Improving the Signal-to-Background Ratio during Catalytic Hairpin Assembly through Both-End-Blocked DNAzyme.

ABSTRACT

Catalyzed hairpin assembly (CHA) is an important DNA engineering tool for a variety of applications such as DNA nanotechnology and biosensing. Here we report a hairpin-type of both-end-blocked DNAzyme to improve the signal-to-background ratio during the CHA process. In the design, the DNAzyme activity can be blocked efficiently via locking both ends of the G-rich DNAzyme sequence in the loop and stem (blocking efficiency = 96%) and can be easily recovered during the CHA process (activation efficiency = 94%). The both-end-blocked DNAzyme is by far the most sensitive optical detection mode for monitoring the CHA process that can be used for determination of 0.05 fmol miRNA-21. The fabricated CHA-DNAzyme sensing system was also able to discriminate miRNA-21 from single-/three-base mismatch miRNA-21. The feasibility of real application was also tested via detection of miRNA-21 levels in tumor cell samples. Therefore, the sensing system with the advantages of convenience, high sensitivity, and selectivity is an appealing strategy for miRNA detection.