A General Signal Amplifier of Self-Assembled DNA Micelles for Sensitive Quantification of Biomarkers.

Owing to the excellent structural rigidity and programmable reaction sites, DNA nanostructures are more and more widely used, but they are limited by high cost, strict sequence requirements, and time-consuming preparation. Herein, a general signal amplifier based on a micelle-supported entropy-driven circuit (MEDC) was designed and prepared for sensitive quantification of biomarkers. By modifying a hydrophobic cholesterol molecule onto a hydrophilic DNA strand, the amphiphilic DNA strand was first prepared and then self-assembled into DNA micelles (DMs) driven by hydrophobic effects. The as-developed DM showed unique advantages of sequence-independence, easy preparation, and low cost. Subsequently, amplifier units DMF and DMTD were successfully fabricated by connecting fuel strands and three-strand duplexes (TDs) to DMs, respectively. Finally, the MEDC was triggered by microRNA-155 (miR-155), which herein acted as a model analyte, resulting in dynamic self-assembly of poly-DNA micelles (PDMs) and causing the recovery of cyanine 3 (Cy3) fluorescence as the DMTD dissociated. Benefiting from the "diffusion effect", the MEDC herein had a nearly 2.9-fold increase in sensitivity and a nearly 97-fold reduction in detection limit compared to conventional EDC. This amplifier exhibited excellent sensitivity of microRNAs, such as miR-155 detection in a dynamic range from 0.05 to 4 nM with a detection limit of 3.1 pM, and demonstrated outstanding selectivity with the distinguishing ability of a single-base mismatched sequence of microRNAs. Overall, the proposed strategy demonstrated that this sequence-independent DNA nanostructure improved the performance of traditional DNA probes and provided a versatile method for the development of DNA nanotechnology in biosensing.