An inkjet printing compatible platform for sensitive detection of dengue virus via gel based LAMP

In these current times of the COVID-19 pandemic, the need for a widely available diagnostic platform for diagnosis of viral infections cannot be overstated. Such a platform that can be easily manufactured on a large scale would be beneficial both for making clinical decisions as well as provide new tools to epidemiologists broadly screening the population during epidemic threats. Fraunhofer USA CMI has focused on manufacturability of point-of-care (POC) diagnostics as a strategic point of development that can reduce costs and close the gap between research efforts and getting devices to the market. Here we report an inkjet printed platform that has the potential to increase the sensitivity of the molecular assay, be compatible with mass manufacturing methods and allow for reagent storage on-chip. Isothermal methods such as loop-mediated isothermal amplification (LAMP) have been used for rapid disease diagnosis in low resource settings due to their increased sensitivity and lack of thermal cycling. Fluorescent based LAMP readout techniques like QUASR also lend themselves to easy deployment in field settings via smartphones. However, rather than taking the standard approach, we developed a hydrogel based LAMP (gel-RTLAMP) assay by incorporating an engineered hydrogel, highly methacrylated gelatin (GM10). In this study we show that this hydrogel is compatible with both the LAMP reaction and piezoelectric inkjet printing. Furthermore, via limit of detection studies we also show that this gel-RTLAMP assay is 100 fold more sensitive than a standard RT-LAMP assay and results in clinically relevant detection of DENV RNA in analytical samples (10 copies per reaction). Unfortunately we could not characterize the final inkjet printed platform due to time limitations and other issues, but instead we report a proof-of-principle study to show that this gel-RTLAMP assay can be adapted in a microarray format via inkjet printing and has the potential for rapid multiplexing and digitization of the assay