Cu Nanoparticles/CoO/Carbon Nanofibers as an Enhanced Peroxidase Mimic for Total Antioxidant Capacity Assessment in Drinks

With the improvement of the quality of life, the assessment of total antioxidant capacity (TAC) has attracted much attention in the field of a healthy diet, food analysis, or health guidelines. In this work, Cu nanoparticles (NPs)/CoO/carbon nanofibers (CNFs) as a promising nanozyme for peroxidase (POD) mimicking was synthesized by electrospinning and carbonation. Subsequently, a colorimetric sensing platform is constructed for TAC assessment by using 3,3′,5,5′-tetramethylbenzidine (TMB) as a chromogenic substrate based on Cu NPs/CoO/CNFs under presence of H2O2. The enhanced POD catalytic efficiency of Cu NPs/CoO/CNFs for TMB oxidation (ox-TMB) was about 3.2-fold higher than that of bare Cu NPs/CNFs or CoO/NFs, which was ascribed to the synergistic catalytic effect and the generation of heterogeneous interfaces between Cu NPs and CoO in CNFs. When some antioxidants such as AA, FA, TA, and GA were introduced in the chromogenic system, ox-TMB was reduced to colorless TMB, allowing the subsequent assessment of TAC. The results show that the limits of detection toward AA, FA, TA, and GA were 8.7, 8.3, 2.7, and 2.4 μM, respectively. Moreover, this proposed method was used for the TAC assay in real samples including fresh juices and commercial beverages, which showed good promise in practical applications such as food nutrition assessment, food analysis, personalized nutrition intervention, or staple food research.