A Novel ECL Sensing System for Ultrahigh Sensitivity miRNA-21 Detection Based on Catalytic Hairpin Assembly Cascade Nonmetallic SPR Effect.

A novel electrochemical luminescence (ECL) sensing system is designed based on the catalytic hairpin assembly (CHA) cascade nonmetallic surface plasmon resonance (SPR) effect for ultrasensitive and selective miRNA-21 detection. In the CHA cycles, much more target miRNA-21 is captured to amplify the detection signal and enhance sensitivity. Meanwhile, the specific recognition between streptavidin (SA) and biotin, together with the SPR effect of SnS2 nanoplates on perylene tetracarboxylic acid, further amplifies the ECL signal. Together, miRNA-21 can be quantified with a limit of detection of 0.6 aM in the novel ECL system with ultrahigh sensitivity and selectivity. The ECL biosensor exhibits excellent stability and reproducibility as well as good practicality for miRNA-21 detection in real human serum.