An enzyme-free probe based on G-triplex assisted by silver nanocluster pairs for sensitive detection of microRNA-21


A sensitive ratiometric fluorescence probe based on hybridization chain reaction (HCR) was constructed for sensitive detection of miRNA-21 by using G-triplex and silver nanocluster pairs (AgNC pairs) as an enzyme-free and label-free signal output group. miRNA-21 was used as the primer for the hybridization chain reaction of molecular beacon 1 (MB1) containing the locked G-triplex sequence and molecular beacon 2 (MB2) with intact AgNC pairs at the 5′ and 3′ end activation. The double-stranded product was obtained along with the opening of the G-triplex and the separation of the AgNC pairs. A detection limit of 67 pM and a linear detection range of 0.1–300 nM were obtained for miRNA-21 determination. The proposed strategy enabled the monitoring of miRNA-21 levels in at least three cell lines, indicating that it provided new ideas for detecting miRNA in real samples.

Graphical abstract

MB1 and MB2 contained the locked G-triplex sequence and silver nanocluster pairs (AgNC pairs), respectively. In the presence of target, the hybridization chain reaction (HCR) between MB1 and MB2 was initiated. At the same time, the locked G-triplex was released and combined to the dye thioflavin T (THT) to increase fluorescence, while the separation of the AgNC pairs caused the fluorescence to decrease. The double-stranded (ds) DNA product was generated to form a ratiometric signal to be detected.

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This work was supported by the National Natural Science Foundation of China (No. 21775132), the Natural Science Foundation of Hunan Province (No.2018JJ2388), Hunan 2011 Collaborative Innovation Center of Chemical Engineering & Technology with Environmental Benignity and Effective Resource Utilization, the project of innovation team of the Ministry of Education (IRT_17R90), and “1515” academic leader team program of Hunan Agricultural University.

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Correspondence to Chunyan Chen or Changqun Cai.

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Zhao, X., Wang, S., Zou, R. et al. An enzyme-free probe based on G-triplex assisted by silver nanocluster pairs for sensitive detection of microRNA-21. Microchim Acta 188, 55 (2021).

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  • MicroRNA-21; G-triplex
  • Enzyme-free probe
  • Label-free probe
  • Silver nanocluster pairs