Fiber-in-Tube Design of a CuFe2O4@Conducting Polymer with Synergistically Enhanced Peroxidase-like Activity for Total Antioxidant Capacity Assays

The exploration of novel nanozymes with a high catalytic efficiency is crucial for their biosensing applications. Intricate hollow nanostructures possess distinct hierarchical open and porous features, usually presenting fascinating physicochemical properties. In this work, we have demonstrated the fabrication of a hierarchical fiber-in-tube CuFe2O4@conducting polypyrrole (PPy) nanostructure for peroxidase mimicking. Owing to the unique confined structure and synergistic effect, an exceptional peroxidase-like performance of CuFe2O4@PPy is achieved compared with the pristine CuFe2O4 nanofibers and PPy nanotubes alone. The prepared catalyst displays a desirable long-term and cycling stability. The experimental results demonstrate the key role of the formation of hydroxyl radicals for peroxidase mimicking. Based on the outstanding peroxidase-like activity, a high-efficiency ascorbic acid (AA) colorimetric sensor is developed, also displaying a satisfactory selectivity. Furthermore, according to the high sensitivity of the CuFe2O4@PPy nanotubes to detect AA, a total antioxidant capacity (TAC) sensor for a series of real samples has been developed. This work provides a new approach to construct efficient nanozymes with high efficiencies and develop a simple TAC assay with further vision in the fields of biosensing and food technology.