Multiplex monitoring of Alzheimer associated miRNAs based on the modular logic circuit operation and doping of catalytic hairpin assembly

In recent years, DNA logic gates have been extensively applied in developing multiplex processing platforms to provide an accurate decision on the diagnosis of multi-factor diseases. In this work, we presented a new cascaded logical operator by combining different modules for computational monitoring of four miRNAs related to Alzheimer disease (has-miR-143-3p, has-miR-18b-5p, has-miR-424-5p, and has-miR-93-5p). Herein, three sequential logic gates were programed that upon entering the miRNA inputs, delivered the trigger strand of CHA (catalytic hairpin assembly) reaction through a cyclic amplification. Afterward, the product of the CHA reaction, three-way junction, could induce the gold nanoparticles aggregation. This phenomenon led to generate a blue color of the solution that enabled visualizing and quantitative measurement of the assay. The output signals were recorded through reading the absorbance intensity transition, dynamic light scattering (DLS), and transmission electron microscopy (TEM). Taken together, the proposed assay by taking advantage of excellent generality, naked eye observation, the 4-plex detection, simplicity, enzyme-free nature, and two-steps process without any immobilization and washing has addressed the limitation of the previous systems. Moreover, the amplified monitoring of low-abundant of target miRNAs was accomplished with a limit of detection as low as 5 pM.