Analytical Sciences

A Tyrosinase Biosensor Based on ZnO Nanorod Clusters/Nanocrystalline Diamond Electrodes for Biosensing of Phenolic Compounds

Jianwen ZHAO,* Jinfang ZHI,** Yanli ZHOU,*** and Wenbin YAN*

*College of Chemistry and Chemical Engineering, Jishou University, Jishou, Hunan 416000, P. R. China
**Laboratory of Organic Optoelectronic Functional Materials and Molecular Engineering, Technical Institute of Physics and Chemistry & Graduate University of Chinese Academy of Sciences, No. 2, Beiyitiao, Zhong-guan-cun, Haidian, Beijing 100080, P. R. China
***Deparment of Chemistry, Shangqiu Normal University, Shangqiu, Henan 476000, P. R. China

An amperometric biosensor was constructed by using ZnO nanorod clusters as platforms for immobilizing tyrosinase on the nanocrystalline diamond (NCD) electrodes. The results showed that ZnO nanorod clusters provided an advantageous microenvironment due to their favorable isoelectric point (IEP) for tyrosinase loading; immobilized tyrosinase generally retained its activity. The tyrosinase/ZnO/NCD electrode showed a linear response range of 1 − 210 and sensitivity of 179.9 μA mmol⁻¹ cm⁻² for p-cresol. The corresponding values were 1 − 190 and 90.2 for phenol, and 1 − 250 and 121.3 for 4-chlorophenol. The low detection limits were estimated to be 0.2 μM for p-cresol, 0.5 μM for phenol, and 0.4 μM for 4-chlorophenol (S/N = 3). The prepared enzyme electrode could keep 85% of its original activity after intermittent use for 4 weeks when stored in a dry state at 277 K. Therefore, the ZnO nanorod cluster thin films have potential applications as platforms to immobilize other enzymes and bioactive molecules in biosensors.

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