title: A sensitive and stable amperometric nitrate biosensor employing Arabidopsis thaliana nitrate reductase.
abstract: Nitrate reductase (NR) from the plant Arabidopsis thaliana has been employed in the development of an amperometric nitrate biosensor that functions at physiological pH. The anion anthraquinone-2-sulfonate (AQ) is used as an effective artificial electron transfer partner for NR at a glassy carbon (GC) electrode. Nitrate is enzymatically reduced to nitrite and the oxidized form of NR is electrochemically reduced by the hydroquinone form of the mediator (AQH2). The GC/NR electrode shows a pronounced cathodic wave for nitrate reduction and the catalytic current increases linearly in the nitrate concentration range of 10-400 µM with a correlation coefficient of 0.989. Using an amperometric method, a low detection limit of 0.76 nM (S/N = 3) was achieved. The practical application of the present electrochemical biosensor was demonstrated by the determination of nitrate concentration in natural water samples and the results agreed well with a standard spectroscopic method.
authors.affiliation: School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, 4072, Australia.
authors.forename: Palraj
authors.initials: P
authors.lastname: Kalimuthu
authors.forename: Katrin
authors.initials: K
authors.lastname: Fischer-Schrader
authors.forename: Günter
authors.initials: G
authors.lastname: Schwarz
authors.forename: Paul V
authors.initials: PV
authors.lastname: Bernhardt
mesh_terms: D017360:Arabidopsis / Q000737:chemistry / Q000201:enzymology; D015374:Biosensing Techniques; D006873:Hydroquinones / Q000737:chemistry; D050901:Nitrate Reductase / Q000737:chemistry*; D009566:Nitrates / Q000737:chemistry / Q000302:isolation & purification*
chemical_list: D006873:Hydroquinones; D009566:Nitrates; D050901:Nitrate Reductase; C031927:hydroquinone