Novel electrochemical biosensing platform for microRNA: Bivalent recognition-induced nanoparticle amplification occurred in nanochannels

MicroRNAs are novel and reliable biomarkers for early cancer diagnosing. However, accurate detection of the ultralow amount of a specific microRNA remains a big challenge. Herein, an electrochemical biosensing platform based on bivalent recognition-induced nanoparticle blocking in nanochannels for signal amplification is developed. Bivalent recognition is realized by two oligonucleotides, individually containing the complementary sequence for opposite ends of the target microRNA. One oligonucleotide is anchored into the alumina nanochannels and the other is bonded onto the SiO 2 nanoparticles. The presence of the target microRNA increases the blockage effect of the nanochannels and which is greatly amplified by bringing the nanoparticles into the nanochannels. Methylene blue (MB) is chosen as the reporter of the blockage effect. The amount of MB fluxing through the nanochannels is monitored at a working electrode functionalized with MoS 2 nanoplates and treated by the electrochemical method to further amplifying the signal. The reductive current of MB is quantitatively dependent on the concentration of microRNA. Using microRNA-21 as the model target, the electrochemical signal exhibited a linear dependence on the concentration of the target in a wide range of 100 aM to 1 nM. The platform could be readily extended to other nucleic acids.