Vertical growth of rhenium disulfide on rGO empowers multi-signal amplification for ultrasensitive MiRNA-21 detection

Unique rhenium disulfide/reduced graphene oxide (ReS₂/rGO) nanoframeworks were synthesized with a hierarchical layered and porous structure for the ultrasensitive electrochemical detection of microRNA-21 (miRNA-21) by empowering multi-signal amplification strategy of catalytic hairpin self-assembly-hybridization chain reaction (CHA-HCR). The layered and porous nanostructures endowed ReS₂/rGO with a larger specific surface area and more active sites through connecting vertical ReS₂ with rGO which was preferable for promoting the electron transfer over electrode surface because of a conductive network. This nanoframework facilitated the loading of adequate gold nanoparticles to fix the capture probe via Au–S bond. In the presence of the target miRNA-21, the CHA-HCR double amplification reaction could be triggered to generate a long double strand with methylene blue (MB) embedded inside. The electrochemical sensing platform was thus empowered by the unique ReS₂/rGO nanoframeworks to detect miRNA-21 in the range 1 fM ~ 100 pM with the remarkably enhanced sensitivity through detecting the significantly amplified signal from the REDOX reaction of MB inside the long chain. The verification of the miRNA-21 detection in real blood samples further proved the great potential of this new method with the limit of detection reduced down to 0.057 fM and opens a new window for ReS₂ in developing sensitive biosensors for early clinical cancer diagnosis.

Graphical Abstract