Label-free fluorescence detection of hydrogen peroxide and glucose based on the Ni-MOF nanozyme-induced self-ligand emission.

A bifunctional Ni-MOF nanosheet was synthesized and developed for label-free fluorescent detection of H2O2 and glucose. The Ni-MOF exhibited intrinsic peroxidase-like activity and its catalytic activity was demonstrated to be originated from the hydroxyl radicals (•OH) produced in catalytic process. Since the generated •OH enabled terephthalic acid, the non-fluorescent organic ligand of Ni-MOF, to form a strongly fluorescent 2-hydroxy terephthalic acid, the Ni-MOF nanozyme was endowed with dual-function properties of mimicking peroxidase and emitting fluorescence. Based on this bifunctional Ni-MOF nanozyme, the proposed label-free fluorescence sensing strategy was applied to detecting H2O2 and glucose with wide linear ranges of 0.1-20 mM and 8-30 μM, and low detection limits of 4.0 × 10-5 M and 4.0 × 10-6 M, respectively. Furthermore, the bifunctional Ni-MOF-based label-free sensing platform was successfully used for the glucose detection in human serum samples, showing good reproducibility and high accuracy. This strategy provides a green and sensitive method for the determination of small biomolecules in practical applications by the combination of enzyme cascade reaction.