Aim: Processing of the samples in molecular diagnostics is complex and labor-intensive. An integrated and automated platform for sample preparation and nucleic acid-based detection can significantly relieve this burden for the users. Results: We present a prototype of a versatile and integrated platform for the detection of pathogens in various liquid media. We describe a proof-of-concept for the integrated isolation of bacteria, cell lysis with optional DNA extraction, DNA amplification and detection in two different reactions, loop-mediated isothermal amplification and PCR, on a single microfluidic platform. Conclusion: The platform enables the transition from large sample volume to microfluidic format. The design and open interface enable its versatile application for various nucleic acid-based assays, from simple to complex setups. Lay abstract DNA-based detection of the pathogens in liquid samples demands many complex steps, various pieces of equipment, and experienced personnel. We developed and demonstrated a platform that can perform these steps automatically on a single instrument. This can enable molecular diagnostics in the places and situations where it was not possible before. Graphical abstract

Background: The clinical signs of active trachoma are often present in the absence of ocular Chlamydia trachomatis infection, particularly following mass drug administration. Treatment decisions following impact surveys and in post-control surveillance for communities are currently based on the prevalence of clinical signs, which may result in further unnecessary distribution of mass antibiotic treatment and the increased spread of macrolide resistance alleles in ‘off-target’ bacterial species. We therefore developed a simple, fast, low cost diagnostic assay (DjinniChip) for diagnosis of ocular C. trachomatis for use by trachoma control programmes. Methods: The study was conducted in the UK, Germany and Tanzania. For clinical testing in Tanzania, specimens from a sample of 350 children between the ages of 7 to 15 years, which were part of a longitudinal cohort that began in February 2012 were selected. Two ocular swabs were taken from the right eye. The second swab was collected dry, kept cool in the field and archived at – 80 °C before sample lysis for DjinniChip detection and parallel nucleic acid purification and detection/quantification by qPCR assay. Results: DjinniChip was able to reliably detect > 10 copies of C. trachomatis per test and correctly identified 7/10 Quality Control for Molecular Diagnostics C. trachomatis panel samples, failing to detect 3 positive samples with genome equivalent amounts ≤ 10 copies. DjinniChip performed well across a range of typical trachoma field conditions and when used by lay personnel using a series of mock samples. In the laboratory in Tanzania, using clinical samples the sensitivity and specificity of DjinniChip for C. trachomatis was 66% (95% CI 51–78) and 94.8 (95% CI 91–97%) with an overall accuracy of 90.1 (95% CI 86.4–93). Conclusions: DjinniChip performance is extremely promising, particularly its ability to detect low concentrations of C. trachomatis and its usability in field conditions. The DjinniChip requires further development to reduce inhibition and advance toward a closed system. DjinniChip results did not vary between local laboratory results and typical trachoma field settings, illustrating its potential for use in low-resource areas to prevent unnecessary rounds of MDA and to monitor for C. trachomatis recrudescence.

Respiratory viruses can cause epidemics or pandemics, which are worldwide outbreaks of disease. The severity of these events varies depending on the virus, its characteristics, along with environmental factors. The frequency of epidemics and pandemics caused by respiratory viruses is difficult to predict, but the potential severity of such events underlines the importance of continued monitoring, research, and preparation for emerging infectious diseases. To help improve pandemic preparedness, we created a fully integrated duplex reverse transcription loop-mediated isothermal amplification (RT-LAMP) device targeting two respiratory viruses, influenza A/X-31 virus and bovine coronavirus, as a replacement for SARS-CoV-2. This device can be adapted to any other respiratory virus. In this study, we showed and evaluated a prototype of a microfluidic system, and showed that duplex RT-LAMP can detect and distinguish between the two viruses, with LoDs of 2,000 copies/ml for bovine coronavirus and 200 copies/ml for influenza A/X-31 virus. Graphical abstract

We developed an integrated version of the homogeneous SPARCL™ (Spatial Proximity Analyte Reagent Capture Luminescence) immunoassay for rapid measurement of biomarkers on a chip. Our development is based on a simple microfluidic design with on-chip preserved dry reagents. The assay requires no washing steps and can be performed in a “mix-and-read” format. A syringe pump and a luminometer supported the detection. Only one manual pipetting step is necessary to load the sample onto the chip, and the entire incubation and measurement can be accomplished in approximately 35 min. We have demonstrated the application of the SPARCL™ on a chip to the quantitative detection of the tissue inhibitor of metalloproteinases 1 (TIMP-1) in spiked mock samples and a limited number of gingival crevicular fluid specimens. The integrated SPARCL™ assay could detect as little as 49.3 pg ml⁻¹ (1.76 pM) TIMP1. To our knowledge, this is the first demonstration of the fully integrated homogeneous SPARCL™ immunoassay in a lab-on-a-chip. Further, we discuss the optimization of the chip and the assay in order to improve its analytical performance.

We assessed the viability of self-sampled gargle water direct RT-LAMP (LAMP) for detecting SARS-CoV-2 infections by estimating its sensitivity with respect to the gold standard indirect RT-PCR of paired oro-nasopharyngeal swab samples. We also assessed the impact of symptom onset to test time (STT)—i.e., symptom days at sampling, on LAMP. In addition, we appraised the viability of gargle water self-sampling versus oro-nasopharyngeal swab sampling, by comparing paired indirect RT-PCR results. 202 oro-nasopharyngeal swab and paired self-sampled gargle water samples were collected from hospital patients with COVID-19 associated symptoms. LAMP, indirect and direct RT-PCR were performed on all gargle water samples, and indirect RT-PCR was performed on all oro-nasopharyngeal samples. LAMP presented a sensitivity of 80.8% (95% CI: 70.8–90.8%) for sample pairs with sub-25 Ct oro-nasopharyngeal indirect RT-PCR results, and 77.6% (66.2–89.1%) sensitivity for sub-30 Ct samples with STT $\le$ 7 days. STT, independently of Ct value, correlated negatively with LAMP performance. 80.7% agreement was observed between gargle water and oro-nasopharyngeal indirect RT-PCR results. In conclusion, LAMP presents an acceptable sensitivity for low Ct and low STT samples. Gargle water may be considered as a viable sampling method, and LAMP as a screening method, especially for symptomatic persons with low STT values.