Manganese-doped carbon nanospheres with robust peroxidase-like activity for the colorimetric detection of total antioxidant capacity

Abstract

Total antioxidant capacity (TAC) assessment is vital for evaluating food nutritional quality, yet conventional methods face limitations in complex matrices, efficiency, and environmental robustness. To address this, we synthesized manganese-doped porous carbon nanospheres (Mn@CNS), which feature a high density of uniformly distributed diverse catalytic sites, creating an efficient peroxidase-like nanozyme for sensitive colorimetric detection of TAC. Kinetic analysis revealed that Mn@CNS had strong affinities for both 3,3′,5,5′-tetramethylbenzidine and H₂O₂ substrates, with K_m values of 0.15 mM and 14.63 mM, respectively. This allowed us to establish an effective colorimetric detection platform for the rapid and sensitive identification of ascorbic acid with a low detection limit of 0.17 μM. Furthermore, we used cysteine, glutathione, ferulic acid, caffeic acid, quercetin and (+)-α-tocopherol to validate the efficacy of Mn@CNS in antioxidant assessment. This assay has successfully evaluated TAC in real samples, highlighting its potential for the rapid, cost-effective, on-site detection of TAC.