Roll-to-Roll DNA Nanomachine for Ultrasensitive Electrochemical Determination of miRNA.

MicroRNAs (miRNAs) are a family of endogenous noncoding RNAs with the functions of gene regulation, which serve as promising markers for a range of diseases such as diabetic foot ulcers, cancers, etc. In this work, we engineered a roll-to-roll DNA nanomachine for highly sensitive electrochemical detection of miRNA. A dumbbell-structured DNA probe could be transitioned to be wheel-structured conformation upon target recognition, which rolls around track strands on the surface of gold nanoparticles (AuNPs) in the presence of nicking endonuclease. The resulting single strands on AuNPs are activated for the second round of rolling at the DNA-modified electrode interface, leading to the variation of electrochemical responses. The roll-to-roll amplification behavior allows a wide detection range with a limit of detection as low as 10 aM. The practicability is also demonstrated by the application in human serum samples with satisfactory results. It is expected that the proposed electrochemical method offers a new paradigm to develop miRNA assays based on DNA nanotechnology.