Simple and Regulable DNA Dimer Nanodevice to Arrange Cascade Enzymes for Sensitive Electrochemical Biosensing

Herein, a simple and regulable DNA dimer nanodevice was obtained by the assembly of two hairpin DNA monomers of H1 and H2 to control the distance between model enzymes horseradish peroxidase (HRP) and glucose oxidase (GOx) for sensitive electrochemical detection of microRNA. In detail, auto-terminated DNA polymerization reaction was designed on H1 and H2 monomers that decorated with HRP and GOx, respectively, to produce two half-released DNA monomers, which were spontaneously hybridized to each other, thereby obtaining a DNA dimer nanodevice with a rigid dsDNA linker between two DNA monomers. By varying the length of the dsDNA linker on the DNA dimer nanodevice, the distance between GOx and HRP had been regulated to the optimum and the most efficient enzyme cascade reaction was acquired for constructing a sensitive electrochemical microRNA-21 biosensor with a detection limit of 0.03 pM. In summary, the proposed DNA dimer nanodevice avoided the disadvantages of poor biocompatibility and controllability originated from traditional scleroid scaffolds and showed obvious advantages in terms of better assembly yield than previous complicated DNA scaffolds, which provided a novel strategy for developing a high-efficiency enzyme cascade catalytic system and showed great potential in other clinical diagnosis and bioanalysis application.