A Facile Label-Free Colorimetric Assay for DNase I Activity Based on the Peroxidase-Like Activity of Functional Nucleic Acids.

DNase I plays a crucial role in fundamental biological processes, including gene expression, DNA repair, and apoptosis. Therefore, it is important to develop a simple and efficient method to detect DNase I activity. In this work, a colorimetric assay based on functional nucleic acid for sensitive DNase I detection was reported. The functional nucleic acids with G-rich bases exhibit peroxidase-like activity under acetic acid conditions, capable of catalyzing the oxidation of chromogenic substrate 3,3',5,5'-tetramethylbenzidine (TMB). The specific nucleic acid is designed as the substrate for DNase I, which can hydrolyze the strand and reduce the catalytic activity of the reaction system. Based on this, a sensitive, simple, efficient, and cost-effective colorimetric detection platform was constructed for the quantitative analysis of DNase I. The detection limit (3σ/s) for DNase I was 0.046 U/mL with a linear range of 0.1-1 U/mL. Moreover, the practicality of this colorimetric detection platform was demonstrated by detecting DNase I in human serum.