Abstract
Detection of microRNAs (miRNAs) by using precise and convenient biosensing methods is desired in biochemical study and early clinical diagnosis. We constructed an innovative programmed all-DNA biosensing platform by using homogeneous 3D DNA nanospheres as signaling reporter and entropy-driven enzyme-free amplification strategy to detect miRNA-141. The self-assembly 3D DNA nanosphere was obtained by the highly ordered aggregation of two kinds of single strand of DNA (ssDNA) labeled with 6-carboxyfluorescein (FAM) and two kinds of linker DNA strands in terms of Watson-Crick base pairing rule. The highly ordered aggregation of the ssDNA resulted in an enhancement of fluorescence signal by 69 % compared to that of monodisperse one, which significantly improved the sensitivity of the biosensor. Target microRNA triggered the release of bulk BHQ1-DNA from the quencher complex, leading to the fluorescence quenching of the DNA nanosphere. The present biosensing platform achieves a detection limit of 0.2 nM with a linear range from 0.4 nM to 4.0 nM. The results based on human serum samples indicate that the developed DNA biosensing platform could be potentially applied to early clinical diagnosis.
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