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Amperometric Tyrosinase Biosensor Based on Carbon Nanotube-Doped Sol-Gel-Derived Zinc Oxide–Nafion Composite Films



A highly sensitive amperometric tyrosinase biosensor has been developed based on mesoporous composite films of carbon nanotube (CNT)–ZnO–Nafion composite film encapsulating tyrosinase on a glassy carbon electrode. Due to the mesoporous nature (diameter: 3.17 nm) of the composite film, the biosensor exhibits very fast response time of 2 s. The present biosensor shows an excellent sensitivity of 766 mA/M and a detection limit of 4.7×10−8 M (S/N=3) for phenol. The biosensor retains 88 % of its initial activity after 2 weeks of storage in 50 mM phosphate buffer at pH 7.0. The present biosensor exhibits good recovery for the spiked phenol in an industrial waste water sample.