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 (center dot OH) produced in catalytic process. Since the generated center dot 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 mu M, and low detection limits of 4.0 x 10(-5) M and 4.0 x 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.