Analytical Sciences

An Amperometric Biosensor Based on Ascorbate Oxidase Immobilized in Poly(3,4-ethylenedioxythiophene)/Multi-Walled Carbon Nanotubes Composite Films for the Determination of L-Ascorbic Acid

Ming LIU,*,** Yangping WEN,*,** Jingkun XU,* Haohua HE,** Dong LI,*,** Ruirui YUE,* and Guodong LIU***

*Jiangxi Key Laboratory of Organic Chemistry, Jiangxi Science and Technology Normal University, Nanchang 330013, China
**Key Laboratory of Crop Physiology, Ecology and Genetic Breeding, Ministry of Education, Key Laboratory of Physiology, Ecology and Cultivation of Double Cropping Rice, Ministry of Agriculture, Jiangxi Agricultural University, Nanchang 330045, China
***School of Communication and Electronics, Jiangxi Science and Technology Normal University, Nanchang 330013, China

An amperometric L-ascorbic acid (AA) biosensor fabricated by immobilizing ascorbate oxidase (AO) in poly(3,4-ethylenedioxythiophene) (PEDOT) and multi-walled carbon nanotubes (MWCNTs) composite films was reported for the first time. The entrapment of AO in PEDOT/MWCNTs composite films was performed during an electrochemical polymerization process. The influence of various experimental conditions was examined for determining the optimum analytical performance. The response of the biosensor towards AA under the optimized conditions is linear from 0.05 to 20 mM with a detection limit of 15 μM (S/N = 3). The biosensor shows a response time of 20 s and a sensitivity of 23.95 mA M⁻¹ cm⁻². The apparent Michaelis–Menten constant (K_m) and apparent activation energy (E_a) are 19.5 mM and 21 kJ mol⁻¹, respectively. Moreover, the biosensor exhibits good anti-interferent ability, good reproducibility and remarkable storage stability.

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