric method at a glassy carbon electrode (GCE) was developed for sensitive determination of 2-NF. Under the optimum conditions found, a linear calibration dependence was obtained in the concentration range of 2 x 10(-7) - 1 x 10(-5) mol L-1, with the limit of quantification of 2 x 10 mol L-1. The practical applicability of this method was verified on the direct determination of 2-NF in a model sample of sand. Moreover, the mutual interaction between 2-NF and DNA was investigated using an electrochemical DNA biosensor (DNA-modified GCE). Cyclic voltammetry, electrochemical impedance spectroscopy, and square-wave voltammetry were employed in this study, confirming the formation of a 2-NF-DNA complex.\n Keywords: DNA biosensors; DNA interaction; glassy carbon electrode Available at various institutes of the ASCR
Electrochemical determination of 2-nitrofluorene and investigation of its interaction with DNA

2-Nitrofluorene (2-NF) belongs to the group of nitrated polycyclic aromatic hydrocarbons. These compounds are categorized as environmental pollutants and they can manifest mutagenic and carcinogenic ...

Skalová, Štěpánka; Stávková, K.; Barek, J.; Vyskočil, V.
Ústav fyzikální chemie J. Heyrovského, 2016

Fosfolipidy modifikovaná elektroda ze skelného uhlíku a její využití pro stanovení pesticidů
Švecová, H.; Sokolová, Romana; Součková, J.; Skopalová, J.; Barták, P.
2016 - Czech
Lipidové membrány jsou již mnoho let studovány jako modely biomembrán. Formování lipidových membrán na povrchu pevných elektrod poprvé popsali Tien a Salamon 1. Od té doby byly použity jako substráty pro lipidové vrstvy různé materiály jako např. stříbro 2, zlato 3, rtuť 4 nebo skelný uhlík 5. Lipidový film na povrchu elektrody je schopen akumulovat organické molekuly v závislosti na jejich náboji a na jejich hydrofilním respektive hydrofobním charakteru. Je známé, že mnoho organických látek, jako jsou pesticidy, léčiva a jiné farmakologicky významné látky, interagují s fosfolipidovou vrstvou a mastnými kyselinami v membráně a mohou být silně akumulovány v lipidové tkáni. In this article we described glassy carbon electrode modified with Asolectin (mixture of phosholipids). Properties of phospholipid layer, such as its thickness or solidity, were investigated using atomic force microscopy (AFM). The modified electrode was applied for square wave voltammetry (SWV) measurements to study interactions of pesticide paraquat with phospholipid layer and to detect paraquat selectively in real samples of river water. Keywords: paraquat; electrochemistry; phospholipids Available at various institutes of the ASCR
Fosfolipidy modifikovaná elektroda ze skelného uhlíku a její využití pro stanovení pesticidů

Lipidové membrány jsou již mnoho let studovány jako modely biomembrán. Formování lipidových membrán na povrchu pevných elektrod poprvé popsali Tien a Salamon 1. Od té doby byly použity jako substráty ...

Švecová, H.; Sokolová, Romana; Součková, J.; Skopalová, J.; Barták, P.
Ústav fyzikální chemie J. Heyrovského, 2016

Využití voltametrické metody pro sledování obsahu antioxidantu v biopalivech
Tomášková, M.; Chýlková, J.; Navrátil, Tomáš; Šelešovská, R.
2016 - Czech
Z hlediska kvality biopaliv je hlavním problémem jejich oxidační degradace během skladování, která vede ke vzniku produktů, které mohou způsobit ucpání palivových filtrů nebo korozi kovových částí motoru. Kromě toho má oxidační stabilita běžné motorové nafty podstatný vliv na stabilitu směsí s bionaftou. Právě nestabilita bionafty v porovnání s běžně používanou naftou vede k řadě otázek a obav při skladování biopaliv. Pro zpomalení oxidace a zajištění dostatečné stability je nutné nalézt vhodná aditiva a znát jejich přesné množství. Mezi antioxidanty používané pro zvýšení oxidační stability bionafty a jejich směsí s běžnou naftou patří i propyl galát 1-4. The simple and fast method for analysis of Propyl gallate (PG) in biofuels was proposed in this paper. Voltammograms of antioxidant under study were recorded using linear sweep voltammetry method at a gold disc electrode in supporting electrolyte containing 0.18 mol L-1 H2SO4 and 10 % ethanol. For purposes to monitor effects on fuel quality caused by oxidative degradation, the proposed method was applied to samples of biodiesel and Ekodiesel® (the blend of biodiesel with fuel diesel). The analysis of PG can be performed without pretreatment of Ekodiesel samples, and after extraction using distilled water in case of biodiesel samples. Keywords: propyl gallate; antioxidant; voltammetry Available at various institutes of the ASCR
Využití voltametrické metody pro sledování obsahu antioxidantu v biopalivech

