D-serine is the major D-amino acid in the mammalian central nervous system. As the dominant co-agonist of the endogenous synaptic NMDA receptor, D-serine plays a role in synaptic plasticity, learning, and memory. Alterations in D-serine are linked to neuropsychiatric disorders including schizophrenia. Thus, it is of increasing interest to monitor the concentration of D-serine in vivo as a relevant player in dynamic neuron-glia network activity. Here we present a procedure for amperometric detection of D-serine with self-referencing ceramic-based microelectrode arrays (MEAs) coated with D-amino acid oxidase from the yeast Rhodotorula gracilis (RgDAAO). We demonstrate in vitro D-serine recordings with a mean sensitivity of 8.61 ± 0.83 pA/µM to D-serine, a limit of detection (LOD) of 0.17 ± 0.01 µM, and a selectivity ratio of 80:1 or greater for D-serine over ascorbic acid (mean ± SEM; n = 12) that can be used for freely moving studies.

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Published in Biosensors, v. 8, issue 1, 20, p. 1-11.

© 2018 by the authors.

This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

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This work was supported by Deutsche Forschungsgemeinschaft SFBTR654 Plasticity and Sleep (TPA06) and Deutsche Forschungsgemeinschaft SPP1665 (MA2053/4-2).

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The following are available online at https://www.mdpi.com/2079-6374/8/1/20/s1, Figure S1: In vitro calibration of one D-serine detecting Microelectrode Array (MEA) using 1 mM D-serine challenges, Figure S2: Linearity (R2) curve obtained from the calibration of the RgDAAO coated D-serine detecting MEA depicted in Figure 2, Table S1: In vitro calibration measurements for the RgDAAO coated D-serine detecting MEAs using final concentrations of 1 µM D-serine in the solution media (n = 5; mean ± SEM), Table S2: In vitro calibration measurements obtained from the calibration of the RgDAAO coated D-serine detecting MEA depicted in Figure 2.

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