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Paper-based Electrochemical Sensor Detects COVID-19 in Five Minutes

A large-scale diagnosis of SARS-CoV-2 is paramount to downregulating its spread and mitigating the current outbreak.

Testing of the coronavirus disease 2019 (COVID-19) is an important strategy for tracking and containing the pandemic we find ourselves in. A recent study has created a novel test using an ultrasensitive paper-based electrochemical sensor that can rapidly detect the presence of the virus in 5 minutes or less.

Currently, there are two categories of tests on the market for COVID-19. The first category is an FDA-approved diagnostic test that employs a reverse transcriptase real-time polymerase chain reaction (RT-PCR), coupled with nucleic acid hybridization strategies to identify viral RNA. The second category mainly focuses on the detection of antibodies, which could involve a delay of up to a few weeks after an exposure to a virus.

The team behind the study created a graphene-based electrochemical biosensor with an electrical read-out setup which discerns the presence of COVID-19 genetic material. The biosensor contains two components, including a platform to measure an electrical readout and probes to detect viral RNA. Key advantages to this strategy are its sensitivity, rapid detection and low cost of production.

The investigators developed probes which targeted two regions of nucleocapsid phosphoprotein (N-gene), which helps to bolster the reliability if one of the regions undergoes gene mutation. Filtered paper is coated with a layer of graphene of viral RNA and a gold electrode with a predefined design is placed on top of the graphene as a contact for the electrical readout.

The performance of the sensor was tested by using COVID-19 positive and negative samples. In less than 5 minutes, the sensor was able to show a significant increase in the voltage of positive samples in comparison with the negative ones and confirmed the presence of viral genetic material. The sensor differentiated viral RNA loads, which is an important quantitative indicator of the progress of an infection, which has been a challenge in existing diagnostic methods.

"Currently, we are experiencing a once-in-a-century life-changing event," Maha Alafeef, co-developer of the test said. "We are responding to this global need from a holistic approach by developing multidisciplinary tools for early detection and diagnosis and treatment for SARS-CoV-2."