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

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) = 58.199C_H2O2+5.825 (C_H2O2 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.