Programmable DNA biocomputing circuits for rapid and intelligent screening of SARS-CoV-2 variants.

The frequent emergence of SARS-CoV-2 variants increased viral transmissibility and reduced protection afforded by vaccines. The rapid, multichannel, and intelligent screening of variants is critical to minimizing community transmissions. DNA molecular logic gates have attracted wide attention in recent years due to the powerful information processing capabilities and molecular data biocomputing functions. In this work, some molecular switches (MSs) were connected with each other to implement arbitrary binary functions by emulating the threshold switching of MOS transistors and the decision tree model. Using specific sequences of different SARS-CoV-2 variants as inputs, the MSs net was used to build several molecular biocomputing circuits, including NOT, AND, OR, INHIBIT, XOR, half adder, half subtractor, full adder, and full subtractor. Four fluorophores (FAM, Cy3, ROX, and Cy5) were employed in the logic systems to realize the multichannel monitoring of the logic operation results. The logic response is fast and can be finished with 10 min, which facilitates the rapid wide-population screening for SARS-CoV-2 variants. Importantly, the logic results can be directly observed by the naked eye under a portable UV lamp, thus providing a simple and intelligent method to enable high-frequency point-of-care diagnostics, particularly in low-resource communities.