Os(VI)bipy-based electrochemical assay for detection of specific microRNAs as potential cancer biomarkers

Recently, altered expression levels of microRNAs (miRNAs) - short noncoding RNA molecules which bind to mRNAs and thus regulate gene expression - were observed in many cancer cells. miRNA expression profiling is therefore of great interest, but current standard methods are still considered relatively laborious and expensive. Electrochemistry has a potential to become quick and inexpensive alternative. Here, we describe modification of miRNA with an electroactive complex composed of six-valent osmium and 2,2'-bipyridine, Os(VI)bipy, specifically binding to the 3'-end of the ribose, which is detectable at hanging mercury drop electrode at femtomole level due to an electrocatalytic nature of a resulting signal. By combining miRNA labeling step with magnetic beads-based hybridization assay, detection of specific miRNA sequence from a mixture of other noncomplementary miRNAs was possible. (c) 2013 Elsevier B.V. All rights reserved.