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Bioelectrochemistry. 2018 Jun;121:142-150. doi: 10.1016/j.bioelechem.2018.01.009. Epub 2018 Jan 31.

Simultaneous measurements of ascorbate and glutamate in vivo in the rat brain using carbon fiber nanocomposite sensors and microbiosensor arrays.

Author information

1
Faculty of Pharmacy, University of Coimbra, 3000-548 Coimbra, Portugal.
2
Center for Neuroscience and Cell Biology, University of Coimbra, 3004-517 Coimbra, Portugal.
3
Faculty of Pharmacy, University of Coimbra, 3000-548 Coimbra, Portugal; Center for Neuroscience and Cell Biology, University of Coimbra, 3004-517 Coimbra, Portugal.
4
Department of Neuroscience, Center for Microelectrode Technology, University of Kentucky, Lexington, USA.
5
Faculty of Pharmacy, University of Coimbra, 3000-548 Coimbra, Portugal; Center for Neuroscience and Cell Biology, University of Coimbra, 3004-517 Coimbra, Portugal. Electronic address: rbarbosa@ff.uc.pt.

Abstract

Nanocomposite sensors consisting of carbon fiber microelectrodes modified with Nafion® and carbon nanotubes, and ceramic-based microelectrode biosensor arrays were used to measure ascorbate and glutamate in the brain with high spatial, temporal and chemical resolution. Nanocomposite sensors displayed electrocatalytic properties towards ascorbate oxidation, translated into a negative shift from +0.20V to -0.05V vs. Ag/AgCl, as well as a significant increase (10-fold) of electroactive surface area. The estimated average basal concentration of ascorbate in vivo in the CA1, CA3 and dentate gyrus (DG) sub regions of the hippocampus were 276±60μM (n=10), 183±30μM (n=10) and 133±42μM (n=10), respectively. The glutamate microbiosensor arrays showed a high sensitivity of 5.3±0.8pAμM-1 (n=18), and LOD of 204±32nM (n=10), and t50% response time of 0.9±0.02s (n=6) and high selectivity against major interferents. The simultaneous and real-time measurements of glutamate and ascorbate in the hippocampus of anesthetized rats following local stimulus with KCl or glutamate revealed a dynamic interaction between the two neurochemicals.

KEYWORDS:

Ascorbate; Carbon nanotubes; Glutamate; In vivo monitoring; Microelectrode arrays

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