Antioxidants remove free radicals and inhibit the oxidation of oxygen-sensitive substances, which are of great significance in disease prevention and food preservative. Therefore, it is of great significance to establish a convenient, efficient and universal method for screening and evaluating antioxidant activity. In this study, Nitrogen-doped Graphene (N-G) with high conductivity and Chitosan (CS) with good film forming and stability were used as electrode substrate materials. And a ds-DNA/N-G@CS/GCE electrochemical biosensor for rapid evaluation of antioxidant activity was constructed by assembling ds-DNA and taking advantage of the signal difference between pre- and post-damage ds-DNA loading in Ru(NH3)6 3+ probe solution. N-G@CS with good electro-catalysis and high capacitance significantly improved the response signal of the sensor. At the same time, Square Wave Voltammetry (SWV) was used to optimize the conditions affecting the evaluation results of biosensors. The results showed that under the Fenton solution system with pH 7.0 and the ratio of Fe2+ to OH− 1:4, the biosensor has a high oxidation ds-DNA damage within 30 min The system can inhibit the damage of ds-DNA by adding antioxidants. Under optimized experimental conditions, composite yogurt and plain yogurt with weak antioxidant activity difference were evaluated by the constructed biosensor, and compared with L-ascorbic acid, the activity order was L-ascorbic acid > composite yogurt > plain yogurt. The results were consistent with the results of hydroxyl radical scavenging and ABTS+ radical scavenging experiments, and there was no significant difference between the three methods. This study not only provides a convenient and efficient method for the evaluation of antioxidant activity, but also provides strategies and technical support for the development of low-cost, highly sensitive and universal portable activity evaluation techniques.

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