From Mn-Triazine Crystalline Framework to MnOx@NC: Biomimetic Double-Enzyme Activity and Labeling of Ascorbic Acid as Well as Application in Pharmaceuticals

Abstract

Imbalance in the levels of ascorbic acid (AA) can pose a risk to human health. Therefore, it's essential to establish an accurate method for the detection of AA. In this work, a novel N-doped carbon composite (MnO_x@NC) with dual enzyme-like activities to detect AA was prepared by calcination of Mn-MOF containing H₃TTPCA ligand. Interestingly, the •O₂⁻ that leads to its oxidase-like activity was not formed by dissolved oxygen, but came from the synergistic effect of lattice oxygen generated by calcination and the transformation of Mn^II/Mn^III/Mn^IV, and the presence of H₂O₂ provided much •OH, which caused its peroxidase-like activity. Meanwhile, the residual N element came from H₃TTPCA ligand assisted the catalytic process. Accordingly, a dual-signal sensing platform and smartphone-assisted recognition for detection of AA was developed and a colorimetric sensor array was established to distinguish three antioxidants. This work also demonstrates considerable promise for the detection of AA in authentic pharmaceuticals.