title: Amperometric microbial biosensor for p-nitrophenol using Moraxella sp.-modified carbon paste electrode.
abstract: An amperometric microbial biosensor for highly specific, sensitive and rapid quantitative determination of p-nitrophenol was developed. The biosensor takes advantage of the ability of Moraxella sp. to specifically degrade p-nitrophenol to hydroquinone, a more electroactive compound than p-nitrophenol. The electrochemical oxidation current of hydroquinone formed in biodegradation of p-nitrophenol was measured at Moraxella sp.-modified carbon paste electrode and correlated to p-phenol concentrations. The optimum response was realized by electrode constructed using 15 mg of dry cell weight per 1 g of carbon paste and operating at 0.3 V (versus Ag/AgCl reference) in pH 7.5, 20 mM sodium phosphate buffer. Operating at these optimum conditions the biosensor had excellent selectivity against phenol derivatives and was able to measure as low as 20 nM (2.78 ppb) p-nitrophenol with very good accuracy and reproducibility. The biosensor was stable for approximately 3 weeks when stored at 4 degrees C. The applicability of the biosensor to measure p-nitrophenol in lake water was demonstrated.
authors.affiliation: Department of Chemical and Environmental Engineering, University of California, Riverside, CA 92521, USA.
authors.forename: Priti
authors.initials: P
authors.lastname: Mulchandani
authors.forename: Carlos M
authors.initials: CM
authors.lastname: Hangarter
authors.forename: Yu
authors.initials: Y
authors.lastname: Lei
authors.forename: Wilfred
authors.initials: W
authors.lastname: Chen
authors.forename: Ashok
authors.initials: A
authors.lastname: Mulchandani
mesh_terms: D001681:Biological Assay / Q000295:instrumentation / Q000379:methods; D015374:Biosensing Techniques / Q000295:instrumentation* / Q000379:methods; D002244:Carbon / Q000737:chemistry*; D004563:Electrochemistry / Q000295:instrumentation* / Q000379:methods; D004784:Environmental Monitoring / Q000295:instrumentation / Q000379:methods; D004867:Equipment Design; D019544:Equipment Failure Analysis; D008839:Microelectrodes; D009016:Moraxella / Q000187:drug effects*; D009596:Nitrophenols / Q000032:analysis* / Q000494:pharmacology*; D009824:Ointments; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D009596:Nitrophenols; D009824:Ointments; D014874:Water Pollutants, Chemical; D002244:Carbon; C024836:4-nitrophenol