title: Label-free detection of microRNA: two-step signal enhancement with a hairpin-probe-based graphene fluorescence switch and isothermal amplification.
abstract: A label-free approach with multiple enhancement of the signal for microRNA detection has been introduced. The key idea of this strategy is achieved by taking advantage of a novel graphene oxide (GO)/intercalating dye based fluorescent hairpin probe (HP) and an isothermal polymerization reaction. In this paper, we used microRNA-21 (mir-21) as the target to examine the desirable properties of this assay. When the target, as a "trigger", was hybridized with the HP and caused a conformation change, an efficient isothermal polymerization reaction was activated to achieve the first step of the "signal" amplification. After incubation with the platform of GO/intercalating dye, the formed complex of DNA interacted with the high-affinity dye and then detached from the surface of the GO, a process that was accompanied by distinguishable fluorescence recovery. Further signal enhancement has been accomplished by a mass of intercalating dye inserting into the minor groove of the long duplex replication product. Due to the efficient and multiple amplification steps, this approach exerted a substantial enhancement in sensitivity and could be used for rapid and selective detection of Mir-21 at attomole levels. Proof-of-concept evidence has been provided for the proposed cost-effective strategy; thus, this strategy could expand the application of GO-material-based bioanalysis for nucleic acid studies.
authors: MOE Key Laboratory of Laser Life Science & Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou 530631, PR China.
authors: Xiao
authors: X
authors: Zhu
authors: Xiaoming
authors: X
authors: Zhou
authors: Da
authors: D
authors: Xing
mesh_terms: D001483:Base Sequence; D004396:Coloring Agents; D004247:DNA; D005453:Fluorescence; D005456:Fluorescent Dyes / Q000737:chemistry*; D006108:Graphite; D007364:Intercalating Agents; D035683:MicroRNAs / Q000032:analysis*; D009693:Nucleic Acid Hybridization; D009696:Nucleic Acids; D010087:Oxides
chemical_list: D004396:Coloring Agents; D005456:Fluorescent Dyes; D007364:Intercalating Agents; D035683:MicroRNAs; D009696:Nucleic Acids; D010087:Oxides; D006108:Graphite; D004247:DNA