Scheme 1

Proposed e-miRchip platform for miRNA analysis. a The e-miRchip was fabricated with photolithography with the deposition and etching of the conductive gold and insulating parylene layers on glass to make the designed microaperture array. Electrodeposition of gold was performed to fabricate GNEs in the microaperture (i), and the GNEs were functionalized with SLP immobilization and 6-mercapto-1-hexanol (MCH) backfilling (ii). The miR-21 was captured by the SLPs (iii) and the signals were amplified with the AgNRs (iv). b Direct, ultrasensitive detection of miR-21 expression in lung cancer. The expression of miR-21 from the lung cancer cells is examined by direct electrochemical measurement on the e-miRchip