Z hlediska kvality biopaliv je hlavním problémem jejich oxidační degradace během skladování, která vede ke vzniku produktů, které mohou způsobit ucpání palivových filtrů nebo korozi kovových částí ...

Tomášková, M.; Chýlková, J.; Navrátil, Tomáš; Šelešovská, R.
Ústav fyzikální chemie J. Heyrovského, 2016

Graphene Field-Effect Transistor as a Probe of Doping by Adsorbed Oxygen Molecules
Blechta, Václav; Mergl, Martin; Drogowska, Karolina; Kučera, Lukáš; Valeš, Václav; Červenka, Jiří; Kalbáč, Martin
2016 - English
Graphene has high potential in chemical sensing, thus understanding adsorption and charge transfer between graphene and adsorbed molecules is essential. We show that graphene field-effect transistor exhibits a moderate sensoric response towards oxygen at temperature of 150 °C. Field-effect transistors serve as a tool to probe electronic properties of graphene. We demonstrate that adsorption of oxygen molecules onto graphene leads to an upshift of Dirac point and light changes in mobility of charge carriers. Keywords: graphene; sensor; transistor Available at various institutes of the ASCR
Graphene Field-Effect Transistor as a Probe of Doping by Adsorbed Oxygen Molecules

Graphene has high potential in chemical sensing, thus understanding adsorption and charge transfer between graphene and adsorbed molecules is essential. We show that graphene field-effect transistor ...

Blechta, Václav; Mergl, Martin; Drogowska, Karolina; Kučera, Lukáš; Valeš, Václav; Červenka, Jiří; Kalbáč, Martin
Ústav fyzikální chemie J. Heyrovského, 2016

Charge Transport in Single Molecule Junctions of Spirobifluorene Scaffold
Hromadová, Magdaléna; Kolivoška, Viliam; Sokolová, Romana; Šebera, Jakub; Mészáros, G.; Valášek, M.; Mayor, C.
2016 - English
Single molecule conductance of two spirobifluorene molecules of different length have been studied by scanning tunneling break junction (STM–BJ) methodology. First molecule contains a tripodal spirobifluorene platform, whereas a second one contains the same platform with chemically attached p-phenyleneethynylene molecular wire. The conductance values change only slightly between these two molecules, which demonstrated that such a platform provides both highly conducting pathway and stable anchor for the future molecular electronic devices. Keywords: single molecule conductance; spirobifluorene; break junction Available at various institutes of the ASCR
Charge Transport in Single Molecule Junctions of Spirobifluorene Scaffold

Single molecule conductance of two spirobifluorene molecules of different length have been studied by scanning tunneling break junction (STM–BJ) methodology. First molecule contains a tripodal ...

