Effect of Process Parameters on Electrochemical Performance of a Glutamate Microbiosensor

The effect of process parameters on the electrochemical performance of a glutamate (Glu) microbiosensor was studied. Glu is a major excitatory neurochemical that is essential for regulation of several brain functions. Glu dysregulation is associated with several neuropathological conditions such as epilepsy, Parkinson's and Alzheimer's disease. Here, an enzymatic microbiosensor in the form of a ceramic-shank substrate enabled platinum (Pt) microelectrode array (MEA) was employed to investigate the effect of key process parameters such as MEA surface cleaning methods, the effects of GluOx concentration, GluOx loading and size-exclusion layer thicknesses on Glu sensitivity and selectivity towards common interferents. A two-step cleaning procedure demonstrated a 57.4% increase in hydrogen peroxide sensitivity, which is due to 80-fold and 2-fold reductions respectively in the charge transfer resistances of the Pt microelectrode grains and grain boundaries. The microbiosensor demonstrated an excellent combination of sensitivity (530 +/- 34 nA cm(-2)mu M-1), selectivity (841 +/- 54) and long-term stability (2 months). These results provide a detailed account of changes in electrochemical properties and sensitivities of Pt microelectrodes toward peroxide, the rationale for choosing a higher GluOx concentration (0.4 U/mu l) instead of 0.1 U/mu l, which is the most commonly used concentration in the literature and recommendations on the enzyme loading and placement of size-exclusion coatings and their deposition conditions, which significantly affects the biosensor performance. (c) 2020 The Electrochemical Society (ECS). Published on behalf of ECS by IOP Publishing Limited.