Visualized lateral flow assay for logic determination of co-existing viral RNA fragments

Different types of pathogenic viruses that have common transmission path can be co-infected, inducing distinct disease procession in comparison to that infection of one. Also, in the post COVID-19 time, more types of respiratory infectious virus are becoming prevalent and are concurrent. Those bring an urgent need for detection of co-existing viruses. Here, we propose a visualized lateral flow assay for logic determination of co-existing viral RNA fragments. In the presence of specific viral RNA inputs, DNAzyme is de-blocked according to defined logic, and catalyzes the hydrolysis of hairpin-structural substrate. One of cleaved substrates contains DNAzyme domain to realize dual signal amplification, which obtains copious of the other cleaved substrates. The cleaved substrates act as linking strands for bridging DNA-modified gold nanoparticles onto lateral flow strip to induce coloration on test line. "AND", "OR" and "INHIBIT" controlled lateral flow assays are respectively demonstrated for co-existing viral RNA detection, and the visual results can be obtained by the same kind of prepared strip, without need of re-fabricating strips according to logic systems. The work provides a flexible, convenient, visual and logic-processing strategy for simultaneous analysis of co-existing viruses.