Pittsburgh researchers have developed a nanomaterial-based biosensor that can detect the presence of COVID-19 antibodies in 10 to 12 seconds.
A big advantage of the new sensor is that it only requires a very small amount of blood—around 5 microliters—to work. It can also detect levels of antibodies as low as 0.15 nanograms per milliliter. Another advantage is that it’s a small handheld device that can be linked up with a smartphone to provide a quick and easy readout.
Most of the current focus of COVID-19 tests is on developing those that can give an accurate and (ideally) fast readout to check if someone if currently infected with SARS-CoV-2, such as RT-PCR, RT-LAMP and antigen tests. Antibody tests are not a very accurate predictor of current infection, as it can take the body a while to begin producing them in detectable amounts.
However, antibody tests are useful for finding out whether someone has recently been infected with the virus and also for estimating if they are immune to infection or not. Research has also shown that a low antibody count in hospitalized patients can lead to poorer outcomes making it important to test a patents levels to help provide the best treatment.
Additionally, as the degree and duration of immunity that an infection with SARS-CoV-2 confers is not completely certain, more information is needed to improve the knowledge of clinicians and researchers and to help provide better advice on infection prevention and pandemic control.
As well as being able to quickly detect if someone has previously been infected with the virus, the team plans to use the sensor to help assess whether patients are responding as expected to the new vaccines that are currently being rolled out.
“Because our technique can quantify the immune response to vaccination, it is very relevant in the current environment,” emphasized lead researcher Rahul Panat, an associate professor of mechanical engineering at Carnegie Mellon University.
The device consists of tiny, gold 3D electrodes that are coated with reduced-graphene-oxide containing immobilized COVID-19 antigens – the S1 spike protein and its receptor binding domain. These are integrated into a microfluidic device.
“We utilized the latest advances in materials and manufacturing such as nanoparticle 3D printing,” explained Panat.
If there are antibodies present in the blood being tested then they selectively bind to these antigens. The device senses this as the electrical circuit changes after antibodies become bound to the electrodes. The sensor does not just detect presence of the antibodies, but can also measure amounts depending on how many of the antigens on the electrodes are bound. It can also be reset and reused as required.
“This biosensing platform will allow rapid detection and early isolation of infection, saving lives,” write the researchers in the journal Advanced Materials.
“The test platform is generic and can potentially be used to detect biomarkers for other pathogens such as Zika virus, Ebola virus, and HIV.”