A novel cell-based electrochemical biosensor based on MnO2 catalysis for antioxidant activity evaluation of anthocyanins.

The rapid, efficient, and objective evaluation of active antioxidant components is of great significance for the basic research of natural products and food quality. In this work, a three-dimensional (3D) cell culture system-based electrochemical biosensor for H2O2 detection based on the relationship between the H2O2 extracellular level and the current signal response was developed, which could be used for evaluating the antioxidant activity of active compounds. To increase the analytical selectivity and the response specificity, an A549 cells/hydrogel@carbon nanofibers (CNFs)/manganese dioxide nanowires (MnO2NWs)/gold nanoparticles (AuNPs)-modified electrochemical biosensor was successfully prepared based on the catalytic reaction between the response of H2O2 and MnO2 to the current signal. Under the optimized modification parameters of the working electrode surface, a good linear correlation was found between the oxidation peak current (Ip) value and the H2O2 concentration induced by paraquat. The linear equation was Ip(μA) = 58.199CH2O2+5.825 (CH2O2 for H2O2 concentration) with R2 = 0.993, and the detection limit of H2O2 was 0.02 μM, which indicated high sensitivity, satisfactory reproducibility, and stability of this method. The biosensor was successfully used to evaluate and grade the antioxidant activity of 16 anthocyanins and their glycosidic derivatives, indicating the feasibility of this method for the antioxidant evaluation of natural products. This proposed method provides a new way for evaluating the in vitro efficacy of natural products based on their physiological activities and for designing a new sensing platform.