Fig. 4: Proof of concept and evaluation of for SARS-CoV-2.
From: Towards ultra-sensitive and rapid near-source wastewater-based epidemiology
a Setup of the lab-in-a-suitcase platform for two-hour near-source WBE testing. The four stages of the assay and their timelines are shown, including syringe filter sample enrichment (10 min), magnetic beads RNA extraction (40 min), pre-lyophilised one-pot RT-RPA reaction (25 min), and nanodiamond assisted dipstick test with a portable reader readout (45 min). b LoD comparison of two readouts (microscope and reader) based on the model amplicon binding FND strip tests. The microscope readout LoD was 6.4 fM (95% CI: 3.8–11), and the portable reader readout LoD was 17 fM (95% CI: 7.8–36), making the latter 2.6-fold less sensitive in a model system. The dots show means and error bars show the s.d. of repeat measurements (n = 3 technical replicates and n = 3 measurement replicates for each sample). A stretched exponential regressions are shown by solid lines, and shaded areas show the 95% confidence intervals of the fits. c The assay was evaluated on 62 raw wastewater samples, treated via magnetic beads extraction. The wastewater sample RT-qPCR cycle threshold (Ct) was plotted against nanodiamond signals generated both from the microscope readout and from the portable reader. d The receiver operating characteristic curve analysis of the evaluation results on the raw wastewater samples (n = 62). e The sensitivity of the WE-QOSS platform is 95% (95% CI: 83–99) (which compare to the 100% (95% CI: 91–100) based on microscopy readout), and the specificity is 100% (95% CI: 84–100). Green: microscope, Purple: reader. Source data are provided as a Source Data file.
