Target-Activated, Light-Actuated Three-Dimensional DNA Walker Nanomachine for Amplified miRNA Detection.

Accurate analysis of microRNA (miRNA) is promising for elucidation of cancer processes and therapeutic effects. In this study, we reported a new target-activated, light-actuated three-dimensional (3D) DNA walker on gold nanoparticles for sensitive detection of miRNA using pyrene-incorporated DNAzyme analogues. In this design, the target miRNA activated the 3D DNA walker system to releases the walking arm. Then, under ultraviolet light irradiation, the pyrene DNAzyme on the walking arm would consecutively cleave the disulfide bonds of substrate strands and recover the fluorescence signal, thus achieving the amplified miRNA detection. The sophisticated design of the light-actuated 3D DNA walker was systematically investigated. Furthermore, this strategy could also be employed for miRNA analysis in serum samples with satisfactory reproducibility. Notably, the proposed light-actuated 3D DNA walker-based technique eliminated the need of enzymes, cofactors, and RNA backbones, thereby significantly improving the stability and efficiency. Overall, the light-actuated 3D DNA walker-based strategy enabled facile, sensitive, and specific detection of miRNA and provided new perspectives in diagnostics.