Researchers have developed a new method for testing viruses -including Covid-19 – using magnetic nanoparticles that assess samples from clinical and wastewater sources.
The team at KAUST (King Abdullah University of Science and Technology) said that its centrifuge-free approach is safe, fast, cheap and compatible with magnetic bead-based automated systems that are already used to process hundreds of samples.
COVID-19 is diagnosed by extracting SARS-CoV-2 viral RNA from clinical samples such as nasopharyngeal swabs, and detecting the virus using real-time reverse transcription polymerase chain reaction assays.
Due to the scale of the pandemic, shortages could occur in essential supplies for virus testing such as commercial reagents and laboratories that satisfy biosafety requirements. Conventional chemical supplies are also expensive and less accessible to low-income countries and remote healthcare facilities.
“Our silica magnetic nanoparticle-based workflow can be assembled from scratch by any researcher,” said lead author Gerardo Ramos-Mandujano. “It rivals commercial viral-RNA extraction kits while lowering the risk of handling potentially infectious samples.”
The virus has been detected in wastewater before community outbreaks, so monitoring its presence in sewage is becoming an important public health measure. Due to the risk of handling infectious samples, this requires an approach that is safe and easy to perform whilst using cheap readily-available chemicals.
To address these challenges, Ramos-Mandujano and Mo Li, assistant professor of Bioscience at KAUST, said they developed an open-source protocol for detecting RNA in clinical and environmental samples using magnetic nanoparticles which isolate nucleic acids without expensive reagents.
The technique is said to work in TRIzol, a common reagent that completely inactivates viruses, allowing clinicians to safely handle infectious samples. At 0.3 US cents per RNA extraction, the protocol is cheaper than commercial virus testing kits and produces high-quality RNA, the team said.
According to the researchers, their method also works efficiently on other human pathogenic viruses including influenza A and B and respiratory syncytial virus. When tested on wastewater samples, the researchers said they were able to recover 88 per cent of the input synthetic SARS-CoV-2 RNA.
Li said the team hopes to move the method from the lab to real-world testing sites so that it can improve capacity and decrease the cost of COVID-19 testing. The researchers believe the technique could become a useful tool for widespread community testing of different viral threats and wastewater monitoring during future pandemics, and could also be used by liquid-handling robots to extract RNA from a large number of samples.