Digitální knihovnaUPCE
 

8/2013-14 Sensing in Electroanalysis

Permanentní URI k tomuto záznamuhttps://hdl.handle.net/10195/56677

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201424

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Nyní se zobrazuje 1 - 10 z 24
  • Náhled
    ČlánekOtevřený přístuppeer-reviewedpublished
    Development and characterization of layer-by-layer biosensors based on PEI(+)/GOx(-) layers using label-free methods
    (Univerzita Pardubice, 2014) David, Melinda; Florescu, Monica; Barsan, Madalina M.; Tugulea, Laura; Brett, Christopher M. A.
    Biosensors, as analytical devices, demonstrate unique efficiency in translating biochemical events into easily measurable electrical signals by using biological recognition elements, especially enzymes. Of the possible enzyme immobilisation methods, the layer-by-layer (LBL) technique, based on electrostatic interactions between layers, has the advantages of low cost, using small amount of materials, and leads to the formation of highly ordered and reproducible biosensor architectures. In this study, LbL biosensor construction has been evaluated. The substrates used were Au surfaces and mediated carbon-ink screen-printed electrodes. The gold electrodes were first functionalized with amino moieties by covalent linkage of cysteamine (Cys) through Au-S bonds. These allowed the linking of polyethyleneimine (PEI) through hydrogen-bonding to the gold surface and increased the stability of subsequent multilayers. PEI was directly adsorbed on the SPE surface. PEI is a short chain polymer and thence an efficient electron carrier, and being positively charged, it allows the formation of LBL structures with negatively charged enzymes. The multilayer formation of PEI(+)/GOx(-) was monitored by cyclic voltammetry, electrochemical impedance spectroscopy, and gravimetry. The influence of each enzymatic layer on the performance of the developed biosensor was analysed by fixed potential amperometric measurements.
  • Náhled
    ČlánekOtevřený přístuppeer-reviewedpublished
    Applicability of electrodes modified with composite layers of conducting polymers in electro- and bioelectroanalysis
    (Univerzita Pardubice, 2014) Socha, Ewelina; Krzyczmonik, Paweł; Skrzypek, Sławomira
    Obtaining modified electrodes is a response of electrochemistry to continuous development in areas such as technology, electronics, medicine, biology and many others. Modifying layers allow scientists to build electrodes with required properties such as for example: selectivity, stability, precision, durability, range of potentials etc. The aim of the studies was to modify the surface of gold and platinum with the layer of poly(3,4-ethylenedioxythiophene) (PEDOT) and polyaniline (PANI) doped with various organic acids and their salts. Additives such as p–toluenesulfonic acid (PTSA), dodecylbenzene-sulfonic acid (DBSA), poly(4-styrenesulfonic acid) (PSSH) and poly(4-lithium styrenesulfonic acid) (PSSLi) were used. The main application of these electrodes was the determination of ascorbic acid, uric acid and catecholamines (dopamine, epinephrine). Another modification covered the preparation of PEDOT/polyacrylic acid (PAA)/PSSLi layer with available free carboxyl groups and afterwards the immobilization of glucose oxidase via covalent bond through N-(3- dimethylaminopropyl)-N′-ethylcarbodiimide (WSC). The purpose of the research on selected modifications was to find electrodes that could be applied in electroanalysis as sensors to determine chosen biologically active compounds. Low capacity current, wide range of potentials, the ability to work in the broadest pH range, especially physiological pH was required. The third modification gave rise to the honeycomb structure with the increased area of electrode surface and the use of PEDOT/PAA/PSSLi allows us to immobilize enzyme.
