Sensing multiplex microRNAs using dual-functional fork-type-track DNA nanomachine on optical fiber

Abstract

We propose a simple and robust biosensing platform which can be used for accurate determination of multiplex microRNA targets in biological samples. We develop the sensor by immobilizing a novel DNA nanomachine system on the surface of a gold-nanoparticles-modified optical fiber, which contains a uniquely designed dual-functional fork-type track chain with a FAM-labeled DNAzyme recognition site on one branch and a rolling-loop-amplification (RCA) primer on the other. The strategy allows two amplification strategies, i.e., DNA walking and RCA, to be easily achieved as the target microRNAs are in the sample to initiate the corresponding reactions. Two different microRNAs (miRNA-21 and miRNA-375 in the study) are independently and accurately determined without interference from each other, by respectively measuring fluorescence and chemiluminescence signals generated from DNA walking and RCA. The results show that the method is capable for multiplex micorRNA assays with high sensitivity (limit-of-detection 0.21 pM for miRNA-21 and 0.018 pM for miRNA-375) and high selectivity, and the sensor exhibits good repeatability and storage stability. The method successfully determines microRNAs in MCF-7, Hela and MCF-10A cells, showing its ability to analyze real complex biological samples.