A paper-microfluidic platform for viral RNA and protein detection in saliva for SARS-CoV-2 diagnosis

Rapid and sensitive diagnostic methods for infectious diseases are critical for public health management. The reliance of immunoassays on humoral immune responses results in lower detection rates during early infection compared to nucleic acid tests. To address this limitation, we presented a paper-microfluidic platform for rapid and low-cost SARS-CoV-2 diagnosis that simultaneously detected viral RNA and proteins in saliva. The system integrated a streamlined saliva processing protocol, a paper-based colorimetric reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay for viral RNA detection (LOD: 10 copies/μL; Dynamic range: 10–10 7 copies/μL), and a paper-based ELISA (p-ELISA) assay for immunoglobulin titer quantification (LOD: 0.5 ng/μL; Dynamic range: 0.5–60 ng/μL). Lyophilized reagents ensured operational simplicity and long-term stability, while results were interpreted visually or via smartphone imaging. The entire assay was completed within 60 min, with recoveries of 93 %–106 % in saliva samples. By facilitating non-invasive saliva analysis and concurrent assessment of viral load and antibody titers, this platform will provide a comprehensive diagnostic solution, particularly valuable in resource-limited settings. • Paper-microfluidic device enabled sensitive nucleic acid detection within 40 min. • Paper-based immunoassay required less sample and provided faster results. • Saliva-based platform integrated infection monitoring and immunity evaluation. • Generic platform for multiplexed infectious disease diagnostics.