TY  - JOUR
AU  - Mehmeti, Eda
AU  - Stanković, Dalibor
AU  - Chaiyo, Sudkate
AU  - Zavašnik, Janez
AU  - Zagar, Kristina
AU  - Kalcher, Kurt
PY  - 2017
UR  - https://cherry.chem.bg.ac.rs/handle/123456789/2438
AB  - A reagentless third generation electrochemical glucose biosensor was fabricated based on wiring the template enzyme glucose oxidase (GOx) with graphene nanoribbons (GN) in order to create direct electron transfer between the co-factor (flavin adenine dinucleotide, FAD) and the electrode. The strategy involved: (i) isolation of the apo-enzyme by separating it from its co-enzyme; (ii) preparation of graphene nanoribbons (GN) by oxidative unzipping of multi-walled carbon nanotubes; (iii) adsorptive immobilization of GNs on the surface of a screen printed carbon electrode (SPCE); (iv) covalent attachment of FAD to the nanoribbons; (v) recombination of the apo-enzyme with the covalently bound FAD to the holoenzyme; and (vi) stabilization of the bio-layer with a thin membrane of Nafion. The biosensor (referred to as GN/FAD/apo-GOx/Nafion/SPCE) is operated at a potential of +0.475 V vs Ag/AgCl/{3 M KCl} in flow-injection mode with an oxygen-free phosphate buffer (pH 7.5) acting as a carrier. The signals are linearly proportional to the concentration of glucose in the range from 50 to 2000 mgai...L-1 with a detection limit of 20 mgai...L-1. The repeatability (10 measurements, at 1000 mgai...L-1 glucose) is +/- 1.4% and the reproducibility (5 sensors, 1000 mgai...L-1 glucose) is +/- 1.8%. The biosensor was applied to the determination of glucose in human serum.
PB  - Springer Wien, Wien
T2  - Microchimica Acta
T1  - Wiring of glucose oxidase with graphene nanoribbons: an electrochemical third generation glucose biosensor
VL  - 184
IS  - 4
SP  - 1127
EP  - 1134
DO  - 10.1007/s00604-017-2115-5
ER  - 

@article{
author = "Mehmeti, Eda and Stanković, Dalibor and Chaiyo, Sudkate and Zavašnik, Janez and Zagar, Kristina and Kalcher, Kurt",
year = "2017",
abstract = "A reagentless third generation electrochemical glucose biosensor was fabricated based on wiring the template enzyme glucose oxidase (GOx) with graphene nanoribbons (GN) in order to create direct electron transfer between the co-factor (flavin adenine dinucleotide, FAD) and the electrode. The strategy involved: (i) isolation of the apo-enzyme by separating it from its co-enzyme; (ii) preparation of graphene nanoribbons (GN) by oxidative unzipping of multi-walled carbon nanotubes; (iii) adsorptive immobilization of GNs on the surface of a screen printed carbon electrode (SPCE); (iv) covalent attachment of FAD to the nanoribbons; (v) recombination of the apo-enzyme with the covalently bound FAD to the holoenzyme; and (vi) stabilization of the bio-layer with a thin membrane of Nafion. The biosensor (referred to as GN/FAD/apo-GOx/Nafion/SPCE) is operated at a potential of +0.475 V vs Ag/AgCl/{3 M KCl} in flow-injection mode with an oxygen-free phosphate buffer (pH 7.5) acting as a carrier. The signals are linearly proportional to the concentration of glucose in the range from 50 to 2000 mgai...L-1 with a detection limit of 20 mgai...L-1. The repeatability (10 measurements, at 1000 mgai...L-1 glucose) is +/- 1.4% and the reproducibility (5 sensors, 1000 mgai...L-1 glucose) is +/- 1.8%. The biosensor was applied to the determination of glucose in human serum.",
publisher = "Springer Wien, Wien",
journal = "Microchimica Acta",
title = "Wiring of glucose oxidase with graphene nanoribbons: an electrochemical third generation glucose biosensor",
volume = "184",
number = "4",
pages = "1127-1134",
doi = "10.1007/s00604-017-2115-5"
}

Mehmeti, E., Stanković, D., Chaiyo, S., Zavašnik, J., Zagar, K.,& Kalcher, K.. (2017). Wiring of glucose oxidase with graphene nanoribbons: an electrochemical third generation glucose biosensor. in Microchimica Acta
Springer Wien, Wien., 184(4), 1127-1134.
https://doi.org/10.1007/s00604-017-2115-5

Mehmeti E, Stanković D, Chaiyo S, Zavašnik J, Zagar K, Kalcher K. Wiring of glucose oxidase with graphene nanoribbons: an electrochemical third generation glucose biosensor. in Microchimica Acta. 2017;184(4):1127-1134.
doi:10.1007/s00604-017-2115-5 .

