Characterization of a D-Amino Acid Oxidase Microbiosensor for D-Serine Detection in the Central Nervous System

D-serine is a glial neuromodulator that is linked to several brain disorders such as schizophrenia, epilepsy, or stroke. We have developed an in situ D-serine microbiosensor that consists in a cylindrical platinum microelectrode covered with a layer of D-amino acid oxidase from the yeast R. gracilis. This enzyme converts D-serine into hydroxypyruvate, while producing hydrogen peroxide that, in turn, is oxidized by the electrode. Interferences by biogenic amines or ascorbic acid are greatly reduced by an additional membrane of poly-m-phenylene diamine. Our microbiosensor can monitor D-serine levels in vivo with a high temporal and spatial resolution. This method will make it possible to study D-serine dynamics in the central nervous system.