Determination of Antioxidant Capacity by Using Xanthine Oxidase Bioreactor Coupled with Flow‐through H₂O₂ Amperometric Biosensor

Abstract

A new flow system for antioxidant capacity (AOC) estimation, consisting of a bioreactor, containing immobilized xanthine oxidase (XOD), coupled with a H 2 O 2 amperometric biosensor, based on Os-wired horseradish peroxidase, was developed. The H 2 O 2 , resulting from the enzymatic reaction between xanthine (XA) and XOD, was amperometrically monitored at À0.1 V vs. Ag/AgCl/KCl sat , in order to avoid the electrochemical interferences. Two protocols were used to perform the AOC evaluation: "steady-state", when the antioxidant (AOX) was injected in the XA flow, and "transient state", when XA and AOX were simultaneously injected in the carrier flow. The AOC of some commercial beverages were evaluated and compared with those obtained with 2,2-diphenyl-1-picrylhydrazyl radical and Folin-Ciocalteu methods.

Electrochemical Methods for Total Antioxidant Capacity and its Main Contributors Determination: A review

“…The H 2 O 2 resulting from the enzymic xanthine was amperometrically monitored at -0.1 V vs. Ag/AgCl/KCl sat, and it was reported that this potential value applied avoided interferences. The antioxidant capacities of the analysed commercial beverages were consistent with those furnished by DPPH· and Folin-Ciocalteu assays [123].…”

Determination of the Antioxidant Capacity of Red Fruits by Miniaturized Spectrophotometry Assays

“…2 However, in recent years, a great effort has been done in the use of more sophisticated and precise bioanalytical methods such as those based on electrochemical sensors and biosensors, in order to improve the detection performance. 8 In general, spectrophotometric techniques are simple, rapid and not expensive, which probably explains their widespread use in antioxidant screening. In turn, spectrometric techniques rely on the reaction of a radical, radical cation or complex with an antioxidant molecule capable of HAT and/or SET.…”

Electrochemical Biosensors for the Determination of the Antioxidant Capacity in Foods and Beverages Based on Reactive Oxygen Species

“…Nevertheless, this biosensor was not used in the analysis of food samples. On the other hand, their collaborators developed a flow system for the antioxidant capacity estimation consisting of a bioreactor with immobilized XOD (for the generation of O 2 -radicals) coupled with a H 2 O 2 amperometric biosensor [56]. The bioreactor was constructed using Teflon® tubing containing XOD immobilized on cyanogen bromideactivated Sepharose 4B gel, silica gel or controlled-pore glass.…”