Rapid and Sensitive Electrochemical Detection of MicroRNA by Gold Nanoparticle-catalyzed Silver Enhancement

MicroRNAs(miRNAs) have played the vital role in the regulation of gene expression and have been considered as potential biomarker candidates for early cancer diagnosis. Rapid and sensitive detection of microRNAs is highly desired. Here we present a rapid and sensitive method to determine microRNAs based on the technology of gold nanoparticles catalyzed silver staining enhancement. The new method involves the sandwich hybridization of a capture probe immobilized on magnetic bead, a reporter probe assembled on gold nanoparticle and a miRNA target, catalytic silver precipitation by gold nanoparticles, magnetic collection of the enhanced sandwich complex, dissolution of the silver precipitation and stripping detection. The proposed method successfully fulfilled the microRNA-7a assay in less than 70 min and the detection limit was as low as 15 fM.The proposed biosensor may hold great promise in biological monitoring of microRNA.