Single-Step Sample-Activated Alternating Sequential Flow Enables Autonomous Multistep Electrochemical Lateral Flow Detection of Mpox Virus DNA

The 2022 multinational mpox virus (MPXV) outbreak and continued cross-border transmission have highlighted limitations of laboratory-confined PCR diagnostics. Here, we report an alternating lateral flow architecture (ALFA) that transforms traditional single-pass lateral flow into a programmable platform for autonomous multistep electrochemical nucleic acid detection following a single prepared-sample introduction. By regulating passive fluid delivery, ALFA enables sequential molecular processing and in situ signal generation without external intervention. Coupled with Ag(I)-mediated mismatch DNA nanocomplexes (MDNs), the system provides electrochemical signal amplification without nucleic acid amplification. ALFA detected MPXV DNA with a limit of detection (LOD) of 1.55 pM and a linear range of 101−105 pM. In urine and saliva spiked with structurally intact viral particles, the lowest statistically distinguishable concentration was 10 copies mL−1. Clinical evaluation of 50 PCR-characterized lesion swab samples yielded 92.11% sensitivity, 100% specificity, and 94.0% accuracy. The platform also maintained stable performance over an estimated 112 days. ALFA therefore provides a programmable lateral flow framework for rapid, amplification-free, decentralized nucleic acid diagnostics.