Click Chemistry-Actuated Digital DNA Walker Confined on a Single Particle toward Absolute MicroRNA Quantification

A versatile single magnetic nanoparticle (MNP)-confined, click chemistry-actuated digital DNA walker (ddWalker) machine is devised for the absolute quantification of microRNA (miRNA). This delicate ddWalker allows one target molecule to fix one DNA walking leg on a single MNP, following the Poisson statistics through a specific click chemical DNA ligation, which will initiate single molecule DNA walking to stepwise cleave the molecular beacon tracks strictly constrained on the leg-hold MNP without cross-particle reaction, fluorescently lighting up the exact MNP. Accordingly, the initial miRNA input can be digitally and faithfully reflected by the number of fluorescent-positive MNPs counted by a total internal reflection fluorescent microscope, enabling the absolute and precise miRNA quantification down to the femtomolar level without external calibration. This flexible ddWalker design provides a new digital signaling concept and elegantly expands the toolbox for digital biosensing.

Automated summary

The versatile single magnetic nanoparticle-confined, click chemistry-actuated digital DNA walker machine enables absolute quantification of microRNA, reflecting the initial miRNA input digitally and faithfully by counting fluorescent-positive MNPs without external calibration. This design expands the toolbox for digital biosensing with a new digital signaling concept.