Hierarchical manganese dioxide nanoflowers enable accurate ratiometric fluorescence enzyme-linked immunosorbent assay

Abstract

We first developed a green, mild and rapid method for the preparation of hierarchical manganese dioxide nanoflowers (MnO₂ NFs) as nanozymes with intrinsic oxidase-like activity using citric acid for the reduction of potassium permanganate. The open structure of MnO₂ NFs can lead to a larger specific surface area for improving the antibody loading amount and oxidase mimicking activity. In addition, carboxyl groups from the residual citric acid on the surface of MnO₂ NFs afford a good affinity with the antibody through an amidation coupling reaction, which does not need complex surface modification anymore. Then, a reliable ratiometric fluorescence nanozyme-linked immunosorbent assay towards C-reactive protein (CRP) was designed successfully based on the MnO₂ NFs. The high sensitivity and clinical feasibility of the presented methodology were demonstrated, which hold great promise in biomedical fields. Moreover, the mild and simple process for the synthesis of MnO₂ NFs will make good contributions to many other applications.