  • Náhled
    ČlánekOtevřený přístuppeer-reviewedpublished
    Determination of insulin using a pretreated pencil graphite electrode
    (Univerzita Pardubice, 2014) Vu, Dai Long; Ertek, Bensu; Červenka, Libor; Dilgin, Yusuf
    In this paper, pretreated pencil graphite electrode (Pre-PGE) was used for the determination of insulin by anodic stripping differential pulse voltammetry (DPASV). The influences of the pretreatment procedures, pH values, accumulation potential and time on the signal enhancement of insulin were optimized, and a novel electrochemical method for the determination of insulin was described. The currents obtained from DPASV measurements at optimum conditions (phosphate buffer solution pH 7.0), accumulation time (60 seconds), applied potential 400 mV vs. Ag/AgCl/3.0 mol L−1 KCl) were linearly correlated with the concentration of insulin. Calibration curve was obtained for insulin concentrations in the range of 5.0-200.0×10-9 mol L−1 .The limit of detection was found to be 2.0×10-9 mol L−1.
  • Náhled
    ČlánekOtevřený přístuppeer-reviewedpublished
    Electrochemical sensor for histamine determination based on zinc oxide thin films electrodeposited on carbon paste electrodes
    (Univerzita Pardubice, 2014) Pekec, Bruna; Hauser, Susanne; Kalcher, Kurt; Ortner, Astrid
    Histamine, a biogenic amine and important mediator of inflammation was quantitatively analysed using electrochemical techniques. The sensor designed in this context based on carbon paste (CP) as electrode material and zinc oxide (ZnO) as modifier to increase the selectivity, due to the strong complex building tendency of the imidazole ring to metals. Using an alkaline electrolyte medium the oxidation potential was shifted from + 1.20 V in neutral medium to a less positive value of + 0.750 V vs. Ag/AgCl. A logarithmic correlation for a concentration range from 5 to 500 μg/mL could be found. The developed ZnO-CP based sensor, characterized by a precision (R.S.D.) of 5.8 % and an accuracy of 5.2 % was successfully tested in complex food matrix.
  • Náhled
    ČlánekOtevřený přístuppeer-reviewedpublished
    Voltammetric determination of Diazepam at meniscus-modified silver solid amalgam electrode
    (Univerzita Pardubice, 2014) Samiec, Petr; Fischer, Jan; Navrátilová, Zuzana
    Voltammetric methods for determination of Diazepam (DZ) were developed. Techniques differential pulse voltammetry and DC voltammetry were used for determination of DZ at meniscus-modified silver solid amalgam electrode (m-AgSAE). The effect of the pH on the intensity of signal of DZ was studied in a mixture of Britton-Robinson buffer + methanol (9:1) and 0.1 M NaOH + methanol (9:1); the optimal medium for analysis was a mixture of 0.1 M NaOH + methanol (9:1). The developed method has been tested on the determination of DZ in a sample of commercial drug (Diazepam).
  • Náhled
    ČlánekOtevřený přístuppeer-reviewedpublished
    Possibilities of voltammetric determination of pyridine herbicide picloram using boron-doped diamond electrodes
    (Univerzita Pardubice, 2014) Bandžuchová, Lenka; Švorc, Ľubomír; Vojs, Marian; Marton, Marián; Michniak, Pavol; Chýlková, Jaromíra
    Voltammetric behavior of a wide-spread used pyridine herbicide picloram (PCR) was investigated using two different types of boron-doped diamond working electrodes: commercial available and self-assembled. PCR provided one irreversible oxidation peak in an acidic medium occurring at very positive potential (about +1.5 V vs. Ag/AgCl/ 3 mol L−1 KCl) in both cases. 1 mol L−1 sulfuric acid was selected as the most suitable supporting electrolyte for electrochemical oxidation of PCR. Differential pulse voltammetric methodology was elaborated and its operating parameters were optimized to achieve the best analytical performance for determination of PCR. Both working electrodes provided high repeatability, wide linear concentration range and low limit of detection. Applicability of proposed method was verified by analysis of PCR in model samples of tap and natural waters and human urine, respectively.
