A sensitive Fe3O4@MnO2 nanocatalyst designed for visual determination of total antioxidant capacity in fruit juice

Fruit juice is kind of popular beverage food worldwidely, and its total antioxidant capacity (TAC) is generally considered as an important index for people’s rational diet, thus accurate evaluation of its TAC is essential for human health guidance. Herein, we constructed a sensitive Fe₃O₄@MnO₂ nanocatalyst that was delicately cored with magnetite nanoparticles (Fe₃O₄ NPs) and encapsulated with manganese dioxide (MnO₂) nanoshells for fast and accurate TAC colorimetric analysis in fruit juice. The data showed the fabricated Fe₃O₄@MnO₂ nanocatalysts performed with remarkable oxidase mimetic activities and could catalyze oxidization of colorimetric substrate without additional H₂O₂, and the limit of detection (LOD) was about 0.39 μM for ascorbic acid (AA) evaluation. Applied in commercial fruit juice products, the fabricated Fe₃O₄@MnO₂ nanocatalysts showed a reliable and visual assessment for the accurate TAC analysis. In addition, the fabricated Fe₃O₄@MnO₂ nanocatalysts could be easily recycled due to their intrinsic superparamagnetic property. Together, an intellegent Fe₃O₄@MnO₂ nanocatalyst was well developed for visual TAC analysis in fruit juice with convenient applications in future.