Hromadová, Magdaléna; Kolivoška, Viliam; Sokolová, Romana; Šebera, Jakub; Mészáros, G.; Valášek, M.; Mayor, C.
Ústav fyzikální chemie J. Heyrovského, 2016

Redakčně upravená závěrečná zpráva projektu DF11P01OVV012: Nové materiály a technologie pro konzervaci materiálů památkových objektů a preventivní památkovou péči
Rathouský, Jiří; Slížková, Zuzana; Kotlík, P.
2016 - Czech
Projekt byl zaměřen na vývoj nových materiálů a technologií pro komplexní řešení problematiky uchování hodnot hmotného kulturního dědictví v ČR zejména s ohledem na čištění historických materiálů s využitím mikroemulzí a micelárních roztoků, konsolidaci objektů pomocí nanodisperzí hydroxidu vápenatého a modifikovaných ethylsilikátových gelů a preventivní ochranu materiálů proti působení vnějšího prostředí a biokorozi, včetně zachování jejich původního vzhledu. This project was focused on development of new materials and technologies for complex solution of problems with preservation of a cultural heritage in the Czech Republic. Main interests were conservation activities as cleaning of historical materials using microemulsions and micellar solutions, consolidation by calcium hydroxide and modified ethylsilicate gels and protection of materials against environment effects and biocorrosion, including protection of the original appearance of the historic materials. Keywords: consolidation; cleaning of historical materials; protection Available at various institutes of the ASCR
Redakčně upravená závěrečná zpráva projektu DF11P01OVV012: Nové materiály a technologie pro konzervaci materiálů památkových objektů a preventivní památkovou péči

Projekt byl zaměřen na vývoj nových materiálů a technologií pro komplexní řešení problematiky uchování hodnot hmotného kulturního dědictví v ČR zejména s ohledem na čištění historických materiálů s ...

Rathouský, Jiří; Slížková, Zuzana; Kotlík, P.
Ústav fyzikální chemie J. Heyrovského, 2016

Electrochemical determination of 2-nitrofluorene and investigation of its interaction with DNA
Skalová, Štěpánka; Stávková, K.; Barek, J.; Vyskočil, V.
2016 - English
2-Nitrofluorene (2-NF) belongs to the group of nitrated polycyclic aromatic hydrocarbons. These compounds are categorized as environmental pollutants and they can manifest mutagenic and carcinogenic effects. A differential pulse voltammetric method at a glassy carbon electrode (GCE) was developed for sensitive determination of 2-NF. Under the optimum conditions found, a linear calibration dependence was obtained in the concentration range of 210–7 – 110–5 mol L–1, with the limit of quantification of 2×10–7 mol L–1. The practical applicability of this method was verified on the direct determination of 2-NF in a model sample of sand. Moreover, the mutual interaction between 2-NF and DNA was investigated using an electrochemical DNA biosensor (DNA-modified GCE). Cyclic voltammetry, electrochemical impedance spectroscopy, and square-wave voltammetry were employed in this study, confirming the formation of a 2-NF–DNA complex. Keywords: DNA biosensor; DNA interaction; voltammetry Available at various institutes of the ASCR
Electrochemical determination of 2-nitrofluorene and investigation of its interaction with DNA

2-Nitrofluorene (2-NF) belongs to the group of nitrated polycyclic aromatic hydrocarbons. These compounds are categorized as environmental pollutants and they can manifest mutagenic and carcinogenic ...

Skalová, Štěpánka; Stávková, K.; Barek, J.; Vyskočil, V.
Ústav fyzikální chemie J. Heyrovského, 2016

Oxidation of Bioflavonoids in Respect to their Chemical Structure
Sokolová, Romana; Ramešová, Šárka; Kocábová, Jana; Degano, I.
2016 - English
The electrochemical oxidation of flavone luteolin, flavanone taxifolin and flavonols derived from quercetin was studied by cyclic voltammetry. Only small differences in the chemical structure of bioflavonoids resulted in extremely variable oxidation pathways and products. Products of oxidation and further decomposition were determined by HPLC-ESI-MS/MS and HPLC-DAD. Keywords: oxidation; flavonoids; voltammetry Available at various institutes of the ASCR
Oxidation of Bioflavonoids in Respect to their Chemical Structure

The electrochemical oxidation of flavone luteolin, flavanone taxifolin and flavonols derived from quercetin was studied by cyclic voltammetry. Only small differences in the chemical structure of ...

Sokolová, Romana; Ramešová, Šárka; Kocábová, Jana; Degano, I.
Ústav fyzikální chemie J. Heyrovského, 2016

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