  • Náhled
    ČlánekOtevřený přístuppeer-reviewedpublished
    On the performance of amperometric tyrosinase carbon paste biosensor in the presence of catechol, resorcinol, or hydroquinone
    (Univerzita Pardubice, 2014) Sýs, Milan; Metelka, Radovan; Vytřas, Karel
    This study was aimed to understand which substitution position of hydroxy groups on benzene ring is the most suitable for active site of enzyme tyrosinase, and also to determine if tyrosinase is a useful biological component for the development a biosensor based on carbon material for the determination of polyphenolic compounds in food samples. Electrochemical properties of diphenols (catechol, resorcinol, and hydroquinone) at bare carbon paste electrode (CPE) and CPE surface-modified with conductive copolymer Nafion and enzyme mushroom tyrosinase (CPE/Tyr/Nafion) were investigated using cyclic voltammetry and hydrodynamic amperometry.
  • Náhled
    ČlánekOtevřený přístuppeer-reviewedpublished
    Electrochemical behavior of triethanolamine at a carbon paste electrode
    (Univerzita Pardubice, 2014) Karastogianni, Sophia; Girousi, Stella
    In this article, the electrochemical behavior of triethanolimine is described with a carbon paste electrode. A differential pulse voltammetric method was also developed for the determination of triethanolamine as an application to electroanalysis at a carbon paste electrode. The resultant voltammograms have revealed the irreversible electrochemical process that can be utilized to quantify the substances of interest, for triethanolamine, for which the detection limit (3σ) was estimated to be 2.8 × 10−5 mol L−1.
  • Náhled
    ČlánekOtevřený přístuppeer-reviewedpublished
    Development of a laccase biosensor for determination of Phenolic micropollutants in surface waters
    (Univerzita Pardubice, 2014) Souza Gil, Eric de; Rezende, Stefani Garcia; Júnior, Eli José Miranda Ribeiro; Barcelos, Hernane Toledo; Scalize, Paulo Sérgio; Santiago, Mariangela Fontes; Quintino, Michelle Pereira; Somerset, Vernon Sydwill
    Laccase is a poliphenoloxidase enzyme that catalyzes the oxidation of phenolic compounds in the corresponding quinones. The current obtained in this redox process can be used for quantitative analysis. In this work, a carbon paste biosensor modified gluteraldehyde functionalized silica and an enzymatic extract of the Pycnoporus sanguineus fungi as a lacase source is proposed for phenol determination. The effect of carbon paste and electrolyte composition, pH from 3.0 to 8.0, start potential from 0.55 to 0.25 mV, scan rate from 5 to 25 mV s-1 and potential pulse amplitude from 10 to 60 mV on the differential pulse voltammetric response was investigated. A linear correlation of r² = 0.9946 was obtained for the phenol content (catechol) in the concentration range from 50 to 500 nmol L-1, with a detection limit of 30 nmol L-1. This biosensor was used for the determination of different kinds of phenolic compounds, presenting a better response for catechol.
  • Náhled
    ČlánekOtevřený přístuppeer-reviewedpublished
    New applications of carbon paste electrodes for determination of biologically active organic compoun
    (Univerzita Pardubice, 2014) Zima, Jiří; Barek, Jiří; Dejmková, Hana; Wang, Joseph
    In this paper, new electrochemical determinations of selected biologically active compounds are described employing various types of carbon paste electrodes (CPE) in batch voltammetric methods (differential pulse voltammetry (DPV), direct current voltammetry (DCV), and cyclic voltammetry (CV)) and in HPLC with electrochemical detection (HPLC-ED) utilizing amperometric CPE sensors. The results for determination of cymoxanil, famoxadone, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, chlortoluron, carboxin, triclosan, diafenthiuron, and propyl gallate are compared and discussed. Glassy carbon spherical microparticles were used as carbonaceous component of the paste. The limits of detection of some analytes were below 1·10-7 mol l-1 in both batch and flow methods. The newly developed methods of determination were applied to model samples of drinking and river water, soils, and practical samples of edible oil, toothpaste, soap, and toilet water.