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.

Green synthesis of thermally stable Ag-rGO-CNT nano composite with high sensing activity

“…1)) of current vs. (enzyme-substrate affinity) of 7.7207±0.1 nA mM -1 value on account of its high I max (good enzyme loading) [45]. As the LRS is the most important parameter from an analytical perspective (sensitivity in the linear response region) as reported by [46] the most of the experiments described hereafter refer to this design: Naf/ Ag-rGO-CNTs /Glu-Tyr …”

Microelectrode Biosensors for in vivo Analysis of Brain Interstitial Fluid

“…However, most of the monomers used for pyrrole electropolymerization are not commercially available . An alternative is phenylenediamine, which can be readily polymerized into poly‐phenylenediamine, thereby facilitating the entrapment of glucose oxidase, glutamate oxidase, or D‐amino acid oxidase , although it is carcinogenic and must be handled with care.…”

Disk-Shaped Amperometric Enzymatic Biosensor for in Vivo Detection of d-serine

“…Overall, this biosensor provides a useful tool for detection of D-serine in any experimental situation where an amperometric probe could be applied. 36 cylindrical (125 × 1000) 404 971 825 48 ± 4 (n = 4) not available Wu et al 35 disk (3000) 7 068 583 14 400 2 ± 1 (n = 3) ∼100 Dominguez et al 44 cylindrical (3000 × 4000) 44 767 695 91 200 0.34 ± 0.001 (n = 10) 23 Nieh et al 45 disk (3000) 7 068 583 14 400 0.08 (n = 3) 2 a Diameter × Height. b The surface area ratio is defined as the ratio of the electroactive surface area of other biosensors to that of the experimental biosensor.…”