title: Amperometric nitrate biosensor based on Carbon nanotube/Polypyrrole/Nitrate reductase biofilm electrode.
abstract: This study describes the construction and characterization of an amperometric nitrate biosensor based on the Polypyrrole (PPy)/Carbon nanotubes (CNTs) film. Nitrate reductase (NR) was both entrapped into the growing PPy film and chemically immobilized via the carboxyl groups of CNTs to the CNT/PPy film electrode. The optimum amperometric response for nitrate was obtained in 0.1 M phosphate buffer solution (PBS), pH 7.5 including 0.1 M lithium chloride and 7 mM potassium ferricyanide with an applied potential of 0.13 V (vs. Ag/AgCl, 3 M NaCl). Sensitivity was found to be 300 nA/mM in a linear range of 0.44-1.45 mM with a regression coefficient of 0.97. The biosensor response showed a higher linear range in comparison to standard nitrate analysis methods which were tested in this study and NADH based nitrate biosensors. A minimum detectable concentration of 0.17 mM (S/N=3) with a relative standard deviation (RSD) of 5.4% (n=7) was obtained for the biosensor. Phenol and glucose inhibit the electrochemical reaction strictly at a concentration of 1 μg/L and 20 mg/L, respectively. The biosensor response retained 70% of its initial response over 10 day usage period when used everyday.
authors.affiliation: Department of Environmental Engineering, Gebze Institute of Technology, 41400 Gebze, Kocaeli, Turkey.
authors.forename: Faruk
authors.initials: F
authors.lastname: Can
authors.forename: Seyda
authors.initials: S
authors.lastname: Korkut Ozoner
authors.forename: Pinar
authors.initials: P
authors.lastname: Ergenekon
authors.forename: Elif
authors.initials: E
authors.lastname: Erhan
mesh_terms: D018441:Biofilms; D015374:Biosensing Techniques / Q000295:instrumentation* / Q000379:methods*; D002021:Buffers; D004563:Electrochemistry / Q000379:methods; D004800:Enzymes, Immobilized / Q000737:chemistry; D005947:Glucose / Q000737:chemistry; D057230:Limit of Detection; D037742:Nanotubes, Carbon / Q000737:chemistry*; D050901:Nitrate Reductase / Q000737:chemistry*; D009566:Nitrates / Q000032:analysis*; D019800:Phenol / Q000737:chemistry; D011108:Polymers / Q000737:chemistry; D011758:Pyrroles / Q000737:chemistry; D012680:Sensitivity and Specificity
chemical_list: D002021:Buffers; D004800:Enzymes, Immobilized; D037742:Nanotubes, Carbon; D009566:Nitrates; D011108:Polymers; D011758:Pyrroles; C067635:polypyrrole; D019800:Phenol; D050901:Nitrate Reductase; D005947:Glucose