Localized DNA catalytic hairpin assembly reaction on DNA origami for tumor-associated microRNA detection and imaging in live cells

Abstract

Dynamic DNA self-assembly (DDSA) has been developed for highly sensitive monitoring intracellular cancer biomarkers via in situ signal amplification. However, each step of reaction depends on the diffusion of DNA strands within the three-dimensional cellular environment, which greatly limits the reaction efficiency. Herein, we proposed a localized catalytic hairpin assembly (CHA) reaction on DNA Origami with the purpose of detection and imaging of intracellular microRNA-21. In this strategy, 8 pairs of DNA hairpins of CHA reaction alternately hybridized to the protruding single strands of DNA origami rectangle, so that the whole reaction process is constrained in a compact space and independent on the diffusion of the DNA strands. Obviously, this localized CHA reaction offered faster reaction kinetics. Our results confirmed that, compared to the traditional CHA reaction, constraining DNA hairpins onto a rectangular DNA origami increased the reaction rate and the sensitivity. In addition, DNA origami rectangle could also play as a carrier to deliver DNA hairpins to the cytoplasm and protect DNA hairpins from the attack of nuclease. This strategy provided a versatile platform which could be easily integrated with reported DDSA-based strategy and therefore showing a wide application prospect.