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A Complete Electroenzymatic Choline Microprobe Based on Nanostructured Platinum Microelectrodes and an IrOx On‐probe Reference Electrode
Author(s) -
Wang Bo,
Feng Lili,
Koo Bonhye,
Monbouquette Harold G.
Publication year - 2019
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/elan.201900039
Subject(s) - microelectrode , choline oxidase , electrode , ascorbic acid , materials science , nafion , biosensor , microprobe , platinum , selectivity , analytical chemistry (journal) , chemical engineering , nanotechnology , electrochemistry , chemistry , chromatography , organic chemistry , mineralogy , catalysis , food science , engineering , acetylcholinesterase , enzyme
A microelectrode array microprobe with a choline sensing site and an on‐probe reference electrode was constructed by depositing permselective polymer films and choline oxidase (ChOx) on one microelectrode, and iridium oxide (IrOx) on another, both of which were coated previously with a nanostructured Pt deposit. Scanning electron microscopy (SEM) of the nanostructured Pt layer revealed a unique pillar‐like, “nanograss” structure. Polyphenylenediamine (PPD) and Nafion were coated sequentially on the working ( i. e . sensing) electrode surface to serve as the permselective polymer films. The microsensor exhibited high sensitivity to choline (123±13 μA mM −1 cm −2 ), low detection limit (3.2±0.8 μM), and fast response time (3–5 s). The choline sensor also was tested at physiological concentrations of electroactive interfering species common to brain extracellular fluid ( i. e . ascorbic acid, dopamine, DOPA, and DOPAC) and showed excellent selectivity. Selectivity likely was aided by the relatively low potential of 0.35 V vs . IrOx that was made possible by the enhanced H 2 O 2 electrooxidation activity of the underlying nanostructured Pt‐coated working electrode. Thus, Pt “nanograss” appears to be an excellent electrode surface modification for creation of high performance electroenzymatic biosensors.