Impedimetric detection of miRNA-34a using graphene oxide modified chemically activated graphite electrodes

Graphene oxide (GO) modified graphite electrodes were developed for sensitive and selective impedimetric detection of miRNA-34a which is the biomarker of Alzheimer's disease and various types of cancer. For this purpose, pencil graphite electrodes (PGEs) were used as recognition platform. First, chemical activation of the surfaces of PGEs was done using covalent agents (CA), then GO modification was performed at the surface of chemically activated disposable PGEs. The results of microscopic and electrochemical characterization of GO-CA-PGEs were represented. The step-by-step hybridization process was implemented for impedimetric detection of miRNA-34a and the experimental conditions were optimized for each modification/immobilization step. Under the optimum conditions, the detection limits for miRNA-34a target were estimated as 1.84 mu g/mL (261.7 nM) in PBS (pH 7.4) and 0.5 mu g/mL (72.5 nM) in diluted FBS:PBS (1:1). The selectivity of GO based impedimetric biosensor was tested against to other miRNAs; miRNA-15a, miRNA-155 and miRNA-660. (C) 2018 Elsevier B.V. All rights reserved.