%0 Journal Article %A Torrente Rodríguez, Rebeca Magnolia %A Campuzano Ruiz, Susana %A Ruiz Valdepeñas Montiel, Víctor %A Montoya Miñano, Juan José %A Pingarrón Carrazón, José Manuel %T Sensitive electrochemical determination of miRNAs based on a sandwich assay onto magnetic microcarriers and hybridization chain reaction amplification %D 2016 %@ 0956-5663 %U https://hdl.handle.net/20.500.14352/96114 %X A novel electrochemical approach for determination of miRNAs involving a sandwich hybridization assay onto streptavidin-magnetic beads (Strep-MBs), hybridization chain reaction (HCR) amplification and amperometric detection at disposable screen-printed carbon electrodes is reported. Using miRNA-21 as the target analyte, a dynamic linear range from 0.2 to 5.0 nM with a 60 pM (1.5 fmol in 25 μL) detection limit was obtained. The achieved sensitivity is 24-fold higher than a non-HCR amplification approach involving conventional sandwich type assay onto MBs. Moreover, the whole assay time lasted 1 h 45 min which is remarkably shorter than other reported methodologies. The methodology exhibited full selectivity against other non-complementary miRNAs as well as an acceptable discrimination between homologous miRNA family members. The applicability of this novel approach was demonstrated by determining mature miRNA-21 in total RNA (RNAt) extracted from tumor cells and human tissues. %~