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(searched for: doi:10.4236/ojab.2013.21002)
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Nur Izzati Zakaria, Rosmawani Mohammad, Sharina Abu Hanifah, Azrilawani Ahmad
Published: 1 March 2022
Arabian Journal of Chemistry, Volume 15; https://doi.org/10.1016/j.arabjc.2021.103647

Nur Izzati Zakaria, , Sharina Abu Hanifah, Khadijah Hilmun Kamarudin, Azrilawani Ahmad
Published: 10 February 2021
Arabian Journal of Chemistry, Volume 14; https://doi.org/10.1016/j.arabjc.2021.103056

The publisher has not yet granted permission to display this abstract.
Published: 3 March 2017
by MDPI
Journal: Biosensors
Biosensors, Volume 7; https://doi.org/10.3390/bios7010013

Abstract:
A potentiometric enzyme biosensor is a convenient detector for quantification of urea concentrations in industrial processes, or for monitoring patients with diabetes, kidney damage or liver malfunction. In this work, poly(3-hexylthiophene-co-3-thiopheneacetic acid) (P(3HT-co-3TAA)) was chemically synthesized, characterized and spin-coated onto conductive indium tin oxide (ITO) glass electrodes. Urease (Urs) was covalently attached to the smooth surface of this copolymer via carbodiimide coupling. The electrochemical behavior and stability of the modified Urs/P(3HT-co-3TAA)/ITO glass electrode were investigated by cyclic voltammetry, and the bound enzyme activity was confirmed by spectrophotometry. Potentiometric response studies indicated that this electrode could determine the concentration of urea in aqueous solutions, with a quasi-Nernstian response up to about 5 mM. No attempt was made to optimize the response speed; full equilibration occurred after 10 min, but the half-time for response was typically <1 min.
Ruska Nenkova, Jiamin Wu, ,
Published: 31 December 2014
Analytical Letters, Volume 48, pp 1297-1310; https://doi.org/10.1080/00032719.2014.979364

Abstract:
Eleven glucose biosensors were prepared by cross-linking, entrapment, and layer-by-layer assembly to investigate the influence of these immobilization methods on performance. The effects of separate nanozeolites combined with magnetic nanoparticles and multiwalled carbon nanotubes in the enzyme composition on the performance of glucose biosensors were compared. Cyclic voltammetric studies were carried out on the biosensors. Acrylonitrile copolymer/nanozeolite/carbon nanotube and acrylonitrile copolymer/nanozeolite/magnetic nanoparticle electrodes prepared by a cross-linking method showed the highest electroactivity. These results indicated that a synergistic effect occurred when multiwalled carbon nanotubes, magnetic nanoparticles, and nanozeolites were combined that greatly improved the electron transfer ability of the sensors. Amperometric measurements by the glucose oxidase electrodes were obtained that showed that the acrylonitrile copolymer/nanozeolite/carbon nanotube electrode was the most sensitive (10.959 microamperes per millimolar). The lowest detection limit for this biosensor was 0.02 millimolar glucose, with a linear dynamic range up to 3 millimolar. The response after thirty days was 81 percent of the initial current.
B.H. Meshram, S.B. Kondawar, A.P. Mahajan, R.P. Mahore, D.K. Burghate
Journal of the Chinese Advanced Materials Society, Volume 2, pp 223-235; https://doi.org/10.1080/22243682.2014.935953

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