Label-free colorimetric detection of deoxyribonuclease i activity based on the DNA-enhanced peroxidase-like activity of MIL-53(Fe)

In this study, the effect of single-stranded DNA (ssDNA) on the intrinsic peroxidase-like activity of MIL-53(Fe) was investigated. The employment of long ssDNAs could effectively accelerate the H₂O₂-mediated 3,3′,5,5′-tetramethylbenzidine (TMB) oxidation reaction catalyzed by MIL-53(Fe). The high catalytic activity of DNA-modified MIL-53(Fe) was attributed to the strong binding interaction between MIL-53(Fe) and long ssDNAs, resulting in their strong adsorption ability to the substrate TMB. By adjusting the activity of MIL-53(Fe) with ssDNAs of different lengths, a label-free colorimetric method has been developed for the detection of deoxyribonuclease I (DNase I) activity. Importantly, the proposed sensing platform could be generalized to assay other nuclease activities by simply redesigning the nucleic acids paired with the target enzymes. This work shows the high potential of MOF-based enzyme mimics in the assay of versatile biomacromolecules in clinical diagnosis under the introduction of DNA.