▎ 摘　　要

The present study describes the construction of a sensitive electrochemical genosensor for detection of miR-200a using ferrocene-functionalized graphene oxide nanosheets (Fc-GO) as an electroactive label. For this purpose, a glassy carbon electrode (GCE) was modified by amino-functionalized CuO nanoparticles decorated on MnO2 nanorods (NH2-CuONPs-MnO2NRs). The process of the genosensor construction is confirmed by electrochemical impedance spectroscopy (EIS). A sensing mechanism has been proposed based on the pi-stacking interaction between Fc-GO nanosheets and the aromatic bases of DNA. The basis of the assay is based on the interaction of the electroactive label of Fc-GO nanosheets with ss-DNA in the absence of the target and its release after hy-bridization of the ss-DNA with the target, followed by a severe decrease in the current response. Using the genosensor, miR-200a can be measured in the concentration range of 1.0 fM to 0.1 mu M and with a detection limit of 0.29 fM using the differential pulse voltammetry method. Depending on the response of the genosensor, a single-base mismatch as well as a non-complementary-one can be detected from the target sequence. Further-more, the genosensor is capable of measuring miR-200a in a real sample.