Mehmeti, Eda, Stanković, Dalibor, Chaiyo, Sudkate, Zavašnik, Janez, Zagar, Kristina, Kalcher, Kurt, "Wiring of glucose oxidase with graphene nanoribbons: an electrochemical third generation glucose biosensor" in Microchimica Acta, 184, no. 4 (2017):1127-1134,
https://doi.org/10.1007/s00604-017-2115-5 . .

TY  - JOUR
AU  - Mehmeti, Eda
AU  - Stanković, Dalibor
AU  - Chaiyo, Sudkate
AU  - Šovrc, Ľubomír
AU  - Kalcher, Kurt
PY  - 2016
UR  - https://cherry.chem.bg.ac.rs/handle/123456789/1926
AB  - A carbon paste electrode bulk was modified with MnO2 and investigated for use as an electrochemical sensor for riboflavin (vitamin B-2) using differential pulse voltammetry (DPV). Riboflavin displays a well expressed oxidation peak at -0.15 V (versus Ag/AgCl) in solutions with a pH value of 2. Effects of pH value, pulse amplitude and pulse time were optimized by employing DPV. The signals obtained are linearly related to the concentrations of riboflavin in the range from 0.02 to 9 mu M. Other features include a 15 nM detection limit, and good reproducibility (+/- 3 %) and repeatability (+/- 2 %). Interferences by common compounds were tested, and the method was successfully applied to the determination of riboflavin in pharmaceutical formulations where is gave recoveries in the range from 95 to 97 %.
PB  - Springer Wien, Wien
T2  - Microchimica Acta
T1  - Manganese dioxide-modified carbon paste electrode for voltammetric determination of riboflavin
VL  - 183
IS  - 5
SP  - 1619
EP  - 1624
DO  - 10.1007/s00604-016-1789-4
ER  - 

@article{
author = "Mehmeti, Eda and Stanković, Dalibor and Chaiyo, Sudkate and Šovrc, Ľubomír and Kalcher, Kurt",
year = "2016",
abstract = "A carbon paste electrode bulk was modified with MnO2 and investigated for use as an electrochemical sensor for riboflavin (vitamin B-2) using differential pulse voltammetry (DPV). Riboflavin displays a well expressed oxidation peak at -0.15 V (versus Ag/AgCl) in solutions with a pH value of 2. Effects of pH value, pulse amplitude and pulse time were optimized by employing DPV. The signals obtained are linearly related to the concentrations of riboflavin in the range from 0.02 to 9 mu M. Other features include a 15 nM detection limit, and good reproducibility (+/- 3 %) and repeatability (+/- 2 %). Interferences by common compounds were tested, and the method was successfully applied to the determination of riboflavin in pharmaceutical formulations where is gave recoveries in the range from 95 to 97 %.",
publisher = "Springer Wien, Wien",
journal = "Microchimica Acta",
title = "Manganese dioxide-modified carbon paste electrode for voltammetric determination of riboflavin",
volume = "183",
number = "5",
pages = "1619-1624",
doi = "10.1007/s00604-016-1789-4"
}

Mehmeti, E., Stanković, D., Chaiyo, S., Šovrc, Ľ.,& Kalcher, K.. (2016). Manganese dioxide-modified carbon paste electrode for voltammetric determination of riboflavin. in Microchimica Acta
Springer Wien, Wien., 183(5), 1619-1624.
https://doi.org/10.1007/s00604-016-1789-4

Mehmeti E, Stanković D, Chaiyo S, Šovrc Ľ, Kalcher K. Manganese dioxide-modified carbon paste electrode for voltammetric determination of riboflavin. in Microchimica Acta. 2016;183(5):1619-1624.
doi:10.1007/s00604-016-1789-4 .

Mehmeti, Eda, Stanković, Dalibor, Chaiyo, Sudkate, Šovrc, Ľubomír, Kalcher, Kurt, "Manganese dioxide-modified carbon paste electrode for voltammetric determination of riboflavin" in Microchimica Acta, 183, no. 5 (2016):1619-1624,
https://doi.org/10.1007/s00604-016-1789-4 . .

