8/2013-14 Sensing in Electroanalysis
https://hdl.handle.net/10195/56677
2024-03-30T05:06:40ZDevelopment and characterization of layer-by-layer biosensors based on PEI(+)/GOx(-) layers using label-free methods
https://hdl.handle.net/10195/58412
Development and characterization of layer-by-layer biosensors based on PEI(+)/GOx(-) layers using label-free methods
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.
2014-01-01T00:00:00ZApplicability of electrodes modified with composite layers of conducting polymers in electro- and bioelectroanalysis
https://hdl.handle.net/10195/58411
Applicability of electrodes modified with composite layers of conducting polymers in electro- and bioelectroanalysis
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.
2014-01-01T00:00:00ZDetermination of insulin using a pretreated pencil graphite electrode
https://hdl.handle.net/10195/58410
Determination of insulin using a pretreated pencil graphite electrode
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.
2014-01-01T00:00:00ZElectrochemical sensor for histamine determination based on zinc oxide thin films electrodeposited on carbon paste electrodes
https://hdl.handle.net/10195/58409
Electrochemical sensor for histamine determination based on zinc oxide thin films electrodeposited on carbon paste electrodes
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.
2014-01-01T00:00:00Z