A Novel Label-Free Fluorescence Strategy Based on Dumbbell Probe for Sensitive Detection of DNA Ligase

Abstract

Based on the principle that DNA ligation reaction mediates hydrolysis of the dumbbell probe (DP), a novel label-free strategy for sensitive detection of DNA ligase was developed. DNA ligase ligated the nick on DP to generate a fully closed dumbbell DNA structure, which could prevent the hydrolysis of exonuclease, after combining with SYBR Green I (SG I), a strong fluorescent signal was obtained. In the absence of DNA ligase, DP was hydrolyzed into single nucleotides by exonuclease, resulting in a rather weak signal. The linear range of this method for detecting T4 DNA ligase is 0.00004 - 0.004 U/μL, and the detection limit is 0.00003 U/μL. The proposed strategy is sensitive, inexpensive and easy to operate, which may offer an effective tool for further applications in new drug screening.