Voltammetric determination of folic acid at physiological pH values by using a glassy carbon electrode modified with a multilayer composite consisting of polyoxometalate (H8P2Mo16V2O62) and reduced graphene oxide and prepared via layer-by-layer self-assembly and in-situ photoreduction

• Published in: Mikrochimica acta (1966) Vol. 184; no. 11; pp. 4295 - 4303
• Main Authors: Xu, Hengbin, Bai, Zhenyuan, Wang, Guangning, O’Halloran, Kevin P., Tan, Lichao, Pang, Haijun, Ma, Huiyuan
• Format: Journal Article
• Language: English
• Published: Vienna Springer Vienna 01.11.2017; Springer; Springer Nature B.V
• Subjects: Analytical Chemistry; Catalytic activity; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Dopamine; Electrical measurement; Electrodes; Electrons; Folic acid; Glassy carbon; Graphene; Graphite; Hydrogen-ion concentration; Microengineering; Nanochemistry; Nanotechnology; Original Paper; Oxidation; Particulate composites; Photocatalysis; Photochemistry; Physiology; Polyethyleneimine; Self-assembly; Sensors; Spectrum analysis; Uric acid; Vanadium; Voltammetry; X-ray spectroscopy; Cyclic voltammetry; Dopamine; Human serum samples; Electrochemistry; Hexacyanoferrrate; Carbon-based material; Uric acid; Differential pulse voltammetry; Electrochemical impedance spectroscopy; Sensor
• ISSN: 0026-3672; 1436-5073
• DOI: 10.1007/s00604-017-2447-1

Vanadium-substituted polyoxometalate clusters of type H 8 P 2 Mo 16 V 2 O 62 and reduced graphene oxide (rGO) were incorporated into a multilayer composite film via combining layer-by-layer self-assembly (using polyethyleneimine) and in-situ UV photoreduction. The growth of the multilayer film was monitored by UV-vis spectroscopy. The UV-induced conversion of graphene oxide to rGO in the multilayer film is due to the photocatalytic activity of P 2 Mo 16 V 2 and was proven by X-ray photoelectron spectroscopy. The material was placed on a glassy carbon electrode (GCE) where it displayed good electrocatalytic activity towards oxidation of folic acid (FA) as demonstrated by cyclic voltammetry and differential pulse voltammetry. The modified GCE (best operated at a working voltage of 0.75 V vs Ag/AgCl and a scan rate of 50 mV s −1 ) compared to films containing either P 2 Mo 16 V 2 or rGO only. The effects of the number of bilayers and of pH values on the electro-oxidation were investigated. The modified GCE was applied to selective determination of FA even in the presence of dopamine (DA) and uric acid (UA) at physiological pH. In fact, the modified GCE may also be applied to the simultaneous determination of DA, UA and FA. The amperometric response to FA increases linearly in the 10 nM to 0.8 mM FA concentration range, with a 0.28 nM detection limit. The sensor was successfully applied to the determination of FA in spiked human serum samples. Graphical abstract Schematic presentation of a multilayer composite film based on polyoxometalate and graphene was successfully constructed by combining layer-by-layer self-assembly and in situ photoreduction. It was used to selective determination of folic acid in the presence of dopamine and uric acid at physiological pH.