TY  - JOUR
AU  - Mehmeti, Eda
AU  - Stanković, Dalibor
AU  - Chaiyo, Sudkate
AU  - Šovrc, Ľubomír
AU  - Ortner, Astrid
AU  - Kalcher, Kurt
PY  - 2016
UR  - https://cherry.chem.bg.ac.rs/handle/123456789/2259
AB  - A simple, sensitive, and economically viable electrochemical method for the determination of ajmalicine was developed. The procedure involves a glassy carbon electrode modified with gold nanoparticles (GCE/AuNPs). In the work presented here gold nanoparticles were attached to the glassy carbon electrode by adsorption. Cyclic voltammetry was used for the first time for the electrochemical characterization of ajmalicine and differential pulse voltammetry for its quantitative determination. Britton-Robinson buffer solution in a range of pH values served as supporting electrolyte. The experimental conditions were optimized and it was found that ajmalicine provided a well-defined oxidation peak at a potential of +0.8 V vs. Ag/AgCl (3 M KCl). The method for the determination of ajmalicine showed a dynamic range for concentrations from 5 to 50 A mu M with a detection limit of 1.7 A mu M, good repeatability (RSD of 1.4 %) and reproducibility (RSD of 2.5 %). The effect of possible interferents (yohimbine, reserpine) appeared to be negligible. The proposed procedure was successfully applied for the first time to the determination of ajmalicine in commercially available oral solutions for medical applications with results in good agreement with the declared content of ajmalicine. [GRAPHICS]
PB  - Springer Wien, Wien
T2  - Monatshefte Fur Chemie
T1  - Electrochemical determination of ajmalicine using glassy carbon electrode modified with gold nanoparticles
VL  - 147
IS  - 7
SP  - 1161
EP  - 1166
DO  - 10.1007/s00706-016-1741-7
ER  - 

@article{
author = "Mehmeti, Eda and Stanković, Dalibor and Chaiyo, Sudkate and Šovrc, Ľubomír and Ortner, Astrid and Kalcher, Kurt",
year = "2016",
abstract = "A simple, sensitive, and economically viable electrochemical method for the determination of ajmalicine was developed. The procedure involves a glassy carbon electrode modified with gold nanoparticles (GCE/AuNPs). In the work presented here gold nanoparticles were attached to the glassy carbon electrode by adsorption. Cyclic voltammetry was used for the first time for the electrochemical characterization of ajmalicine and differential pulse voltammetry for its quantitative determination. Britton-Robinson buffer solution in a range of pH values served as supporting electrolyte. The experimental conditions were optimized and it was found that ajmalicine provided a well-defined oxidation peak at a potential of +0.8 V vs. Ag/AgCl (3 M KCl). The method for the determination of ajmalicine showed a dynamic range for concentrations from 5 to 50 A mu M with a detection limit of 1.7 A mu M, good repeatability (RSD of 1.4 %) and reproducibility (RSD of 2.5 %). The effect of possible interferents (yohimbine, reserpine) appeared to be negligible. The proposed procedure was successfully applied for the first time to the determination of ajmalicine in commercially available oral solutions for medical applications with results in good agreement with the declared content of ajmalicine. [GRAPHICS]",
publisher = "Springer Wien, Wien",
journal = "Monatshefte Fur Chemie",
title = "Electrochemical determination of ajmalicine using glassy carbon electrode modified with gold nanoparticles",
volume = "147",
number = "7",
pages = "1161-1166",
doi = "10.1007/s00706-016-1741-7"
}

Mehmeti, E., Stanković, D., Chaiyo, S., Šovrc, Ľ., Ortner, A.,& Kalcher, K.. (2016). Electrochemical determination of ajmalicine using glassy carbon electrode modified with gold nanoparticles. in Monatshefte Fur Chemie
Springer Wien, Wien., 147(7), 1161-1166.
https://doi.org/10.1007/s00706-016-1741-7

Mehmeti E, Stanković D, Chaiyo S, Šovrc Ľ, Ortner A, Kalcher K. Electrochemical determination of ajmalicine using glassy carbon electrode modified with gold nanoparticles. in Monatshefte Fur Chemie. 2016;147(7):1161-1166.
doi:10.1007/s00706-016-1741-7 .

Mehmeti, Eda, Stanković, Dalibor, Chaiyo, Sudkate, Šovrc, Ľubomír, Ortner, Astrid, Kalcher, Kurt, "Electrochemical determination of ajmalicine using glassy carbon electrode modified with gold nanoparticles" in Monatshefte Fur Chemie, 147, no. 7 (2016):1161-1166,
https://doi.org/10.1007/s00706-016-1741-7 . .