Rapid Colorimetric Determination of microRNA (miRNA) Using an Autocatalytic Entropy-Driven Circuit (AEDC)

Abstract

A colorimetric and rapid signal amplified microRNA (miRNA) detection system based on autocatalytic entropy-driven circuit (AEDC) is reported. The target miRNA-21 (miR-21) was firstly hybridized with the sticky end of the triple-stranded hybrid complex (S, which consisting of a reporter strand (P), a byproduct strand (R) and an assistant strand (Q)), and P strand, which contained the G-quadruplex sequence that was released through the toehold-mediated strand displacement reaction. The G-quadruplex sequence interacted with hemin to form the peroxidase-mimicking DNAzymes and catalyzed the H2O2-mediated oxidation of colorless 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS2−) to the green ABTS•−. Meanwhile, fuel strand (F) hybridized with S to release the target miR-21 and the waste duplex DNA product F-Q was formed, which brings the two split mimic target DNA sequences into proximity to form the intact mimic target DNA sequence (analogue of miR-21). The obtained mimic target DNA as well as the released miR-21 can be cyclically used to trigger autocatalytic EDC reaction, leading to the rapidly enhanced formation of mimic target DNA with the concomitant generation of a higher colorimetric signal. Finally, a colorimetric and rapid miR-21 system based on the hairpin-free AEDC reaction was successfully fabricated. This system also has been applied for the miRNA determination in serum, exhibiting the potential application in the clinical diagnosis.