Ultra-fast, palm-sized platform for visual point-of-care virus detection using convective PCR with gold nanoparticle probes.

Convective PCR (cPCR) offers rapid and efficient DNA amplification in as little as 10 min, presenting a promising alternative to traditional PCR. However, current palm-sized cPCR devices fail to achieve one-pot visual detection, limiting their utility for point-of-care testing. Here, we present a visual convective PCR (Vis-cPCR) assay that integrates reverse transcription, ultra-fast cPCR, nested invasive reactions, and gold nanoparticle probes (AuNPs)-based colorimetric detection into a single-tube, one-pot system. This assay eliminates the need for time-consuming nucleic acid extraction and purification by employing a room-temperature chemical lysis step, which rapidly releases viral RNA from pharyngeal swabs in just 2 min and is fully compatible with downstream detection. The palm-sized cPCR device enables the entire process-including reverse transcription, DNA amplification, amplicon identification, and visual signal generation-to be completed in approximately 30 min. The Vis-cPCR assay demonstrates high sensitivity (as low as 10 copies) and specificity for detecting a panel of viruses, including SARS-CoV-2, influenza A/B, western equine encephalitis virus, tick-borne encephalitis virus, chikungunya virus, and Zika virus. Validation using 30 clinical pharyngeal swab samples and 42 artificially prepared arboviral RNA samples showed 100% agreement with RT-qPCR results. By combining rapid sample preparation, ultra-fast amplification, and visual detection, Vis-cPCR represents a significant advancement in point-of-care diagnostics, offering a simple, cost-effective, and highly efficient tool for on-site pathogen screening in resource-limited settings and emergency situations.