A new homogeneous electrochemical sensing system was developed for sensitive detection of microRNA-21 (miRNA-21) based on target-induced glucose release from propylamine-functionalized mesoporous silica nanoparticle (MSN) with glucometer readout. Glucose molecules (as the signal tracers) were initially gated into the pores through the interaction of the negatively charged anchor DNA with the aminated MSN. Upon addition of target miRNA, the analyte competitively hybridized with anchor DNA to form the RNA-DNA duplex, thus resulting in detachment of anchor DNA from the MSN accompanying the pore opening. The loaded glucose molecules released out from the pores because of concentration gradients, which could be detected by using a portable personal glucometer (PGM). Experimental results indicated that the PGM signal increased with the increasing miRNA level, and exhibited a good linear dependence on the miRNA-21 concentration from 50 pM to 5.0 nM with a detection limit of 19 pM under optimum conditions. Additionally, multifunctional mesoporous silica nanoparticles also showed good stability and favorable selectivity, and satisfactory accuracy for the miRNA detection in cell lysates with quantitative real-time polymerase chain reaction (qRT-PCR). Such good analytical performance endows it as a promising scheme for the efficient and convenient detection of miRNA in clinical diagnosis and therapy. Graphical abstract An electrochemical sensing system is designed for detection of microRNA-21 based on target-induced glucose release from propylamine-functionalized mesoporous silica nanoparticle with glucometer readout.
Keywords: Competitive displacement reaction; Electrochemical assay; MicroRNA-21; Multifunctional mesoporous silica nanoparticles; Personal glucometer.