Journal
SENSORS AND ACTUATORS B-CHEMICAL
Volume 216, Issue -, Pages 614-621Publisher
ELSEVIER SCIENCE SA
DOI: 10.1016/j.snb.2015.04.066
Keywords
Amperometric glutamate biosensor; Screen-printed; Multiwalled carbon nanotubes (MWCNTs); Reagentless
Funding
- University of the West of England, Bristol
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A screen printed carbon electrode (SPCE) containing the electrocatalyst Meldola's Blue (MB) has been investigated as the base transducer for a reagentless glutamate biosensor. The biopolymer chitosan (CHIT) and multiwalled carbon nanotubes (MWCNTs) were used to encapsulate the enzyme glutamate dehydrogenase (GLDH) and the co-factor nicotinamide adenine dinucleotide (NAD(+)). The biosensor was fabricated by sequentially depositing the components on the surface of the transducer (MB-SPCE) in a layer-by-layer process, details of which are included in the paper. Each layer was optimised to construct the reagentless device. The biosensor was used in conjunction with amperometry in stirred solution using an applied potential of +0.1 V (vs. Ag/AgCl). Optimum conditions for the analysis of glutamate were found to be: temperature, 35 degrees C; phosphate buffer, pH 7 (0.75 mM, containing 0.05 M NaCl). The linear range of the reagentless biosensor was found to be 7.5-105 mu M, and limit of detection was found to be 3 mu M (based on n = 5, CV: 8.5% based on three times signal to noise) and the sensitivity was 0.39 nA/mu M (+0.025, coefficient of variation (CV) of 6.37%, n = 5). The response time of the biosensor was 20-30 s. A food sample was analysed for monosodium glutamate (MSG). The endogenous content of MSG was 90.56 mg/g with a CV of 7.52%. The reagentless biosensor was also used to measure glutamate in serum. The endogenous concentration of glutamate was found to be 1.44 mM (n = 5), CV: 8.54%. The recovery of glutamate in fortified serum was 104% (n = 5), CV of 2.91%. (C) 2015 Elsevier B.V. All rights reserved.
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