Target-Triggered Polymerization of Branched DNA Enables Enzyme-free and Fast Discrimination of Single-Base Changes.

Single-base changes lead to important biological and biomedical implications; however, the discrimination of single-base changes from normal DNA always remains a grand challenge. Herein we developed a DNA recognition and amplification system based on artificial branched DNA, namely, target-triggered polymerization (TTP), to realize enzyme-free and fast discrimination of single-base changes. Branched DNA as monomers rapidly polymerized into DNA nanospheres only with the trigger of specific DNA. Our TTP system worked reliably over a wide range of conditions. Remarkably, our TTP system was capable of discriminating base-changing DNA from normal DNA, including distinguishing 1-4 nucleotide changes and positions of single base, which was attributed to the significant amplification of small differences in hybridization thermodynamics and kinetics. We further proposed a theoretical method for calculating the hybridization probability of nucleic acids, which performed highly consistent with experimental results.