Electrochemiluminescence (ECL) detection of MicroRNAs using polyethylenimine (PEI)/SiO2 nanoparticles as the indicator

•Using PEI/SiO2 nanoparticles as sensing indicator for ECL detection of miRNAs and PEI as enhancing ECL signal molecules.•The composite nanoparticles has ability to sensitively discriminate ds-DNA from ss-DNA based on their different interactions.•Self-assembled nanoparticles on Nafion/CNT/Ru(bpy)32 + modified electrode surface play the key role for good ECL enhancement.•PEI/SiO2 nanoparticles will further expand the applications of silica composite nanomaterials in the nucleic acid analysis.

There remains a great challenge in the sensitive and selective detection of microRNAs (miRNAs) in cells. In this work, a label-free and enzyme-free assay for ultrasensitive detection of miRNAs using polyethylenimine (PEI)/SiO2 nanoparticles has been developed. The PEI/SiO2 nanoparticles, which serve as an indicator to discriminate availably between single-stranded DNA (ss-DNA) and double helix structure DNA (ds-DNA), are self-assembled on the Nafion/carbon nanotubes (CNT)/Ru(bpy)32 + modified electrode surface by supramolecular effect. What is more, the polymer PEI in the composite nanoparticles has a remarkable enhancing effect on the electrochemiluminescence (ECL) signals of Ru(bpy)32 + immobilized in advance on the Nafion/CNT modified electrode surface by electrostatic interaction. In addition, the enhancement of ECL signals has exactly good linear relationships with the concentration of Let-7a in miRNAs. Finally, this approach paves a way for simple and convenient ECL detection of miRNAs in 116 Colon Cancer Cells with very high sensitivity and good selectivity.