title: Development of an implantable D-serine biosensor for in vivo monitoring using mammalian D-amino acid oxidase on a poly (o-phenylenediamine) and Nafion-modified platinum-iridium disk electrode.
abstract: D-serine has been implicated as a brain messenger, promoting not only neuronal signalling but also synaptic plasticity. Thus, a sensitive tool for D-serine monitoring in brain is required to understand the mechanisms of D-serine release from glia cells. A biosensor for direct fixed potential amperometric monitoring of D-serine incorporating mammalian D-amino acid oxidase (DAAO) immobilized on a Nafion coated poly-ortho-phenylenediamine (PPD) modified Pt-Ir disk electrode was therefore developed. The combined layers of PPD and Nafion enhanced the enzyme activity and biosensor efficiency by approximately 2-fold compared with each individual layer. A steady state response time (t(90%)) of 0.7+/-0.1s (n=8) and limit of detection 20+/-1 nM (n=8) were obtained. Cylindrical geometry showed lower sensitivity compared to disk geometry (61+/-7 microA cm(-2) mM(-1), (n=4), R(2)=0.999). Interference by ascorbic acid (AA), the main interference species in the central nervous system and other neurochemical electroactive molecules was negligible. Implantation of the electrode and microinjection of D-serine into rat brain striatal extracellular fluid demonstrated that the electrode was capable of detecting D-serine in brain tissue in vivo.
authors: Pusat Pengajian Sains Kimia, Universiti Sains Malaysia, 11800 USM Pulau Pinang, Malaysia.
authors: Zainiharyati M
authors: ZM
authors: Zain
authors: Robert D
authors: RD
authors: O'Neill
authors: John P
authors: JP
authors: Lowry
authors: Kenneth W
authors: KW
authors: Pierce
authors: Mark
authors: M
authors: Tricklebank
authors: Aidiahmad
authors: A
authors: Dewa
authors: Sulaiman
authors: S
authors: Ab Ghani
mesh_terms: D000818:Animals; D003217:Conductometry / Q000295:instrumentation*; D003342:Corpus Striatum / Q000378:metabolism*; D003605:D-Amino-Acid Oxidase / Q000737:chemistry*; D004567:Electrodes, Implanted; D004800:Enzymes, Immobilized / Q000737:chemistry; D005465:Fluorocarbon Polymers / Q000737:chemistry; D006801:Humans; D007495:Iridium / Q000737:chemistry; D008297:Male; D010655:Phenylenediamines / Q000737:chemistry; D010984:Platinum / Q000737:chemistry; D019736:Prostheses and Implants; D051381:Rats; D017207:Rats, Sprague-Dawley; D012694:Serine / Q000032:analysis / Q000378:metabolism*
chemical_list: D004800:Enzymes, Immobilized; D005465:Fluorocarbon Polymers; D010655:Phenylenediamines; C530487:poly(o-phenylenediamine); C040402:perfluorosulfonic acid; D007495:Iridium; D012694:Serine; D010984:Platinum; C485958:Dao1 protein, mouse; D003605:D-Amino-Acid Oxidase