Ruthenium-based metal organic framework (Ru-MOF)-derived novel Faraday-cage electrochemiluminescence biosensor for ultrasensitive detection of miRNA-141

A novel Faraday-cage electrochemiluminescence (ECL) biosensor for the sensitive detection of miRNA-141 was constructed. The capture unit was prepared by immobilizing the capture DNA (cDNA) on the functionalized magnetic nanospheres nanoFe(3)O(4)@SiO2@Au, while the signal unit was ruthenium-based metal organic framework Ru-MOF labeled by signal DNA (sDNA). The recognition scaffold was as follows: the capture unit was immobilized onto the magnetic electrode surface; the target miRNA-141 was caught; the signal unit was further hybridized; the Faraday-cage biosensor structure was formed finally. In this case, the signal unit became part of the electrode surface, the outer Helmholtz plane (OHP) of the proposed electrode was extended, all electrochemiluminophores in the signal unit could take part in the electrode reaction, and thus then the detection sensitivity was greatly improved. Taking advantage of the proposed Faraday-cage cascade, the ECL intensity was found to increase with the logarithm of miRNA-141 concentration. The linear range was wide from 1 fM to 10 pM with a limit of detection 0.3 fM. The selectivity, stability, reproducibility, precision and application of this biosensor were validated. This proposed Faraday-cage ECL biosensor has a potential prospect for clinical miRNA detection. (c) 2018 Elsevier B.V. All rights reserved.