title: Highly sensitive flow-biosensor for toxic phenolic compounds using tyrosinase and acridine orange-adsorbed carbon felt.
abstract: Tyrosinase (TYR, EC 1.14.18.1) was physically adsorbed onto a carbon felt (CF) together with acridine orange (AO). Coadsorption of AO was essential to prevent the denaturation of the TYR at the CF surface. The resulting TYR and AO-coadsorbed CF (TYR/AO-CF) was successfully utilized as a detection unit of novel and highly sensitive amperometric flow-biosensor for toxic chlorophenol compounds. Standard solutions of phenolic compounds (200 μL) were injected, and the cathodic peak currents due to the reduction current of o-quinones produced by the TYR-catalyzed oxidation (phenolase activity) were detected at the applied potential of -50 mV vs. Ag/AgCl. In this reaction, the electrochemically generated catechol compounds from o-quinones are re-oxidized repeatedly by catecholase activity of the TYR, leading to a sufficient amplified signal. The TYR/AO-CF exhibited much higher selectivity toward p-chlorophenol as compared with other chlorophenol compounds. When 0.1 mol/L phosphate buffer (pH 7.0) was used as a carrier at flow rate of 3.0 mL/min, cathodic peaks for p-chlorophenol was linear in the concentration range between 0.1 and 10 μmol/L (sensitivity: 1.41(mA·L)/mmol) with sampling rate (30 samples/h), and the detection limit of p-chlorophenol was found to be 2.13 × 10(8) mol/L (S/N = 3. The ratio of signal and noise is 3). The TYR/AO-CF kept more than 80% of original activity after the storage in 0.1 mol/L phosphate buffer (pH 7.0) containing 0.2 mmol/L AO at 4°C.
authors.affiliation: Department of Material Science and Engineering, Saitama Institute of Technology, Fukaya 369-0293, Japan; School of Chemical Engineering, University of Science and Technology Liaoning, Anshan 114501, China.
authors.forename: Yue
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Material Science and Engineering, Saitama Institute of Technology, Fukaya 369-0293, Japan; Department of Life Science and Green Chemistry, Saitama Institute of Technology, Fukaya 369-0293, Japan.
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Hasebe
mesh_terms: D000165:Acridine Orange / Q000737:chemistry*; D000327:Adsorption; D055162:Biocatalysis; D015374:Biosensing Techniques / Q000379:methods*; D002244:Carbon / Q000737:chemistry*; D000077482:Carbon Fiber; D002733:Chlorophenols / Q000737:chemistry; D004563:Electrochemistry; D017022:Flow Injection Analysis; D006900:Hydroxylation; D008855:Microscopy, Electron, Scanning; D014442:Monophenol Monooxygenase / Q000378:metabolism*; D010636:Phenols / Q000032:analysis* / Q000633:toxicity*; D012996:Solutions; D013379:Substrate Specificity
chemical_list: D000077482:Carbon Fiber; D002733:Chlorophenols; D010636:Phenols; D012996:Solutions; C029107:4-chlorophenol; D002244:Carbon; D014442:Monophenol Monooxygenase; D000165:Acridine Orange