Highly efficient bimetallic Ru-Co nanofibers-based peroxidase-like nanozyme for total antioxidant capacity detection

Bimetallic Ru-Co nanofibers (NFs) are successfully fabricated via an electrospinning technique coupled with thermal calcination and hydrogen reduction treatment. The optimized fibrous Ru 3 -Co 7 nanozyme demonstrates exceptional peroxidase (POD)-like activity, capable of oxidizing the chromogenic substrate 3,3′,5,5′-tetramethylbenzidine (TMB) by hydrogen peroxide (H 2 O 2 ) to generate oxidized TMB (oxTMB), yielding a characteristic blue response. Capitalizing on the ascorbic acid (AA)-mediated chromogenic attenuation mechanism via oxTMB reduction, a colorimetric sensing platform is established by tracking the absorbance variations at 650 nm. This AA quantification strategy achieves superior analytical performance, featuring a detection limit (LOD) of 0.87 μM, a broad linear response spanning 1–40 μM (R 2  = 0.993), and remarkable selectivity against interfering species. Furthermore, this platform is successfully applied to assess total antioxidant capacity in real-world samples, including fresh fruit juices and available beverage. The POD-like catalytic reliability is validated through parallel validation against the established cupric reducing antioxidant capacity (CUPRAC) assay, confirming the robustness of this strategy for practical antioxidant analysis.