A fully integrated sample-to-answer diagnostic platform enables rapid quantification of post-transplant infection at the point-of-care

Opportunistic infections after organ transplantation require frequent monitoring over years. However, current diagnostic tests are inaccessible to patients in resource-limited settings. Here, we present a microfluidic-enhanced nucleic acid test for on-site reporting (MONITOR), a fully integrated, sample-in-answer-out platform for point-of-care (POC) detection of opportunistic infections. MONITOR employs a gene-specific DNAzyme that, upon integration with recombinase polymerase amplification, enables CRISPR-like trans-cleavage signal amplification with single-molecule sensitivity. It further incorporates a rapid, extraction-free protocol for processing the urine sample, lyophilized assay reagents for cold-chain-free storage and transportation, and a 3D-printed microfluidic cartridge for self-contained, contamination-free fluid handling. A portable real-time fluorescence reader and smartphone application are further developed to enable on-site quantification. Clinical validation showed complete concordance with qPCR across the tested cohorts and a field trial identified high-risk patients with systemic BK polyomavirus infection. MONITOR fulfills ideal criteria for POC testing, offering a practical solution for decentralized, quantitative viral monitoring in low-resource settings. Opportunistic infections are among the leading causes of graft loss for organ transplant recipients. Here authors introduce a protein-free CRISPR-like assay platform called MONITOR, which, when combined with pre-amplification, achieves single-molecule sensitivity, enabling sample-in-answer-out quantification of post-transplant infections in resource-limited settings.