MoS₂-loaded G-quadruplex molecular beacon probes for versatile detection of MicroRNA through hybridization chain...

A molecular beacons (MBs) loaded on molybdenum disulfide (MoS₂) nanosheets as fluorescence probes for sensitive and versatile detection of microRNAs (miRNAs) through hybridization chain reaction (HCR) has been designed. MoS₂ was used as a adsorbent to capture the MBs and a selective fluorescence quencher to reduce the background signal. In the absence of miRNAs, HCR could not be triggered due to the stability of MB probes. The probes attached to the MoS₂ surface, efficiently quenching fluorescence of the G-quadruplex/Thioflavin T. However, the presence of target miRNAs triggers the HCR process to generate large amount of HCR products. Meanwhile, the HCR products of long nanowires chain with abundant G-quadruplexes could not be adsorbed on the surface of MoS₂, and therefore detach from the MoS₂. Consequently, Thioflavin T could be embedded in G-quadruplexes and produced strong fluorescence signal. This fluorescence emission signal could achieve detection of miRNA as low as 4.2 pM and a wide linear ranges from 0.1 to 100 nM. In addition, a versatile fluorescence probe has been developed for detection of miRNA-21 by changing the miRNA-recognition domain of MB. Thus, the fluorescent probe would be a potential alternative tool for biomedical research and clinical molecular diagnostics.